Metal-Free C-H Functionalization of Allenamides: An Access to Branched Allylic Esters.

A regioselective acyloxylation with carboxylic acids at the proximal carbon of allenamides by an N-iodosuccinimide-mediated C-H functionalization is reported. The reaction proceeds rapidly, is scalable to a gram scale, and displays a broad substrate scope, providing an efficient and practical protocol for the synthesis of branched allylic esters. Notably, protected amino acids were tolerated under the reaction conditions and afforded allylic amino acid esters in moderate yields.

Introduction

Allylic esters have garnered increasing attention because of their presence in bioactive and medicinally relevant molecules.[1] They are widely present in bioactive natural products such as grandiuvarone A and albanol A (Figure ), which are isolated from the barks of Uvaria grandiflora and Uvaria alba, respectively, and are known to exhibit antileishmanial, cytostatic, and antiproliferative activities. Furthermore, branched allylic alcohols and their ester derivatives are important building blocks in organic synthesis.[2]

Figure 1

Bioactive molecules comprising the allylic ester unit.

Traditional synthetic methods for the preparation of allyl esters involve the reaction of an acid or its derivatives (acyl chlorides and anhydrides) with the corresponding allylic alcohols.[3] However, these approaches suffer from limited substrate scope and harsh reaction conditions. The transition-metal-catalyzed direct oxidative esterification of allylic sp3 C–H bonds has emerged as one of the most important strategies for the synthesis of branched allylic esters and is an important alternative to the traditional synthetic approaches. Several methodologies relying on this approach have been reported for the synthesis of allylic esters. Although palladium-,[4] copper-,[5] and iron-catalyzed[6] esterifications of allylic sp3 C–H bonds have been reported, they suffer from poor atom economy because of the necessity for the use of stoichiometric equivalents of oxidants. An elegant alternate approach for the synthesis of allylic esters via a redox-neutral and atom-economic rhodium-catalyzed coupling of terminal alkynes with carboxylic acids has been reported recently.[7] Allenes are an easily accessible and remarkably stable substrate class, and Yamamoto,[8] Krische,[9] and Breit[10] reported the palladium-, iridium-, and rhodium-catalyzed coupling of allenes with carboxylic acids for synthesizing linear and branched allylic esters. Although these methods are powerful synthetic transformations, they require the use of transition metals, and in many cases the corresponding ligands in the catalytic system, which make them expensive and less ecofriendly. Considering these wide arrays of available approaches, a metal-free approach to allylic sp3 C–H bond esterification would obviate many of the aforementioned disadvantages. However, reports on such metal-free allylic sp3 C–H esterification are limited, and only one example using Bu4NI as a catalyst was reported,[11] which further highlights the necessity for the development of a straightforward and low-cost metal-free allylic sp3 C–H esterification protocol.

Allenamides have recently emerged as important synthetic intermediates and participate in diverse and interesting transformations.[12] We have reported the halogen-mediated intermolecular coupling reactions of allenamides[13] and recently reported a related methodology for the metal-free synthesis of allylic ethers by the regioselective alkoxylation of allenamides with alcohols (Scheme a).[14] However, this reaction required the use of low-boiling alcohol nucleophiles as the reaction solvents, which limited the substrate scope for the transformation and promoted us to examine the allylic substitution using carboxylic acids as the nucleophiles. We present herein a metal-free synthesis of branched allylic esters with broad functional group tolerance by the N-iodosuccinimide (NIS)-mediated regioselective acyloxylation at the proximal carbon of allenamides (Scheme b).

