Conformational Control of [2]Rotaxane by Hydrogen Bond.

A series of [2]rotaxanes with various functional groups in the axle component was synthesized by the oxidative dimerization of alkynes, which is mediated by a macrocyclic phenanthroline-Cu complex. The rotaxanes were fully characterized by spectroscopic methods, and the structure of a rotaxane was determined by X-ray crystallographic analysis. The interaction between the ring component and the axle component was studied in detail to understand the conformation of the rotaxanes. The presence of the hydrogen bond between the phenanthroline moiety in the macrocyclic component and the acidic proton in the axle component influenced the conformation of rotaxane.

Introduction

[2]Rotaxane is an important class of interlocked compounds, and extensive studies related to the synthesis, structure, and dynamic behavior have been reported.[1] Following the seminal study of Dietrich–Buchecker and Sauvage, who reported the synthesis of [2]catenates from macrocyclic phenanthrolines by the metal-template method,[2] Gibson and co-workers reported the synthesis of [2]rotaxane based on a similar strategy.[3] These synthetic approaches were extensively applied to the synthesis of various interlocked compounds.[4]

Recent development of the synthetic methods related to interlocked compounds includes the use of a macrocyclic metal complex as a promotor for the bond-forming reaction. The metal-mediated reaction proceeded inside the macrocyclic metal complex so that the interlocked compounds could be synthesized efficiently.[5] Leigh and co-workers reported the first example of this approach, who employed a macrocyclic pyridine–Cu complex.[6] Assuming that the Cu complex could mediate coupling reactions such as the oxidative dimerization of alkynes (Glaser coupling), we reported the synthesis of [2]rotaxanes from macrocyclic phenanthroline–Cu complex and alkynes with bulky substituents (Scheme ).[7] Interlocked compounds with polyyne structures have been synthesized by this method, and the properties of these compounds have been studied by several research groups.[8]

Scheme 1

Synthesis of [2]Rotaxane by Glaser Coupling[7a]

We have been interested in the conformation of [2]rotaxane with a macrocyclic phenanthroline ring. The phenanthroline moiety of the ring component would interact with the acidic hydrogen atom located in the axle component and the conformation of the [2]rotaxane could be affected, especially when the size of the ring component is small.[9] In this paper, we report the synthesis of small [2]rotaxanes with functionalized axle components (Scheme ). The interaction between the ring and axle components was studied to understand the conformation of [2]rotaxanes.

Scheme 2

Synthesis of Small [2]Rotaxanes with a Functionalized Axle Component

Results and Discussion

Synthesis of the Precursors for [2]Rotaxane

A macrocyclic phenanthroline–Cu complex (2) was synthesized by the reaction of 1(8f) with CuI (Scheme ). The reaction proceeded smoothly, and 2 was isolated in 61% yield.

Scheme 3

Synthesis of Macrocyclic Cu(I)–Phenanthroline Complex 2

As the precursor for the axle component, we designed a series of terminal alkynes with the tris(biphenyl)methyl group. The syntheses of the alkynes 3a–i are summarized in Schemes and 5.

Scheme 4

Synthesis of Precursors 3a–d

Scheme 5

Synthesis of Precursors 3e–i

Tris([1,1′-biphenyl]-4-yl)methanol reacted with aniline hydrochloride under acidic conditions, and the substituted aniline 5(10) was isolated in 64% yield (Scheme ). Aniline 5 was converted to aryl iodide 6 by the Sandmeyer reaction.[11] Compound 6 was further converted to alkynes with various functional groups. For example, the Sonogashira reaction of 6 with (trimethylsilyl)acetylene and the removal of the trimethylsilyl (TMS) group gave 3a in 83% yield. Similarly, the reaction of 6 with 7(12) gave alkyne 3b in comparable yield. Iodide 6 was converted to boronic acid 8 in 66% yield. The introduction of the benzyl group was achieved by the Suzuki–Miyaura reaction of 8 with 4-(trimethylsilylethynyl)benzyl bromide 9.[13] The deprotection of 10 under basic conditions gave 3c in 85% yield. An N-methylaniline derivative 11 was synthesized by the reaction of tris([1,1′-biphenyl]-4-yl)methanol and N-methylaniline hydrochloride in 21% yield. Compound 11 reacted with iodide 12(14) to give 13 in 76% yield,[15] and further removal of the TMS group gave 3d in 63% yield.

Secondary amine 3f was prepared by the Pd-catalyzed arylation of 5 and the removal of the TMS group (Scheme ). Amide 3h was synthesized by the condensation of 5 with acid 15.[16] The reduction of 3h gave amine 3g in a high yield. Fluorenylmethoxycarbonyl (Fmoc)-protected compound 3e was synthesized by treating 3g with FmocCl. Triazole derivative 3i was prepared from 6 in three steps.[6]

Synthesis of [2]Rotaxanes

With the axle precursors in hand, we studied the synthesis of rotaxanes by the reaction of 2 with 3a–i. The results are summarized in Table .

Table 1

Synthesis of a [2]Rotaxane 4 by Cu-Mediated Oxidative Coupling

Procedure A: K2CO3 (10 + 10 equiv), I2 (1.0 + 1.0 equiv), time (24 + 24 h); procedure B: K2CO3 (3.75 equiv), I2 (1.25 equiv), time (48 h).

KCN was employed for the removal of the Cu ion.

A mixture of phenanthroline–Cu complex 2 (1 equiv), alkyne 3a (2.5 equiv), I2 (1.0 equiv), and K2CO3 (10 equiv) in tetrahydrofuran (THF) was heated at 60 °C for 24 h. To the mixture was added I2 (1.0 equiv) and K2CO3 (10 equiv), and the resulting mixture was heated again for 24 h. After the removal of the Cu ion by ammonia, product 4a was isolated in 86% yield (entry 1, procedure A). Alkynes 3b and 3c were reacted with 2 under the same conditions, and [2]rotaxanes were isolated in 49% (4b) and 39% (4c) yields, respectively (entries 2 and 3). The yield of rotaxane decreased when 3d was employed as the starting material (28%, entry 4). Rotaxane 4e was isolated in 47% yield under modified conditions using smaller amounts of K2CO3 (3.75 equiv) and I2 (1.25 equiv, entry 5, procedure B): to prevent the cleavage of the Fmoc group, KCN was used to remove the Cu ion. The synthesis of 4f was examined under two reaction conditions, and the yield was better (60%) when procedure B was employed (entries 6 and 7). The reaction of benzylamine derivative 3g gave the corresponding rotaxane 4g in very low yield regardless of the procedures (entries 8 and 9). We assumed that the diarylamino group induced the removal of the copper ion from the phenanthroline moiety and suppressed the formation of rotaxane. Compound 4g was synthesized in a better yield by the removal of the Fmoc group from 4e (Scheme ). Rotaxanes 4h and 4i were synthesized in 46% and 48% yields, respectively, by procedure A (entries 10 and 11).

Scheme 6

Synthesis of [2]Rotaxane 4g by Deprotection of 4e

The structure of 4a was elucidated by X-ray crystallographic analysis, and the results are summarized in Figure . The molecular structure of 4a provided insights into the conformation of the rotaxanes. In the molecular structure obtained by the recrystallization of 4a from hexane–toluene, short contacts between the Csp carbon atoms and the hydrogen atoms bound to the aromatic ring were observed (Figure a).[8f] We also succeeded in determining the molecular structure of 4a from another sample, which was obtained by the recrystallization of 4a from methyl tert-butyl ether (MTBE)–chloroform (Figure b). In the structure, the C–H···N interaction between chloroform and the phenanthroline moiety, in addition to the short contact between the Csp carbon atom and the hydrogen atom, was detected (Figure b). A similar interaction has been reported in the literature.[17]

Figure 1

Molecular structure of [2]rotaxane 4a with thermal ellipsoids at 50% probability. Most hydrogen atoms are omitted for clarity, and noncovalent interactions are shown by red dotted lines. (a) Sample obtained by recrystallization from hexane–toluene. Co-crystallized solvent molecules (toluene and hexane) are omitted for clarity. Only the position with higher occupancy of the disordered methylene groups is shown. d(CH/Csp): (a) 2.80; (b) 2.79; (c) 2.79 Å. (b) Sample obtained by recrystallization from MTBE–chloroform. Only the position with higher occupancy of the disordered methylene and phenyl groups are shown. d(CH/N and CH/Csp): (d) 2.32; (e) 2.50; (f) 2.70 Å.

Comparison of the 1H NMR Spectra of [2]Rotaxanes

Further analysis of the structure and conformation of [2]rotaxanes was done by 1H NMR spectroscopy. In the spectra of [2]rotaxanes we studied, sharp signals were detected in most compounds and the localization of the ring component to a specific position was not observed at rt.[18,19] Based on these results, we assume that the movement of the ring component along the axle component is fast, and the observed chemical shifts are the average of the conformers. Partial 1H NMR spectra of ring component 1 and [2]rotaxanes (4a–i) are shown in Figure . We assigned the signals[20] that correspond to Hd, He, and Hf of the macrocyclic components, and the chemical shifts were compared (Table ). Based on the observed chemical shifts, rotaxanes were classified into two groups. In the compounds classified into group A (4a–e), the chemical shifts of Hd, He, and Hf appeared at 8.3–8.5, 7.1–7.2, and 7.0–7.1 ppm, respectively. It is noteworthy that the difference in the chemical shifts is small, regardless of the structure of the axle moiety. The chemical shifts of Hd and He in the phenanthroline moiety are similar to those of macrocyclic phenanthroline 1, while the chemical shift of Hf, which is bound to the resorcinol framework, shifted downfield (0.4–0.5 ppm) compared to the corresponding signal of 1. Because a larger difference of the chemical shift in the resorcinol moiety was induced by the formation of the [2]rotaxane, we assume that the “distance”[21] between the resorcinol moiety and the axle component is short: the axle component is not located in the proximity of the phenanthroline moiety.

Figure 2

1H NMR spectra of [2]rotaxanes 4a–i (500 MHz, CDCl3, 295 K).