Scheme 1

NIS-Mediated Regioselective Alkoxylation and Acyloxylation of Allenamides

Results and Discussion

On the basis of our previous results on the regioselective 1,2-additions of alcohols to allenamides, we began our studies by exploring the reaction between phenyl allenamide 1a and acetic acid 2a, and the optimization results of the study are summarized in Table . Employing the conditions from our previous study, upon treating phenyl allenamide 1a with 1.05 equiv of NIS in 3 mL of acetic acid, the acyloxylated product 4aa was isolated in 86% yield (Table , entry 1). When the reaction was performed with 1 equiv of acetic acid 2a in 3 mL of dichloromethane (DCM), the branched allylic ester 4aa was obtained in 52% yield along with the linear allylic ester 5a in 20% yield (Table , entry 2). In an attempt to increase the nucleophilicity of acetic acid 2a, 2 equiv of K2CO3 was added to the reaction mixture, which delivered the branched allylic ester in 27% yield (Table , entry 3). After screening various equivalent ratios of 1a and 2a, we found that the best regioselectivity and yield of the branched allylic ester 4a were obtained with the use of 6 equiv of 2a (Figure ). Various iodine sources were evaluated next, and compared to other iodine sources such as N-iodophthalimide (3d) and elemental iodine (3g), NIS proved to be the best choice for generating the target compound 4aa. Encouraged by these results, we examined the related N-haloimides for this transformation. When N-bromosuccinimide (3b) and N-bromophthalimide (3e) were used in this reaction, the branched allylic ester 4b was isolated in 50 and 47% yields, respectively (Table , entries 5 and 8). N-Chlorosuccinimide (3c) and N-chlorophthalimide (3f) were less reactive and delivered the corresponding product 4c in 55 and 34% yields, respectively. Subsequent solvent screening studies indicated an increase in the yield of 4aa to 85% when CH3CN was used as the solvent, whereas 1,2-dichloroethane (DCE), CHCl3, toluene, and acetone were not as effective under the reaction conditions (Table , entry 11–15). Furthermore, the control experiment (Table , entry 16) showed that no acyloxylated product was obtained in the absence of NIS, revealing the importance of the iodine sources.

Table 1

Optimization of Halogen-Mediated Acyloxylation of Allenamide 1a with Acetic Acid 2aa

entry	1a/2a	halogen reagent	solvent	yield 4/5 (%)
1b		3a	acetic acid	86/0
2	1/1	3a	DCM	52/20
3c	1/1	3a	DCM	27/0
4d	1/6	3a	DCM	79/7
5	1/6	3b	DCM	50/12
6e	1/6	3c	DCM	55/22
7f	1/6	3d	DCM	38/0
8	1/6	3e	DCM	47/0
9	1/6	3f	DCM	34/0
10	1/6	3g	DCM	trace
11	1/6	3a	DCE	62/16
12	1/6	3a	CHCl3	69/23
13	1/6	3a	CH3CN	85/0
14	1/6	3a	toluene	69/5
15	1/6	3a	acetone	77/10
16	1/6		CH3CN	NR

Unless stated otherwise, all reactions were carried out with 1a (0.1 mmol) and 3 (0.105 mmol) in 3 mL of solvent at rt and are complete within 5 min.

The reaction was carried out with 3 mL of acetic acid as the solvent.

1.1 equiv K2CO3 was added.

Best ratio of 1a/2a equiv.

1a was consumed within 1.5 h.

1a was consumed within 9 h.

Figure 2

Optimization of 1a/2a equiv ratio.

Employing the optimized conditions (Table , entry 13), we investigated the scope of the carboxylic acid substrates in the reaction (Table ) and were pleased to find the efficient formation of the desired products in good yields for all acids which were evaluated. Aliphatic carboxylic acids (linear and branched) worked well and afforded the desired allylic esters (4aa–4ae) in 62–85% yields. Similarly, cyclic carboxylic acids afforded the branched allylic esters (4af–4ai) in 63–84% yields. Furthermore, the sterically hindered adamantyl carboxylic acid 2j was a suitable substrate and furnished the corresponding product in 63% yield. In addition to the unsubstituted benzoic acid 2k, both electron-rich and electron-poor aromatic carboxylic acids were suitable reaction partners (4al–4ap). The 2-methyl- and 3-fluoro-substituted benzoic acids also provided the corresponding products 4aq and 4ar in 68% yield, respectively. The 2-naphthyl carboxylic acid 2s and cinnamic acid 2t were also tolerated under the reaction conditions and afforded the desired allylic esters in 72 and 69% yields, respectively.

Table 2

NIS-Mediated Acyloxylation of Allenamide 1a with Various Carboxylic Acidsa

Conditions: 1a (0.1 mmol), 2a (0.6 mmol), NIS (0.105 mmol), CH3CN (3 mL), rt, within 5 min.

Having studied the scope of the carboxylic acids in this reaction, we turned our attention to the investigation of the allenamide scope (Table ). Several para- and meta-substituted phenyl allenamides were investigated first (1b–1h). Phenyl allenamides bearing electron-rich substituents worked better in this reaction and afforded the desired allylic esters 4ba and 4ca in 89 and 81% yields, respectively. The initial step of this reaction was proposed to be the electrophilic halogenation between the iodine electrophile and the π system of the allenamide. The reactions with 3,5-dimethoxyl- and 2-naphthyl-substituted allenamides 1i and 1j proceeded smoothly and provided 4ia and 4ja in 72 and 78% yields, respectively. Moreover, the molecular structure of the branched allylic ester 4ia was unambiguously determined by single-crystal X-ray diffraction (Figure ).[15] Interestingly, when trimethyl phenyl allenamide was used as the reactant, the linear allylic ester was isolated as the sole product in 56% yield, possibly because of the increased steric hindrance of the substrate. Next, benzyl allenamides 1k–1p were employed as substrates under optimized reaction conditions, and the para-methyl- and bromo-substituted benzyl allenamide 1l and 1p gave the allylic esters 4la and 4pa in 91 and 84% yields, respectively. Both electron-rich and electron-poor benzyl allenamides 1k and 1m–1o furnished the desired products in about 70% yields, exhibiting no obvious substituent effects. We investigated next the reactivity of different allenamides bearing aliphatic substituents under the optimized conditions. Both phenethyl- and n-butyl-substituted allenamides produced products 4qa and 4ra in 72 and 48% yields, respectively. The reaction was also efficient when the tosyl group in the allenamides was substituted with the acyl and mesyl amino protecting groups and delivered 4sa and 4ta in 74 and 81% yields, respectively. Furthermore, 2-oxazolidinone allenamide 1u also provided the corresponding product 4ua in 48% yield.

Table 3

NIS-Mediated Acyloxylation of Various Allenamides 1 with Acetic Acid 2aa

Conditions: 1a (0.1 mmol), 2a (0.6 mmol), NIS (0.105 mmol), CH3CN (3 mL), rt, within 5 min.

Figure 3

X-ray structure of 4ia.

To establish the practicality of this reaction, a gram-scale synthesis of the branched allylic ester 4aa was carried out. When 1.42 g of allenamide 1a (5.0 mmol) was used, 1.95 g of the desired product 4aa was obtained in 83% yield within 5 min, indicating the facile scalability of the transformation to the gram scale without loss in efficiency (Scheme ). To further demonstrate the potential applications of this protocol, 1a was reacted with N-Boc-l-Phe, N-Ac-l-Phe, and N-Boc-l-Tyr, upon which the corresponding products 6, 7, and 8 were isolated in moderate yields in a 1:1 dr.

Scheme 2

Gram-Scale Synthesis and Synthetic Applications

In summary, we demonstrated the first intermolecular addition of carboxylic acids to the proximal carbon of allenamides toward the formation of highly useful branched allylic esters under superior regioselectivity by employing a simple and commercially available iodine reagent. This reaction proceeds rapidly, is scalable up to a gram scale, and tolerates a broad scope of substrates. Notably, the protected amino acids were compatible and furnished the desired allylic amino acid esters in moderate yields. A further exploration of potential applications and studies to extend this interesting synthetic methodology is currently underway.