Table 2

Comparison of the Chemical Shifts (ppm) of [2]Rotaxanes 4a–i and the Ring Component 1a

ΔHd–f = Hd–f(4) – Hd–f(1).

In contrast, the chemical shifts (Hd, He, and Hf) of the compounds classified into group B (4f–i) were significantly different from those of 4a. The chemical shifts of Hd and He in compounds that belong to group B shifted upfield compared to the corresponding chemical shifts of the compounds that belong to group A. For example, the chemical shift of Hd in 4a appeared at 8.38 ppm, while the corresponding signal in 4f appeared at 7.61 ppm.

Furthermore, the difference in the chemical shifts strongly depends on the structure of the axle moiety, implying that the axle moiety is located in the proximity of the phenanthroline moiety. Next, we compared the chemical shifts of rotaxanes (4) with those of the corresponding axle components (17, Table ). The difference between the chemical shifts of the methylene group (Hy) of 4c and 17c was small (ΔHy = −0.19 ppm): in rotaxane 4c, the signal appeared at 3.77 ppm, while the corresponding signal appeared at 3.96 ppm in 17c. A similar trend was observed when we compared the chemical shift of the methyl group of 4d with that of 17d. The difference between the chemical shifts of the methyl group was small (ΔHy = −0.16 ppm). Rotaxanes 4c and 4d belong to group A. When similar analyses were conducted with rotaxanes that belongs to group B, the difference in the chemical shifts was significantly large. The chemical shift (7.68 ppm) of the proton bound to the nitrogen atom in rotaxane (4f), for example, shifted upfield (5.87 ppm) in the axle component (17f): the difference in the chemical shifts was large (ΔHy = 1.81 ppm). Similar results were obtained when we compared the chemical shifts of rotaxanes 4g–i with diynes 17g–i. The signal assigned to Hy in 4g–i shifted upfield (1.03–1.67 ppm) in 17g–i.

Table 3

Comparison of the Chemical Shifts (ppm) of [2]Rotaxanes 4c,d,f–i with the Axle Components 17c,d,f–ia

ΔHy = Hy(4) – Hy(17).

The results summarized in Tables and 3 could be explained by assuming the presence (or absence) of the hydrogen bond between the axle component and the ring component of rotaxane. In 4c, which belong to group A, no strong interaction between the axle component and the ring component would be present, and the axle component would be located in the proximity of the resorcinol moiety to minimize the steric interaction between the bulky phenanthroline moiety and the axle component (Figure ). Consequently, the chemical shifts of Hd, He, and Hy are less affected by the presence of the axle component, while the signal of Hf shift downfield. The situation would change significantly in the rotaxanes that belong to group B.

Figure 3

Supposed major conformation of 4c and 4f in CDCl3.

In 4f, for example, the presence of the hydrogen bond between the axle component and the ring component would affect the conformation of rotaxane (Figure ). The axle component would be located in the proximity of the phenanthroline moiety. Consequently, the chemical shifts of Hd and He would be significantly affected by the presence of the axle component. The chemical shift of Hy would also be strongly affected by the presence of the macrocycle because Hy would form a hydrogen bond with the phenanthroline moiety. The formation of the hydrogen bond between the acidic triazole proton and the amine moiety in [2]rotaxane has been postulated by several research groups.[22,23]

If the conformation of rotaxane was influenced by the presence of the hydrogen bond, a notable solvent effect on the chemical shifts of rotaxanes would be observed. In a highly polar solvent, the hydrogen bond between the axle component and the ring component would be cleaved, and this would affect the conformation as well as the chemical shifts of rotaxanes. To confirm the presence of the intramolecular hydrogen bond, we selected 4c, in which the intramolecular hydrogen bond would not be present, and 4f, in which the hydrogen bond between the phenanthroline moiety and the amino group would be present. We observed the 1H NMR spectra of 4c and 4f in two solvents (DMSO-d6 and CDCl3), and the results are shown in Figure . The chemical shifts of rotaxanes 4c and 4f and ring component 1 are summarized in Table . When we observed the 1H NMR spectra of 4c and 4f in DMSO-d6, the difference in the chemical shifts of Hd, He, and Hf was small (less than 0.2 ppm), implying that 4c and 4f would adopt a similar conformation in DMSO-d6 (Table ). Meanwhile, the 1H NMR spectra of 4c and 4f were different in CDCl3. In the NMR spectrum of 4c, the signal of Hf shifted downfield (0.44 ppm) compared to the corresponding signal of macrocyclic phenanthroline 1, and the difference in other signals (Hd and He) was negligible.[24]

Figure 4

Partial 1H NMR spectra of [2]rotaxanes 4c and 4f (500 MHz, 295 K); (a) in DMSO-d6, (b) in CDCl3.

Table 4

Comparison of Chemical Shifts (ppm) of [2]Rotaxanes 4c,f and Ring Component 1a

ΔHd–f = Hd–f(4) – Hd–f(1).

The result implies that the axle component of 4c is located in the proximity of the resorcinol moiety (Figure ). In contrast, the chemical shifts of Hd and He shifted upfield (0.76 and 0.50 ppm, respectively) in 4f compared to the corresponding signals of 1, while the difference in the chemical shifts of Hf was small (0.04 ppm). The result could be explained by postulating the presence of the intramolecular hydrogen bond between the axle component and the ring component of 4f (Figure ). The axle component of 4f would be located in the proximity of the phenanthroline moiety, and the chemical shifts of Hd and He would be strongly affected.

The presence of the intramolecular hydrogen bond was also supported by comparing the 1H NMR chemical shifts of the axle moiety of rotaxanes and related compounds in different solvents (Table ). The difference in the chemical shifts of the methylene group of 4c and that of 17c in DMSO-d6 was small (−0.20 ppm). Similar results were observed when the chemical shifts of the NH group of 4f and that of 17f in DMSO-d6 were compared or the chemical shifts of the methylene group of 4c and that of 17c in CDCl3 were compared. In contrast, a large difference (1.81 ppm) was observed when the chemical shifts of the NH group of 4f and that of 17f in CDCl3 were compared. The results could be reasonably interpreted by postulating that the intramolecular hydrogen bond is present in a solution of 4f in CDCl3.[25]

Table 5

Comparison of the Chemical Shifts (ppm) of [2]Rotaxanes 4c,f and the Axle Components 17c,fa

ΔHy = Hy(4) – Hy(17).

Variable-Temperature 1H NMR Experiments

We assumed that the conformation of [2]rotaxanes of group B adopted a structure with a low symmetry (Figure b). The observed NMR spectra at 295 K, however, do not directly correspond to the assumed conformation; the signals of the two dumbbell moieties, for example, were equivalent. The observed NMR spectra of [2]rotaxanes of group B could be explained in terms of the fast shuttling of the ring component at 295 K (Figure ).[22,26]

Figure 5

Expected shuttling behavior of group B rotaxanes.

Expecting that the rate of the shuttling would decrease at low temperatures and that the signals that reflect the less symmetric structure of [2]rotaxane would appear, we conducted the variable-temperature 1H NMR experiments of 4c, 4f, and 4h in CD2Cl2. When the 1H NMR spectrum of 4c, a negative control, was observed at low temperatures, only the broadening of the signals was observed, and the difference in the chemical shifts was small (Figure S1). Similar results were obtained when the 1H NMR spectrum of 4f, a rotaxane that would form a hydrogen bond, was recorded (Figure S2). In 4h, on the other hand, the chemical shift of the amide group (Hy, 11.59 ppm) at 188 K was downfield (1.6 ppm) compared to the corresponding signal at 203 K (9.95 ppm, Figure ). We assume that the signal observed at 203 K (9.95 ppm) split into two signals at a low temperature (188 K). One signal that appeared at 11.59 ppm would correspond to the amide proton that interacted with the phenanthroline moiety by the hydrogen bond, and the other signal was not detected because the signal overlapped with other signals.[27] Based on the observed data, the activation energy for the shuttling process of 4h was assumed to be 8 kcal/mol.[28,29]

Figure 6

Partial VT 1H NMR spectra of 4h (500 MHz, CD2Cl2).

We anticipated that the N–H···N interaction would be stronger in a less polar solvent and observed the 1H NMR spectra of 4f in toluene-d8 (Figure c, bottom). Notably, two NH signals were observed at 4.86 and 10.70 ppm at 193 K. We confirmed that these signals correspond to the amino group by observing the 1H NMR spectra of the deuterated compound 4f- (78 atom % D of the N–D bond, Figure b, middle). Because the signal of the amino group of 17f (the axle component of 4f) was observed at 4.83 ppm in toluene-d8 at 193 K (Figure a, top), the signal of 4f, which appeared at 4.86 ppm, could be assigned to the free amino group, while the signal observed at 10.70 ppm would correspond to the amino group that interacted with the phenanthroline moiety. The amino groups in 4f appeared as two non-equivalent signals at 193 K due to the decrease in the rate of the shuttling.[8h,30]

Figure 7

Partial 1H NMR spectra of 4f (bottom, c), 4f- (middle, b), and 17f (top, a) at 193 K (400 MHz, toluene-d8).

Conclusions

In summary, we synthesized [2]rotaxanes with various functional groups and studied the conformation of the compounds. The comparison of 1H NMR spectra of [2]rotaxanes and related components in CDCl3 showed that the spectra of rotaxanes were significantly affected by the structure of the axle component. The result could be explained by postulating the presence of the intramolecular hydrogen bond between the phenanthroline moiety and the acidic hydrogen atom in the axle component. The observation of some non-equivalent 1H NMR signals at low temperatures supports the idea that the shuttling of the ring component occurs in some rotaxanes that form hydrogen bonds. The study would contribute to the understanding of the conformation of the interlocked compounds.

Experimental Section

General Methods

Reagents were commercially available and were used without further purification. An oil bath or a bead bath was used as the heat source, and the external temperature was reported. NMR spectra were recorded on a JEOL 400 or 500 MHz spectrometer or a Bruker 400 MHz NMR spectrometer. Chemical shifts were reported in delta units (δ) relative to chloroform (7.24 ppm for 1H NMR and 77.0 ppm for 13C NMR) or dimethyl sulfoxide (DMSO) (2.50 ppm for 1H NMR and 39.5 ppm for 13C NMR). Multiplicity is indicated by s (singlet), d (doublet), t (triplet), q (quartet), quint (quintet), m (multiplet), or br (broad). Coupling constants, J, are reported in Hertz. IR spectra were recorded on a Fourier transform infrared spectrometer using a diamond ATR module. A YMC-GPC T30000 (21.2 mm ID  ×  600 mm L) column was used for GPC separation using CHCl3 as the eluent. Thin layer chromatography was performed on Merck silica gel 60F-254 plates. Column chromatography was performed using Kanto Chemical silica gel 60N (spherical, neutral 40–50 μm). High-resolution mass spectra (HRMS) were obtained by using a time-of-flight (TOF) mass analyzer.

Macrocyclic Cu(I)–Phenanthroline Complex (2)

To a solution of 1(8f) (408 mg, 0.70 mmol) in CH2Cl2 (35 mL) was added a solution of CuI (133 mg, 0.70 mmol, 1 equiv) in CH3CN (14 mL), and the mixture was stirred at rt for 2 h. The solvent was removed in vacuo, and the residue was recrystallized from hexane–CH2Cl2 to yield 2 (328 mg, 0.42 mmol, 61%) as an orange powder: mp 171.1–172.2 °C; 1H NMR (400 MHz, CDCl3): δ 8.44 (d, J = 7.6 Hz, 2H), 8.02 (br, 8H), 7.13 (m, 5H), 7.10 (t, J = 8.6 Hz, 1H), 6.59 (s, 2H), 6.47 (d, J = 8.4 Hz, 2H), 4,29 (t, J = 6.2 Hz, 4H), 4.03 (s, 4H), 2.06 (br, 4H), 1.93 (br, 4H); 13C{1H} NMR (100 MHz, DMSO-d6, 423 K): δ 161.0, 160.9, 160.7, 144.6, 138.1, 130.6, 130.5, 130.3, 126.9, 126.7, 116.3, 108.1, 103.2, 79.6, 68.8, 26.3, 26.1 (one signal is missing); IR (ATR): 1603, 1582, 1487 cm–1; Anal. Calcd for C38H34CuIN2O4·1.6 (CH2Cl2): C, 52.32; H, 4.12; N, 3.08. Found: C, 52.38; H, 3.73; N, 3.01.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]iodobenzene (6)

A mixture of 4-[tris([1,1′-biphenyl]-4-yl)methyl]aniline 5(10) (2.82 g, 5.0 mmol), NaNO2 (1.73 g, 25 mmol, 5 equiv), CH2I2 (2.68 g, 10 mmol, 2 equiv), CH2Cl2 (50 mL), and H2O (25 mL) was stirred at rt for 5 min under Ar. After the addition of acetic acid (6.01 g, 100 mmol, 20 equiv), the mixture was refluxed for 3 h, cooled to rt, and extracted with CH2Cl2 (3 × 30 mL). The combined organic layer was washed with water, dried over MgSO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 5/1) to yield 6 (2.26 g, 3.4 mmol, 68%) as a colorless solid; mp 215.7–218.4 °C; 1H NMR (500 MHz, CDCl3): δ 7.61 (d, J = 9.2 Hz, 2H), 7.59 (d, J = 8.0 Hz, 6H), 7.51 (d, J = 8.0 Hz, 6H), 7.41 (t, J = 8.0 Hz, 6H), 7.30–7.33 (m, 9H), 7.08 (d, J = 7.5 Hz, 2H); 13C{1H} NMR (100 MHz, CDCl3): δ 146.6, 145.2, 140.4, 138.8, 136.7, 133.2, 131.3, 128.8, 127.3, 127.0, 126.3, 91.9, 64.1; IR (ATR): 1484 cm–1; HRMS (FAB): calcd for C43H31I ([M]+), 674.1470; found, 674.1468.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]ethynylbenzene (3a)

A mixture of 6 (421 mg, 0.62 mmol), Pd[(PPh3)2]Cl2 (13.1 mg, 0.019 mmol, 3.0 mol %), and CuI (7.1 mg, 0.037 mmol, 6.0 mol %) in dry THF (10 mL) and dry triethylamine (10 mL) was stirred at rt for 5 min under Ar. (Trimethylsilyl)acetylene (0.10 mL, 0.72 mmol, 1.2 equiv) was added in one portion, and the mixture was stirred at rt for 30 min. Saturated NH4Cl aq (10 mL) was poured into the solution, and the mixture was extracted with MTBE (3 × 30 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. To the residue were added K2CO3 (172 mg, 1.3 mmol, 2.0 equiv), CH2Cl2 (20 mL), and MeOH (10 mL), and the mixture was stirred at rt for 1 h. After the addition of water, the mixture was extracted with CH2Cl2 (3 × 25 mL). The combined organic layer was washed with water, dried over MgSO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 5/1) to yield 3a (298 mg, 0.52 mmol, 83%) as a white solid; mp 232.8–234.6 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 7.5 Hz, 6H), 7.52 (d, J = 8.6 Hz, 6H), 7.40–7.45 (m, 8H), 7.30–7.34 (m, 11H), 3.05 (s, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 147.6, 145.3, 140.4, 138.8, 131.44, 131.39, 131.0, 128.8, 127.3, 127.0, 126.3, 119.7, 83.5, 77.1, 64.3; IR (ATR): 1486 cm–1; HRMS (ESI): calcd for C45H32 ([M]+), 572.2499; found, 572.2496.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-([4-ethynylphenyl]ethynyl)benzene (3b)

A mixture of 6 (337 mg, 0.5 mmol), Pd[(PPh3)2]Cl2 (10.5 mg, 0.015 mmol, 3.0 mol %), and CuI (5.71 mg, 0.030 mmol, 6.0 mol %) in dry THF (10 mL) and dry triethylamine (10 mL) was stirred at rt for 5 min. To the mixture was added ([4-ethynylphenyl]ethynyl)trimethylsilane 7 (99.2 mg, 0.5 mmol, 1.0 equiv), and the resulting mixture was stirred for 30 min. The mixture was added to a saturated aqueous solution of NH4Cl (10 mL) and extracted with MTBE (3 × 30 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo; To the residue was added K2CO3 (138 mg, 1.0 mmol, 2.0 equiv), CH2Cl2 (20 mL), and MeOH (10 mL), and the mixture was stirred at rt for 1 h. After the addition of water, the mixture was extracted with CH2Cl2 (3 × 25 mL). The combined organic layer was washed with water, dried over MgSO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 5/1) to yield 3b (273 mg, 0.41 mmol, 81%) as a white solid; mp 238.8–240.4 °C; 1H NMR (500 MHz, CDCl3): δ 7.61 (d, J = 7.5 Hz, 6H), 7.53 (d, J = 8.6 Hz, 6H), 7.41–7.47 (m, 12H), 7.31–7.37 (m, 11H), 3.15 (s, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 147.4, 145.4, 140.4, 138.8, 132.0, 131.5, 131.4, 131.1, 130.9, 128.8, 127.3, 127.0, 126.3, 123.8, 121.8, 120.5, 91.2, 89.0, 83.3, 78.9, 64.3; IR (ATR): 1512, 1486 cm–1; HRMS (ESI): calcd for C53H36 ([M]+), 672.2812; found, 672.2803.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]phenylboronic Acid (8)

A mixture of 6 (880 mg, 1.3 mmol) in dry THF (8 mL) was cooled to −78 °C under Ar. Then, n-BuLi in hexane (1.00 mL, 1.57 M, 1.56 mmol, 1.2 equiv) and B(OMe)3 (0.35 mL, 0.33 mmol, 2.4 equiv) were added, and the mixture was stirred for 2 h. The mixture was allowed to warm to rt and stirred again for 2 h. Saturated NH4Cl aq (10 mL) was poured into the reaction mixture, and the resulting mixture was stirred for 5 min and extracted with MTBE (3 × 20 mL). The combined organic layer was washed with water, dried over MgSO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/2) to yield 8 (510 mg, 0.86 mmol, 66%) as a colorless amorphous solid; mp 231.1–232.7 °C; 1H NMR (500 MHz, DMSO-d6): δ 8.03 (s, 2H), 7.75 (d, J = 8.6 Hz, 2H), 7.66–7.69 (m, 12H), 7.45 (t, J = 8.0 Hz, 6H), 7.34–7.37 (m, 9H), 7.26 (d, J = 8.6 Hz, 2H); 13C{1H} NMR (100 MHz, DMSO-d6): δ 149.7, 147.1, 141.0, 139.2, 135.3, 133.5, 132.6, 131.1, 130.5, 129.0, 128.1, 127.6, 65.6; IR (ATR): 1485 cm–1; Anal. Calcd for C43H33BO2 (−1/6 H2O): C, 87.61; H, 5.59. Found: C, 87.68; H, 5.59.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-(4-[trimethylsilyl]ethynylbenzyl)benzene (10)

To a mixture of 8 (398 mg, 0.67 mmol), [(4-[bromomethyl]phenyl)ethynyl]trimethylsilane 9 (179 mg, 0.67 mmol, 1.0 equiv), K2CO3 (232 mg, 1.7 mmol, 2.5 equiv), acetone (5.1 mL), and water (1.7 mL) was added PdCl2 (2.01 mg, 0.011 mmol, 1.7 mol %) at rt under Ar with stirring. The mixture was heated to 50 °C for 22 h. The solvent was cooled to rt and extracted with CH2Cl2 (3 × 20 mL). The combined organic layer was dried over Na2SO4 and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 3/1) to yield 10 (224 mg, 0.31 mmol, 45%) as a white solid; mp 237.5–239.9 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 7.5 Hz, 6H), 7.51 (d, J = 8.0 Hz, 6H), 7.38–7.42 (m, 8H), 7.30–7.34 (m, 9H), 7.22 (d, J = 8.0 Hz, 2H), 7.14 (d, J = 8.0 Hz, 2H), 7.07 (d, J = 8.0 Hz, 2H), 3.94 (s, 2H), 0.23 (s, 9H); 13C{1H} NMR (100 MHz, CDCl3): δ 145.9, 144.6, 141.6, 140.5, 138.6, 138.3, 132.1, 131.5, 131.2, 128.9, 128.7, 128.0, 127.2, 126.9, 126.1, 120.9, 105.1, 93.7, 64.0, 41.4, 0.0; IR (ATR): 1618, 1508, 1484 cm–1; HRMS (FAB): calcd for C55H46Si ([M]+), 734.3369; found, 734.3368.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-(4-ethynylbenzyl)benzene (3c)

A mixture of 10 (184 mg, 0.25 mmol), KOH (21.0 mg, 0.38 mmol, 1.5 equiv), MeOH (2.4 mL), and THF (9.6 mL) was stirred at rt for 1 h. To the solution was added water, and the mixture was extracted with EtOAc (3 × 20 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 3/1) to yield 3c (140 mg, 0.21 mmol, 85%) as a white solid; mp 210.0–212.4 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 6H), 7.51 (d, J = 6.9 Hz, 6H), 7.39–7.42 (m, 8H), 7.30–7.35 (m, 9H), 7.23 (d, J = 6.9 Hz, 2H), 7.17 (d, J = 7.5 Hz, 2H), 7.08 (d, J = 8.0 Hz), 3.95 (s, 2H), 3.02 (s, 1H); 13C{1H} NMR (100 MHz, CDCl3): δ 145.8, 144.7, 141.9, 140.5, 138.6, 138.2, 132.3, 131.5, 131.3, 129.0, 128.7, 128.0, 127.2, 126.9, 126.1, 119.8, 83.6, 77.2, 76.8, 64.1, 41.3; IR (ATR): 1506, 1484 cm–1; HRMS (ESI): calcd for C52H39 ([M + H]+), 663.3046; found, 663.3035.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N-methylaniline (11)

A mixture of tris([1,1′-biphenyl]-4-yl)methanol (2.44 g, 5.0 mmol) and N-methylaniline hydrochloride (1.44 g, 10 mmol, 2 equiv) in dry toluene (10 mL) and acetic acid (10 mL) was refluxed under Ar for 3 h. The mixture was cooled to rt and extracted with CHCl3 (3 × 100 mL). Saturated NaHCO3 aq (100 mL) was added to the combined organic layer, and the mixture was stirred for 1 h. The organic layer was separated, and the water layer was extracted with CHCl3 (3 × 50 mL). The combined organic layer was dried over Na2SO4 and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/2) to yield 11 (608 mg, 1.1 mmol, 21%) as a white solid; mp 230.5–233.1 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 6H), 7.50 (d, J = 8.6 Hz, 6H), 7.40 (t, J = 8.0 Hz, 6H), 7.35 (d, J = 8.0 Hz, 6H), 7.30 (t, J = 7.5 Hz, 3H), 7.11 (d, J = 8.6 Hz, 2H), 6.58 (d, J = 8.0 Hz, 2H), 4.07 (br, 1H), 2.83 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 147.1, 146.4, 140.7, 138.3, 135.4, 132.0, 131.5, 128.7, 127.1, 126.9, 126.0, 111.5, 63.6, 30.7; IR (ATR): 1613, 1520, 1485, cm–1; HRMS (ESI): calcd for C44H36N ([M + H]+), 578.2842; found, 578.2845.

General Procedure for Amination

A mixture of arylamine (1.0 equiv), ([4-iodophenyl]ethynyl)trimethylsilane 12 (1.1 equiv), NaOt-Bu in THF (1.0 M, 1.3 equiv), tri-tert-butylphosphonium tetrafluoroborate (10 mol %), Pd2(dba)3 (5 mol %), and toluene (4.0 mL/1.0 mmol of arylamine) was refluxed under Ar for 17 h. To the solution was added water, and the mixture was extracted with CH2Cl2. The combined organic layer was washed with water, dried over MgSO4, and concentrated in vacuo. The residue was purified by column chromatography.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N,N-methyl-(4-[trimethylsilyl]ethynylphenyl)aniline (13)

Following the general procedure for amination, 11 (289 mg, 0.5 mmol), 12 (165 mg, 0.55 mmol, 1.1 equiv), NaOt-Bu in THF (1.0 M, 0.65 mL, 0.65 mmol, 1.3 equiv), tri-tert-butylphosphonium tetrafluoroborate (14.5 mg, 0.050 mmol), Pd2(dba)3 (22.9 mg, 0.025 mmol), and toluene (2.0 mL) were used. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 2/1) to yield 13 (284 mg, 0.38 mmol, 76%) as a white solid; mp 224.0–225.7 °C; 1H NMR (500 MHz, CDCl3): δ 7.60 (d, J = 7.5 Hz, 6H), 7.53 (d, J = 8.6 Hz, 6H), 7.41 (t, J = 7.5 Hz, 6H), 7.36 (d, J = 8.6 Hz, 6H),7.30–7.33 (m, 5H), 7.23 (d, J = 6.9 Hz, 2H), 7.01 (d, J = 9.2 Hz, 2H), 6.87 (d, J = 8.6 Hz, 2H), 3.31 (s, 3H), 0.21 (s, 9H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.7, 145.9, 145.8, 141.1, 140.5, 138.6, 132.9, 132.0, 131.4, 128.7, 127.2, 126.9, 126.2, 121.5, 117.5, 113.8, 105.8, 92.3, 77.2, 63.8, 40.0, 0.1; IR (ATR): 1505, 1484 cm–1; HRMS (ESI): calcd for C55H48NSi ([M]+), 750.3551; found, 750.3541.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N-(4-[trimethylsilyl]ethynylphenyl)aniline (14)

Following the general procedure for amination, 4-[tris([1,1′-biphenyl]-4-yl)methyl]aniline 5 (564 mg, 1.0 mmol), 12 (330 mg, 1.1 mmol, 1.1 equiv), NaOt-Bu in THF (1.0 M, 1.3 mL, 1.3 mmol, 1.3 equiv), tri-tert-butylphosphonium tetrafluoroborate (29.0 mg, 0.10 mmol), Pd2(dba)3 (45.8 mg, 0.050 mmol), and toluene (4.0 mL) were used. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 14 (437 mg, 0.594 mmol, 59%) as a white solid; mp 146.3–150.1 °C; 1H NMR (500 MHz, CDCl3): δ 7.60 (d, J = 7.5 Hz, 6H), 7.52 (d, J = 8.6 Hz, 6H), 7.41 (t, J = 7.5 Hz, 6H), 7.30–7.36 (m, 11H), 7.21 (d, J = 8.6 Hz, 2H), 7.02 (d, J = 8.6 Hz, 2H), 6.96 (d, J = 8.6 Hz, 2H), 5.81 (s, 1H), 0.21 (s, 9H); 13C{1H} NMR (126 MHz, CDCl3): δ 145.9, 143.3, 140.5, 140.0, 139.7, 138.6, 133.2, 132.1, 131.4, 128.7, 127.2, 126.9, 126.1, 117.5, 116.2, 114.4, 92.3, 77.2, 63.8, 0.1; IR (ATR): 1600, 1514, 1486 cm–1; HRMS (ESI): calcd for C54H46NSi ([M + H]+), 736.3394; found, 736.3409.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N,N-methyl-(4-ethynylphenyl)aniline (3d)

A mixture of 13 (298 mg 0.40 mmol), KOH (33.4 mg, 0.60 mmol, 1.5 equiv), MeOH (3.2 mL), and THF (12.8 mL) was stirred at rt for 1 h. To the solution was added water, and the mixture was extracted with EtOAc (3 × 20 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 3d (167 mg, 0.25 mmol, 63%) as a white solid; mp 217.1–219.0 °C; 1H NMR (500 MHz, CDCl3): δ 7.60 (d, J = 8.0 Hz, 6H), 7.53 (d, J = 8.0 Hz, 6H), 7.41 (t, J = 7.5 Hz, 6H), 7.30–7.37 (m, 11H), 7.25 (d, J = 5.2 Hz, 2H), 7.03 (d, J = 8.0 Hz, 2H), 6.88 (d, J = 8.0 Hz, 2H), 3.32 (s, 3H), 3.00 (s, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 148.9, 145.9, 145.7, 141.3, 140.5, 138.6, 133.1, 132.1, 131.5, 128.7, 127.2, 126.9, 126.2, 121.7, 117.3, 112.5, 84.3, 75.6, 63.9, 40.0; IR (ATR): 1598, 1505, 1485 cm–1; HRMS (ESI): calcd for C52H40N ([M + H]+), 678.3147; found, 678.3155.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N-(4-ethynylphenyl)aniline (3f)

A mixture of 14 (107 mg 0.15 mmol), KOH (12 mg, 0.22 mmol, 1.5 equiv), MeOH (1.6 mL), and THF (6.4 mL) was stirred at rt for 1 h. To the solution was added water, and the mixture was extracted with EtOAc (3 × 10 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 3f (87.0 mg, 0.073 mmol, 90%) as a white solid; mp 253.3–255.6 °C; 1H NMR (500 MHz, CDCl3): δ 7.60 (d, J = 7.5 Hz, 6H), 7.53 (d, J = 8.6 Hz, 6H), 7.42 (t, J = 7.5 Hz, 6H), 7.36 (d, J = 8.6 Hz, 6H), 7.36 (d, J = 8.6 Hz, 2H), 7.32 (t, J = 7.5 Hz, 3H), 7.23 (d, J = 8.6 Hz, 2H), 7.03 (d, J = 8.6 Hz, 2H), 6.98 (d, J = 8.6 Hz, 2H), 5.82 (s, 1H), 2.99 (s, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 145.9, 143.7, 140.5, 140.2, 139.6, 138.6, 133.4, 132.1, 131.4, 128.7, 127.2, 126.9, 126.2, 117.7, 116.2, 113.3, 84.1, 75.7, 63.8; IR (ATR): 1600, 1510, 1485 cm–1; HRMS (ESI): calcd for C51H38N ([M + H]+), 664.2999; found, 664.2996.

N-([4-Tris([1,1′-biphenyl]-4-yl)methyl]phenyl)-4-ethynylbenzamide (3h)

A mixture of 4-[tris([1,1′-biphenyl]-4-yl)methyl]benzenamine 5 (564 mg 1.0 mmol), 4-ethynylbenzoic acid 16 (146 mg, 1.0 mmol, 1.0 equiv), EDC (230 mg, 1.2 mmol, 1.2 equiv), and HOBt·H2O (184 mg, 1.20 mmol, 1.2 equiv) in anhydrous dimethylformamide (DMF) (5 mL) was stirred at rt for 18 h. To the solution was added water, and the mixture was extracted with EtOAc (3 × 20 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/2) to yield 3h (600 mg, 0.87 mmol, 87%) as a white solid; mp 238.2–240.2 °C; 1H NMR (500 MHz, CDCl3): δ 7.81 (d, J = 8.0 Hz, 2H), 7.75 (s, 1H), 7.58–7.60 (m, 8H), 7.56 (d, J = 9.2 Hz, 2H), 7.52 (d, J = 8.6 Hz, 6H), 7.41 (t, J = 7.5 Hz, 6H), 7.30–7.37 (m, 11H), 3.21 (s, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 164.9, 145.7, 143.2, 140.5, 138.7, 135.6, 134.8, 132.5, 131.8, 131.4, 128.7, 127.2, 127.0, 126.7, 126.2, 125.8, 119.4, 82.6, 79.9, 64.0; IR (ATR): 1673, 1597, 1518, 1487 cm–1; HRMS (ESI): calcd for C52H38NO ([M + H]+), 692.2948; found, 692.2954.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N-(4-ethynylbenzyl)aniline (3g)

To a solution of 3h (257 mg, 0.37 mmol) in anhydrous THF (5 mL) was added a suspension of LiAlH4 (42.3 mg, 1.1 mmol, 3.0 equiv) in THF (1.1 mL) at 0 °C under Ar with stirring. The mixture was stirred at 70 °C for 2 h. To the mixture was added aqueous NaOH (7.5%, 0.2 mL), and the mixture was stirred for 5 min at rt. The mixture was filtered over Celite, and the filter cake was rinsed with EtOAc. The combined organic layer was dried over MgSO4 and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 3g (227 mg, 0.335 mmol, 90%) as a white solid; mp 118.9–120.0 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 6H), 7.49 (d, J = 8.0 Hz, 6H), 7.45 (d, J = 8.0 Hz, 2H), 7.41 (t, J = 7.5 Hz, 6H), 7.29–7.34 (m, 11H), 7.09 (d, J = 8.6 Hz, 2H), 6.56 (d, J = 7.5 Hz, 2H), 4.31, (s, 2H), 4.08 (br, 1H) 3.04 (s, 1H); 13C{1H} NMR (100 MHz, CDCl3): δ 146.3, 145.8, 140.6, 140.4, 138.4, 135.9, 132.4, 132.0, 131.5, 128.7, 127.4, 127.1, 126.9, 126.0, 120.9, 111.9, 83.5, 77.1, 63.6, 48.2; IR (ATR): 3425, 3286, 1611, 1514, 1485 cm–1; HRMS (ESI): calcd for C52H40N ([M + H]+), 678.3155; found, 678.3152.

4-[Tris([1,1′-biphenyl]-4-yl)methyl]-N,N-(4-ethynylbenzyl)-[(9H-fluoren-9-ylmethoxy)carbonyl]aniline (3e)

A mixture of 3g (482 mg, 0.71 mmol), (9H-fluoren-9-yl)methyl carbonochloridate (221 mg, 0.85 mmol, 1.2 equiv) in dry CHCl3 (10 mL) was stirred at 80 °C under Ar for 16 h. The solution was concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 3e (583 mg, 0.65 mmol, 91%) as a white solid; mp 122.8–124.2 °C; 1H NMR (400 MHz, CDCl3, 333 K): δ 7.66 (d, J = 7.3 Hz, 2H), 7.60 (d, J = 7.8 Hz, 6H), 7.52 (d, J = 8.2 Hz, 6H), 7.41 (t, J = 7.3 Hz, 6H), 7.30–7.38 (m, 15H), 7.22 (dd, J = 7.3, 1.8 Hz, 2H), 7.17 (t, J = 7.3 Hz, 2H), 7.07 (d, J = 7.8 Hz, 2H), 6.93 (d, J = 7.8 Hz, 2H), 4.79 (s, 2H), 4.54 (d, J = 6.4 Hz, 2H), 4.11 (t, J = 6.4 Hz, 1H), 3.03 (s, J = 7.3 Hz, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 155.5, 145.5, 145.1, 143.7, 141.3, 140.4, 139.3, 138.7, 138.5, 132.2, 131.6, 131.4, 128.7, 128.5, 127.6, 127.2, 126.9, 126.9, 126.2, 124.9, 121.0, 119.8, 83.4, 77.3, 67.4, 63.9, 53.9, 47.2; IR (ATR): 1716, 1512, 1488 cm–1; HRMS (ESI): calcd for C67H50NO2 ([M + H]+), 900.3836; found, 900.3833.

1-Azido-4-[tris([1,1′-biphenyl]-4-yl)methyl]benzene (16)

A mixture of 6 (1.08 g 1.6 mmol), NaN3 (125 mg, 1.9 mmol, 1.2 equiv), l-proline (36.8 mg, 0.32 mmol, 0.2 equiv), NaOH (12.8 mg, 0.32 mmol, 0.2 equiv), and CuI (30.5 mg, 0.160 mmol, 0.1 equiv) in dry DMSO (6 mL) was stirred at 90 °C under Ar for 6 h. To the mixture was added water at rt, and the mixture was extracted with EtOAc (3 × 20 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 16 (430 mg, 0.73 mmol, 46%) as a white solid; mp 174.9–177.0 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 7.5 Hz, 6H), 7.52 (d, J = 8.6 Hz, 6H), 7.41 (t, J = 8.0 Hz, 2H), 7.30–7.34 (m, 11H), 7.08 (d, J = 8.6 Hz, 2H); 13C{1H} NMR (75 MHz, CDCl3): δ 145.5, 143.6, 140.4, 138.8, 137.8, 132.5, 131.4, 128.8, 127.3, 126.9, 126.3, 118.2, 63.9; IR (ATR): 2118, 2082, 1600, 1504, 1487 cm–1; HRMS (FAB): calcd for C43H31N3 ([M]+), 589.2518; found, 589.2508.

1-([4-Tris([1,1′-biphenyl]-4-yl)methyl]phenyl)-4-(4-ethynylphenyl)-1H-1,2,3-triazole (3i)

A mixture of 16 (177 mg, 0.30 mmol), ([4-ethynylphenyl]ethynyl)trimethylsilane (71.4 mg, 0.36 mmol, 1.15 equiv), l-sodium ascorbate (11.9 mg, 0.060 mmol, 0.2 equiv), and CuSO4·5H2O (15.0 mg, 0.060 mmol, 0.2 equiv) in dry DMF (5 mL) was stirred at rt for 2 days. Saturated NH4Cl aq (10 mL) was poured into the solution, and the mixture was extracted with EtOAc (3 × 15 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was treated with a solution of KOH (252 mg, 0.45 mmol, 1.5 equiv) in a mixture of THF (16 mL) and MeOH (4 mL), and the mixture was stirred at rt for 1 h. Water was added to the solution, and the mixture was extracted with CH2Cl2 (3 × 15 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/CH2Cl2 = 1/1) to yield 3i (184 mg, 0.26 mmol, 86%) as a white solid; mp 226.0–227.2 °C; 1H NMR (500 MHz, CDCl3): δ 8.18 (s, 1H), 7.86 (d, J = 8.6 Hz, 2H), 7.71 (d, J = 9.2 Hz, 2H), 7.60 (d, J = 8.6 Hz, 6H), 7.53–7.58 (m, 10H), 7.42 (t, J = 7.5 Hz, 6H), 7.38 (d, J = 8.6 Hz, 6H), 7.33 (t, J = 7.5 Hz, 3H), 3.13 (s, 1H); 13C{1H} NMR (126 MHz, CDCl3): δ 147.9, 147.6, 145.2, 140.3, 139.0, 134.8, 132.7, 132.4, 131.3, 130.5, 128.8, 127.4, 127.0, 126.4, 125.6, 122.0, 119.8, 117.9, 83.4, 78.1, 64.2; IR (ATR): 3285, 1516, 1486 cm–1; HRMS (FAB): calcd for C53H38N3 ([M]+), 716.3066; found, 716.3066.

General Procedure A for the Synthesis of [2]Rotaxanes

A mixture of macrocyclic phenanthroline–CuI complex 2 (1.0 equiv), alkyne (2.5 equiv), K2CO3 (10 equiv), and I2 (1.0 equiv) in dry THF (6.25 mL/0.1 mmol of 2) was stirred at 60 °C under Ar for 24 h. Then, K2CO3 (10 equiv) and I2 (1.0 equiv) were added, and the mixture was stirred again at 60 °C for 24 h. The mixture was cooled to rt, and CH2Cl2 (7.5 mL/0.1 mmol of 2), CH3CN (17.5 mL/0.1 mmol of 2), and NH3 aq (30%, 8.5 mL/0.1 mmol of 2) were added. After stirring at rt overnight, the solution was extracted with CH2Cl2, dried over Na2SO4, and concentrated in vacuo. The residue was purified by column chromatography and GPC.

General Procedure B for the Synthesis of [2]Rotaxanes

A mixture of macrocyclic phenanthroline–CuI complex 2 (1.0 equiv), alkyne (2.5 equiv), K2CO3 (3.75 equiv), and I2 (1.25 equiv) in dry THF (6.25 mL/0.1 mmol of 2) was stirred at 60 °C under Ar for 48 h. The solution was cooled to rt, and CH2Cl2 (7.5 mL/0.1 mmol of 2), CH3CN (17.5 mL/0.1 mmol of 2), and NH3 aq (30%, 8.5 mL/0.1 mmol of 2) were added. After stirring at rt overnight, the solution was extracted with CH2Cl2. The organic layer was dried over Na2SO4 and concentrated in vacuo. The residue was purified by column chromatography and GPC.

[2]Rotaxane (4a) and Diyne (17a)

Following the general procedure A, 2 (77.3 mg, 0.10 mmol), 3a (143 mg, 0.25 mmol), K2CO3 (138 + 138 mg, 1.0 + 1.0 mmol), and I2 (25.4 + 25.4 mg, 0.10 + 0.10 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/1) to yield 4a (108 mg, 0.063 mmol, 86%) as a white solid. The diyne 17a (28 mg, 0.024 mmol, 20%, based on 3a) was also isolated as a white solid. Data for 4a: mp 182.1–184.9 °C; 1H NMR (500 MHz, CDCl3): δ 8.38 (d, J = 8.6 Hz, 4H), 8.14 (d, J = 8.6 Hz, 2H), 7.96 (d, J = 8.6 Hz, 2H), 7.62 (s, 2H), 7.53 (d, J = 8.6 Hz, 12H), 7.38–7.41 (m, 28H), 7.30 (t, J = 7.5 Hz, 6H), 7.20 (d, J = 8.6 Hz, 4H), 7.15 (d, J = 8.6 Hz, 12H), 7.04 (t, J = 8.0 Hz, 1H), 7.00 (d, J = 8.6 Hz, 4H), 6.98 (t, J = 2.3 Hz, 1H), 6.42 (dd, J = 2.3, 8.6 Hz, 2H), 4.22 (t, J = 7.5 Hz, 4H), 4.08 (t, J = 6.3 Hz, 4H), 2.05 (quint, J = 7.5 Hz, 4H), 1.91 (quint, J = 6.6 Hz, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.4, 159.9, 156.3, 147.8, 146.1, 145.1, 140.4, 138.6, 136.4, 132.14, 132.08, 131.2, 130.7, 129.5, 129.2, 128.7, 127.2, 126.9, 126.2, 125.4, 119.0, 118.9, 115.1, 107.5, 101.8, 83.2, 75.1, 68.0, 67.7, 64.2, 26.2, 25.8; IR (ATR): 1601, 1586, 1485 cm–1; HRMS (MALDI): calcd for C128H97N2O4 ([M + H]+), 1425.7424; found, 1725.7443. Data for 17a: mp 333.7–334.2 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 12H), 7.52 (d, J = 8.0 Hz, 12H), 7.45 (d, J = 8.6 Hz, 4H), 7.41 (t, J = 7.5 Hz, 12H), 7.30–7.33 (m, 22H); 13C{1H} NMR (126 MHz, CDCl3): δ 148.1, 145.2, 140.4, 138.8, 131.8, 131.4, 131.1, 128.8, 127.3, 127.0, 126.3, 119.4, 81.5, 74.1, 64.4; IR (ATR): 1599, 1486 cm–1; HRMS (MALDI): calcd for C90H63 ([M + H]+), 1143.4924; found, 1143.4961.

[2]Rotaxane (4b)

Following the general procedure A, 2 (77.3 mg, 0.10 mmol), 3b (168 mg, 0.25 mmol), K2CO3 (138 + 138 mg, 1.0 + 1.0 mmol), and I2 (25.4 + 25.4 mg, 0.10 + 0.10 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/1) to yield 4b (95 mg, 0.049 mmol, 49%) as a white solid; mp 191.8–195.9 °C; 1H NMR (500 MHz, CDCl3): δ 8.37 (d, J = 8.6 Hz, 4H), 8.22 (d, J = 8.0 Hz, 2H), 8.00 (d, J = 8.6 Hz, 2H), 7.72 (s, 2H), 7.57 (d, J = 6.9 Hz, 12H), 7.47 (d, J = 8.0 Hz, 12H), 7.44 (d, J = 8.6 Hz, 4H), 7.40 (t, J = 8.0 Hz, 12H), 7.37 (d, J = 8.6 Hz, 4H), 7.27–7.32 (m, 22H), 7.23 (d, J = 5.7 Hz, 4H), 7.16 (t, J = 8.0 Hz, 1H), 7.11 (d, J = 9.2 Hz, 4H), 7.02 (t, J = 2.3 Hz, 2H), 6.51 (dd, J = 2.3, 8.0 Hz, 2H), 4.10 (t, J = 7.5 Hz, 4H), 4.06 (t, J = 6.3 Hz, 4H), 1.99 (quint, J = 7.5 Hz, 4H), 1.88 (quint, J = 6.6 Hz, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.4, 159.8, 156.5, 147.2, 146.2, 145.3, 140.3, 138.6, 136.4, 132.5, 132.2, 131.5, 131.3, 131.0, 129.8, 129.2, 128.7, 127.3, 127.2, 126.9, 126.2, 125.4, 124.0, 121.0, 120.4, 119.3, 115.0, 107.1, 102.2, 92.2, 89.4, 83.0, 76.1, 67.9, 67.7, 64.2, 26.2, 25.7; IR (ATR): 1601, 1587, 1485, cm–1; HRMS (MALDI): calcd for C144H105N2O4 ([M + H]+), 1925.8069; found, 1925.8129.

[2]Rotaxane (4c) and Diyne (17c)

Following the general procedure A, 2 (15.5 mg, 0.020 mmol), 3c (33.1 mg, 0.050 mmol), K2CO3 (28 + 28 mg, 0.20 + 0.20 mmol), and I2 (5.1 + 5.1 mg, 0.020 + 0.020 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/1) to yield 4c (15 mg, 0.0077 mmol, 39%) as a white solid. The axle 17c (8.7 mg, 0.0066 mmol, 26%, based on 3c) was also isolated as a white solid. Data for 4c: mp 181.3–184.2 °C; 1H NMR (500 MHz, CDCl3): δ 8.36 (d, J = 8.0 Hz, 4H), 8.15 (d, J = 8.6 Hz, 2H), 7.93 (d, J = 8.0 Hz, 2H), 7.68 (s, 2H), 7.57 (d, J = 8.0 Hz, 12H), 7.47 (d, J = 7.5 Hz, 12H), 7.40 (t, J = 7.5 Hz, 12H), 7.38 (d, J = 7.5 Hz, 4H), 7.29–7.32 (m, 18H), 7.14 (d, J = 8.6 Hz, 8H), 7.10 (t, J = 8.6 Hz, 1H), 7.00 (s, 1H), 6.91 (t, J = 6.9 Hz, 8H), 6.49 (d, J = 8.6 Hz, 2H), 4.16 (t, J = 8.0 Hz, 4H), 4.10 (t, J = 6.9 Hz, 4H), 3.77 (s, 4H), 2.02 (quint, J = 7.5 Hz, 4H), 1.91 (quint, J = 6.9 Hz, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.5, 159.9, 156.4, 146.1, 145.8, 144.5, 142.1, 140.5, 138.5, 138.0, 136.4, 132.9, 132.1, 131.4, 131.1, 129.6, 129.1, 129.0, 128.7, 128.0, 127.2, 126.9, 126.1, 125.4, 119.1, 119.0, 115.0, 107.8, 101.7, 83.0, 74.7, 68.0, 67.7, 64.0, 41.2, 26.0, 25.9; IR (ATR): 1602, 1587, 1487 cm–1; HRMS (MALDI): calcd for C142H109N2O4 ([M + H]+), 1905.8382; found, 1905.8391. Data for 17c: mp 289.7–291.2 °C; 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 12H), 7.50 (d, J = 7.5 Hz, 12H), 7.44 (t, J = 8.0 Hz, 4H), 7.40 (t, J = 6.9 Hz, 12H), 7.29–7.34 (m, 18H), 7.23 (d, J = 7.5 Hz, 4H), 7.18 (d, J = 7.5 Hz, 4H), 7.08 (d, J = 8.0 Hz, 4H), 3.96 (s, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 145.8, 144.7, 142.5, 140.6, 138.6, 138.0, 132.6, 131.5, 131.3, 129.2, 128.7, 128.1, 127.2, 127.0, 126.1, 119.6, 81.5, 73.7, 64.1, 41.4; IR (ATR): 1487, 1427, 1411 cm–1; HRMS (MALDI): calcd for C104H75 ([M + H]+), 1323.5863; found, 1323.5844.

[2]Rotaxane (4d) and Diyne (17d)

Following the general procedure A, 2 (15.5 mg, 0.020 mmol), 3d (33.9 mg, 0.050 mmol), K2CO3 (28 + 28 mg, 0.20 + 0.20 mmol), and I2 (5.1 + 5.1 mg, 0.020 + 0.020 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/1) to yield 4d (11 mg, 0.0057 mmol, 28%) as a brown solid. The axle 17d (16.2 mg, 0.012 mmol, 48% based on 3d) was also isolated as a yellow solid. Data for 4d: mp 199.8–201.0 °C; 1H NMR (500 MHz, CDCl3): δ 8.48 (d, J = 9.2 Hz, 4H), 8.14 (d, J = 8.6 Hz, 2H), 7.98 (d, J = 8.6 Hz, 2H), 7.65 (s, 2H), 7.59 (d, J = 7.5 Hz, 12H), 7.50 (d, J = 8.6 Hz, 12H), 7.41 (t, J = 7.5 Hz, 12H), 7.30–7.32 (m, 22H), 7.25 (d, J = 6.9 Hz, 4H), 7.15 (d, J = 8.6 Hz, 4H), 7.12 (t, J = 8.0 Hz, 1H), 7.06 (1H, s), 6.88 (d, J = 8.6 Hz, 4H), 6.61 (d, J = 8.6 Hz, 4H), 6.51 (dd, J = 2.3, 8.6 Hz, 2H), 4.23 (t, J = 8.0 Hz, 4H), 4.18 (t, J = 6.9 Hz, 4H), 3.17 (s, 6H), 2.06 (quint, J = 7.5 Hz, 4H), 1.96 (quint, J = 6.9 Hz, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.6, 160.1, 156.1, 148.8, 146.0, 145.8, 145.3, 141.5, 140.5, 138.5, 136.3, 133.6, 132.0, 131.9, 131.4, 129.5, 129.1, 128.7, 127.2, 127.1, 126.9, 126.1, 125.3, 122.0, 118.7, 116.8, 115.1, 111.5, 108.3, 101.3, 83.7, 74.3, 68.1, 67.8, 63.8, 39.8, 26.0, 25.9; IR (ATR): 1590, 1505, 1485 cm–1; HRMS (MALDI): calcd for C142H111N4O4 ([M + H]+), 1935.8600; found, 1935.8669. Data for 17d: mp 250.9–252.0 °C; 1H NMR (500 MHz, CDCl3): δ 7.60 (d, J = 7.5 Hz, 12H), 7.53 (d, J = 8.0 Hz, 12H), 7.41 (t, J = 7.5 Hz, 12H), 7.35–7.37 (m, 16H), 7.31 (t, J = 7.5 Hz, 6H), 7.27 (d, J = 8.6 Hz, 4H), 7.06 (d, J = 8.6 Hz, 4H), 6.84 (d, J = 8.6 Hz, 4H), 3.33 (s, 6H); 13C{1H} NMR (126 MHz, CDCl3): δ 149.1, 145.8, 145.5, 142.0, 140.5, 138.6, 133.5, 132.2, 131.5, 128.8, 127.2, 127.0, 126.2, 122.6, 116.6, 111.8, 82.1, 73.1, 63.9, 40.1; IR (ATR): 1595, 1504, 1487 cm–1; HRMS (MALDI): calcd for C104H76N2 ([M]+), 1352.6003; found, 1352.5990.

[2]Rotaxane (4e)

A mixture of 2 (77.3 mg, 0.10 mmol), 3e (225 mg, 0.25 mmol 2.5 equiv), K2CO3 (51.8 mg, 0.375 mmol, 3.75 equiv), and I2 (31.7 mg, 0.125 mmol, 1.25 equiv) in dry THF (6.25 mL) was stirred at 60 °C under Ar for 48 h. The mixture was cooled to rt, and CH2Cl2 (17.5 mL), CH3CN (17.5 mL), KCN (52.1 mg, 0.80 mmol, 8.0 equiv), and water (10 mL) were added. After stirring at rt for 1 h, the mixture was extracted with CH2Cl2, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/AcOEt = 2/1) and GPC to yield 4e (112 mg, 0.047 mmol, 47%) as a white solid; mp 158.7–160.1 °C; 1H NMR (500 MHz, CDCl3): δ 8.39 (d, J = 7.5 Hz, 4H), 8.05 (d, J = 6.9 Hz, 2H), 7.69 (d, J = 8.6 Hz, 2H), 7.58–7.60 (m, 18H), 7.50 (d, J = 6.9 Hz, 12H), 7.40–7.44 (m, 16H), 7.29–7.34 (m, 18H), 7.23–7.25 (m, 8H), 7.15–7.17 (m, 8H), 7.09–7.11 (m, 5H), 7.05 (s, 1H), 6.79 (br, 8H), 6.49 (d, J = 8.0 Hz, 2H), 4.60 (s, 4H), 4.23 (d, J = 5.2 Hz, 4H), 4.15 (t, J = 7.5 Hz, 4H), 4.10 (t, J = 6.3 Hz, 4H), 3.98 (t, J = 5.7 Hz, 2H), 2.01 (quint, J = 6.9 Hz, 4H), 1.88 (quint, J = 6.3 Hz, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.4, 159.9, 156.2, 155.4, 146.0, 145.5, 144.9, 143.6, 141.2, 140.4, 139.5, 139.1, 138.6, 136.4, 132.9, 131.9, 131.5, 131.4, 129.6, 129.1, 128.7, 128.5, 127.5, 127.2, 127.2, 126.9, 126.6, 126.2, 125.9, 125.3, 124.8, 120.2, 119.8, 118.9, 115.0, 107.6, 101.8, 83.0, 75.0, 68.0, 67.7, 67.2, 63.9, 53.8, 47.1, 26.1, 25.8; IR (ATR): 1716, 1605, 1489 cm–1; HRMS (MALDI): calcd for C172H131N4O8 ([M + H]+), 2379.9961; found, 2379.9975.

[2]Rotaxane (4f) and Diyne (17f)

Following the general procedure A, 2 (40.2 mg, 0.052 mmol), 3f (86.3 mg, 0.13 mmol), K2CO3 (72 + 72 mg, 0.052 + 0.052 mmol), and I2 (13 + 13 mg, 0.52 + 0.52 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/2) to yield 4f (32 mg, 0.012 mmol, 24%) as a brown solid. The axle 17f (41 mg, 0.031 mmol, 48%, based on 3f) was also isolated as a brown solid. Data for 4f: mp 206.3–208.0 °C. 1H NMR (500 MHz, CDCl3): δ 8.26 (d, J = 8.0 Hz, 2H), 7.84 (d, J = 8.6 Hz, 2H), 7.78 (s, 2H), 7.68 (s, 2H), 7.61 (d, J = 8.6 Hz, 4H), 7.58 (d, J = 7.5 Hz, 12H), 7.48 (d, J = 8.6 Hz, 12H), 7.40 (t, J = 7.5 Hz, 12H), 7.29–7.32 (m, 18H), 7.19 (d, J = 8.6 Hz, 4H), 7.02–7.05 (m, 5H), 6.93 (d, J = 8.6 Hz, 4H), 6.87 (d, J = 8.6 Hz, 4H), 6.58–6.60 (m, 5H), 6.39 (dd, J = 2.3, 8.0 Hz, 2H), 3.92 (t, J = 6.3 Hz, 4H), 3.84 (t, J = 6.9 Hz, 4H), 1.75–1.81 (m, 8H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.3, 159.3, 159.2, 146.5, 146.1, 144.2, 140.6, 139.8, 138.9, 138.5, 136.6, 133.4, 132.7, 131.6, 131.5, 130.0, 129.8, 128.7, 128.5, 127.5, 127.2, 126.9, 126.0, 125.8, 121.9, 117.3, 115.5, 114.1, 111.4, 106.8, 101.8, 82.5, 72.9, 67.3, 63.7, 25.8, 25.4; IR (ATR): 3398, 1596, 1512, 1486 cm–1; HRMS (MALDI): calcd for C140H107N4O4 ([M + H]+), 1907.8287; found, 1907.8234. Data for 17f: mp 272.4–274.2 °C; 1H NMR (500 MHz, CDCl3): δ 7.60 (d, J = 7.5 Hz, 12H), 7.52 (d, J = 8.0 Hz, 12H), 7.41 (t, J = 7.5 Hz, 12H), 7.35–7.38 (m, 16H), 7.31 (t, J = 8.0 Hz, 6H), 7.23 (d, J = 8.0 Hz, 4H), 7.04 (d, J = 8.6 Hz, 4H), 6.97 (d, J = 8.6 Hz, 4H), 5.87 (s, 2H); 13C NMR (126 MHz, CDCl3): δ 145.9, 144.0, 140.5, 139.3, 138.6, 133.8, 132.1, 131.4, 128.7, 127.2, 126.9, 126.2, 118.0, 116.0, 112.9, 81.9, 73.1, 63.8; IR (ATR): 3398, 1595, 1505, 1484, cm–1; HRMS (MALDI): calcd for C102H73N2 ([M]+), 1324.5690; found, 1324.5662.

The synthesis of 4f was also studied by following procedure B. Compound 2 (86 mg, 0.11 mmol), 3f (184 mg, 0.28 mmol), K2CO3 (57 mg, 0.42 mmol), and I2 (35 mg, 0.14 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/2) to yield 4f (126 mg, 0.066 mmol, 60%) as a brown solid.

[2]Rotaxane (4g) and Diyne (17g)

Following the general procedure A, 2 (15.5 mg, 0.020 mmol), 3g (33.9 mg, 0.050 mmol), K2CO3 (28 + 28 mg, 0.20 + 0.20 mmol), and I2 (5.1 + 5.1 mg, 0.020 + 0.020 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/1) to yield 4g (2.5 mg, 0.0020 mmol, 6.4%) as a brown solid. The axle 17g (14 mg, 0.010 mmol, 41% based on 3g) was also isolated as a white solid. Data for 4g: mp 187.9–188.6 °C; 1H NMR (500 MHz, CDCl3): δ 8.24 (d, J = 8.0 Hz, 2H), 8.03 (d, J = 7.5 Hz, 4H), 7.92 (d, J = 8.6 Hz, 2H), 7.75 (s, 2H), 7.58 (d, J = 8.0 Hz, 12H), 7.48 (d, J = 7.5 Hz, 12H), 7.40 (t, J = 6.9 Hz, 12H), 7.30–7.33 (m, 18H), 7.02 (d, J = 8.2 Hz, 4H), 6.98 (d, J = 8.0 Hz, 5H), 6.79 (d, J = 8.0 Hz, 4H), 6.55 (d, J = 8.6 Hz, 4H), 6.35 (d, J = 7.5 Hz, 3H), 5.11 (s, 2H), 3.95 (t, J = 6.3 Hz, 4H), 3.90 (s, 4H), 3.70 (t, J = 5.7 Hz, 4H), 1.76 (m, 8H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.3, 159.6, 158.4, 146.7, 146.61, 146.55, 141.7, 140.8, 138.5, 136.7, 135.1, 133.0, 132.8, 131.9, 131.6, 130.3, 129.7, 128.9, 127.6, 127.4, 127.3, 127.1, 126.1, 125.9, 120.9, 120.1, 114.7, 112.2, 107.5, 100.9, 82.2, 74.2, 67.5, 67.4, 63.7, 48.1, 25.8, 25.5; IR (ATR): 3420, 3331, 1605, 1586, 1515, 1487 cm–1; HRMS (MALDI): calcd for C142H111N4O4 ([M + H]+), 1935.8600; found, 1935.8665. Data for 17g: mp 249.7–250.9 °C;1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 12H), 7.50–7.47 (m, 16H), 7.40 (t, J = 7.5 Hz, 12H), 7.34–7.29 (m, 22H), 7.08 (d, J = 8.6 Hz, 4H), 6.54 (d, J = 8.6 Hz, 4H), 4.33 (s, 4H), 4.08 (br, 2H); 13C{1H} NMR (100 MHz, CDCl3): δ 146.3, 145.8, 140.6, 140.4, 138.3, 135.9, 132.6, 132.4, 132.0, 131.5, 128.7, 127.3, 127.1, 126.9, 126.0, 122.2, 111.9, 93.9, 63.6, 48.2; IR (ATR): 3412, 1608, 1513, 1485 cm–1; HRMS (MALDI): calcd for C104H77N2 ([M + H]+), 1353.6081; found, 1353.6067.

[2]Rotaxane (4h) and Diyne (17h)

Following the general procedure A, 2 (77.3 mg, 0.10 mmol), 3h (173 mg, 0.25 mmol), K2CO3 (138 + 138 mg, 1.0 + 1.0 mmol), and I2 (25.4 + 25.4 mg, 0.10 + 0.10 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/2) to yield 4h (91 mg, 0.046 mmol, 46%) as a yellow solid. The axle 17h (42 mg, 0.030 mmol, 80%, based on 3h) was also isolated as a white solid. Data for 4h: mp 214.2–216.6 °C; 1H NMR (500 MHz, CDCl3): δ 9.42 (s, 2H), 8.27 (d, J = 8.6 Hz, 2H), 7.97 (d, J = 8.0 Hz, 4H), 7.82 (s, 2H), 7.72 (d, J = 8.0 Hz, 2H), 7.58 (d, J = 8.0 Hz, 12H), 7.48–7.51 (m, 16H), 7.40 (t, J = 8.0 Hz, 12H), 7.27–7.35 (m, 26H), 7.10 (d, J = 8.6 Hz, 4H), 7.06 (t, J = 8.6 Hz, 1H), 6.93 (s, 1H), 6.57 (d, J = 8.6 Hz, 4H), 6.43 (dd, J = 2.3, 8.0 Hz, 2H), 4.04 (t, J = 5.7 Hz, 4H), 3.98 (t, J = 6.3 Hz, 4H), 1.83–1.87 (m, 8H); 13C{1H} NMR (126 MHz, CDCl3): δ 164.4, 160.5, 159.5, 159.1, 146.1, 145.9, 142.1, 140.5, 138.5, 136.6, 136.3, 135.3, 132.5, 132.0, 131.4, 131.1, 129.6, 129.5, 128.7, 127.6, 127.5, 127.2, 126.9, 126.1, 125.9, 124.2, 122.1, 119.6, 114.2, 107.3, 100.9, 81.8, 75.5, 67.3, 67.2, 63.9, 25.5, 25.3; IR (ATR): 1667, 1601, 1511, 1486 cm–1; HRMS (MALDI): calcd for C142H107N4O6 ([M + H]+), 1963.8185; found, 1963.8180. Data for 17h: mp 260.6–262.6 °C;1H NMR (500 MHz, CDCl3): δ 7.83 (d, J = 8.6 Hz, 4H), 7.78 (s, 2H), 7.61 (d, J = 8.6 Hz, 4H), 7.60 (d, J = 8.0 Hz, 12H), 7.52 (d, J = 8.0 Hz, 12H), 7.41 (t, J = 7.5 Hz, 12H), 7.30–7.37 (m, 22H); 13C{1H} NMR (126 MHz, CDCl3): δ 164.7, 145.7, 143.3, 140.5, 138.7, 135.5, 135.3, 132.9, 131.8, 131.4, 128.7, 127.2, 127.1, 127.0, 126.3, 125.1, 119.4, 81.6, 76.1, 64.0; IR (ATR): 3439, 1682, 1600, 1519, 1487 cm–1; HRMS (MALDI): calcd for C104H73N2O2 ([M + H]+), 1381.5667; found, 1381.5610.

[2]Rotaxane (4i) and Diyne (17i)

Following the general procedure A, 2 (77.3 mg, 0.10 mmol), 3i (179 mg, 0.25 mmol), K2CO3 (138 + 138 mg, 1.0 + 1.0 mmol), and I2 (25.4 + 25.4 mg, 0.10 + 0.10 mmol) were used. The residue was purified by silica gel column chromatography (hexane/CHCl3 = 1/2) to yield 4i (98 mg, 0.048 mmol, 48%) as a white solid. The axle 17i (62 mg, 0.043 mmol, 35% based on 3i) was also isolated as a yellow solid. Data for 4i: mp 219.2–225.7 °C; 1H NMR (500 MHz, CDCl3): δ 9.34 (s, 2H), 8.25 (d, J = 8.0 Hz, 2H), 7.91 (d, J = 8.0 Hz, 4H), 7.80 (s, 2H), 7.72–7.77 (m, 10H), 7.59 (d, J = 7.5 Hz, 12H), 7.52 (d, J = 8.6 Hz, 12H), 7.41 (t, J = 8.0 Hz, 12H), 7.30–7.36 (m, 26H), 7.16 (t, J = 2.3 Hz, 1H), 7.07 (t, J = 8.6 Hz, 1H), 6.48 (dd, J = 2.3, 8.6 Hz, 2H), 6.38 (d, J = 8.6 Hz, 4H), 4.14 (t, J = 6.3 Hz, 4H), 3.84 (t, J = 6.9 Hz, 4H), 1.84 (quint, J = 7.5 Hz, 4H), 1.77 (quint, J = 6.9 Hz, 4H); 13C{1H} NMR (126 MHz, CDCl3): δ 160.6, 159.2, 159.1, 147.0, 146.9, 146.7, 145.3, 140.4, 138.8, 136.5, 134.7, 133.0, 132.7, 131.8, 131.35, 131.28, 129.5, 129.4, 128.8, 127.4, 127.3, 126.9, 126.4, 125.8, 125.5, 121.5, 120.8, 120.5, 119.3, 114.1, 108.0, 100.6, 82.1, 74.6, 67.3, 67.1, 64.1, 25.24, 25.22; IR (ATR): 1601, 1586, 1516, 1483 cm–1; HRMS (MALDI): calcd for C144H107N8O4 ([M + H]+), 2011.8410; found, 2011.8481. Data for 17i: mp 234.5–236.8 °C; 1H NMR (500 MHz, CDCl3): δ 8.19 (s, 2H), 7.88 (d, J = 6.9 Hz, 4H), 7.71 (d, J = 7.5 Hz, 4H), 7.61–7.60 (m, 16H), 7.56–7.53 (m, 16H), 7.42 (t, J = 7.5 Hz, 12H), 7.38 (d, J = 7.5 Hz, 12H), 7.33 (t, J = 7.5 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.0, 147.5, 145.2, 140.4, 139.0, 134.8, 133.1, 132.5, 131.4, 131.0, 128.8, 127.4, 127.0, 126.4, 125.7, 119.8, 118.0, 74.9, 64.2 (two signals are missing); IR (ATR): 1600, 1515, 1485 cm–1; HRMS (MALDI): calcd for C106H73N6 ([M + H]+), 1429.5891; found, 1429.5851.

Synthesis of 4g by the Removal of the Fmoc Group from 4e

A solution of 4e (72 mg, 0.030 mmol) in diethylamine (0.10 mL), acetonitrile (2.0 mL), and dichloromethane (8.0 mL) was stirred at rt under Ar for 4 h. To the mixture was added water, and the mixture was extracted with CH2Cl2 (3 × 3 mL). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/AcOEt = 1/1) and GPC to yield 4g (49 mg, 0.025 mmol, 84%) as a white solid.

Preparation and Observation of the 1H NMR Spectrum of 4f-

A solution of 4f (27 mg, 0.014 mmol) in CH3OD (99 atom % D, 1.2 mL) and anhydrous dichloromethane (1.2 mL) was stirred at rt under Ar overnight. Volatiles were removed under reduced pressure to yield the desired deuterated compound, 4f- (26 mg, 0.014 mmol, quint, 78 atom % D of the N–D bond, estimated by 1H NMR in CDCl3) as a light yellow solid.

In order to reduce the deuteration loss due to water and possible residual acidic impurities in the solvent used for recording NMR, it was imperative to include a simple pre-treatment for these solvents. NMR solvents (CDCl3 for confirming deuteration and deuterated toluene-d8 for VT NMR experiments) were thoroughly washed with equal volume of D2O followed by drying over sodium sulfate before use.

X-ray Diffraction Studies

A suitable single crystal was selected in Fomblin Y perfluoropolyether (HVAC 140/13) at ambient temperature. All diffraction data were collected at −173 °C on a Bruker Apex II Ultra X-ray diffractometer equipped with a Mo Kα radiation (λ = 0.71073 Å) source. Intensity data were processed using the Apex3 software suite. The solution of the structures and the corresponding refinements were carried out using the Yadokari-XG[31] graphical interface. The positions of the non-hydrogen atoms were determined by using the SHELXT-2014/5 and 2018/2[32] program and refined on F2 by the full-matrix least-squares technique using the SHELXL-2018/3[33] program. All non-hydrogen atoms were refined with anisotropic thermal parameters, while all hydrogen atoms were placed using AFIX instructions.

Compound 4a(a): C128H96N2O4·2(toluene)·(hexane). Single crystals for X-ray diffraction were grown from toluene/hexane solution. The diffraction data are summarized in Table S1.

Compound 4a(b): C128H96N2O4·CHCl3·(solvents). Single crystals for X-ray diffraction were grown from CHCl3/MTBE solution. Accessible voids were found in the unit cell. Attempts to model the solvent molecules (CHCl3, MTBE, and/or H2O) were not successful due to heavy disorder of the molecules. The diffuse electron density associated with the solvent molecules was removed by the PLATON/SQUEEZE[34] program. The diffraction data are summarized in Table S2.