Experimental Section

General Conditions

All reactions were performed using Schlenk tubes, septa, and syringes without the protection of nitrogen. Tetrahydrofuran, toluene, DCM, and DCE were freshly distilled over sodium/benzophenone and calcium hydride, respectively. Commercial reagents were used as supplied or were purified by standard techniques where necessary. Column chromatography was performed using a 200–300 mesh silica gel (Qingdao Haiyang Chemical Co., Ltd., silica gel F254) with an appropriate solvent system, as determined by thin-layer chromatography (TLC) analysis using UV light and KMnO4 stain to visualize the reaction components. Melting points were determined using a WRS-1B digital melting point instrument. IR spectra were recorded on a Nicoletisso Fourier transform infrared spectrometer using KBr disks. Unless otherwise noted, nuclear magnetic resonance spectra were recorded at room temperature on an Agilent 400 MHz spectrometer using CDCl3 as the solvent and tetramethylsilane (TMS) as the internal reference. Chemical shifts for 13C nuclear magnetic resonance (NMR) spectra were recorded in parts per million relative to TMS using the central peak of deuterochloroform (77.0 ppm) as the internal standard (see Supporting Information). High-resolution mass spectrometry (HRMS) was performed using a Bruker Daltonics Bio time-of-flight (TOF) mass spectrometer.

Allenamides 1a–1u were prepared according to the published methods.[16] Carboxylic acids were obtained commercially and used without further purification.

General Procedure for NIS-Mediated Acyloxylation of Allenamide 1a with Acetic Acid 2a

To a Schlenk tube were added allenamide 1a (0.1 mmol, 28.5 mg), acetic acid 2a (6.0 equiv, 34 μL), NIS (1.05 equiv, 23.5 mg), and CH3CN (anhydrous, 3 mL). Then, the reaction mixture was stirred at room temperature (rt) for 5 min until the complete consumption of the starting material as monitored by TLC. The mixture was then washed with saturated sodium bicarbonate solution (5 mL), extracted with DCM (3 mL × 2), and dried over anhydrous Na2SO4. The concentration of the reaction mixture in vacuo followed by purification through flash chromatography on a silica gel column (hexane/EtOAc = 5/1 as the eluent) afforded 4aa (40.0 mg, 85% yield) as a white solid.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Acetate (4aa)

Yield 85% (40.0 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 103.6–108.2 °C; IR (neat, cm–1): 3452, 1660, 1630, 1170, 1090, 745, 702; 1H NMR (400 MHz, CDCl3): δ 7.52 (d, J = 8.1 Hz, 2H), 7.36 (t, J = 7.1 Hz, 1H), 7.31 (d, J = 7.7 Hz, 2H), 7.26–7.24 (m, 5H), 6.03 (s, 1H), 5.72 (s, 1H), 2.44 (s, 3H), 1.99 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 144.0, 136.1, 134.5, 131.5, 129.2, 129.1, 128.9, 128.6, 128.1, 101.2, 84.9, 21.6, 20.6; HRMS (ESI) m/z: calcd for C18H18INO4SNa+ (M + Na)+, 493.9893; found, 493.9899.

2-Bromo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Acetate (4b)

Yield 50% (21.2 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 120.5–120.9 °C; IR (neat, cm–1): 3468, 2935, 2378, 1760, 1365, 1249, 1170, 1088, 700, 666; 1H NMR (400 MHz, CDCl3): δ 7.43 (d, J = 7.9 Hz, 2H), 7.28–7.23 (m, 1H), 7.22–7.12 (m, 5H), 7.10 (d, J = 7.5 Hz, 2H), 5.45 (s, 1H), 5.32 (s, 1H), 2.33 (s, 3H), 1.90 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 144.0, 136.2, 134.5, 131.4, 129.3, 129.2, 128.6, 128.0, 125.0, 120.5, 82.9, 21.6, 20.6. HRMS (ESI) m/z: calcd for C18H18BrNO4SNa+ (M + Na)+, 446.0032: found, 446.0038.

2-Chloro-1-(4-methyl-N-phenylphenylsulfonamido)allyl Acetate (4c)

Yield 55% (20.8 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 103.4–104.3 °C; IR (neat, cm–1): 3480, 2935, 2376, 1761, 1353, 1167, 1091, 700, 667; 1H NMR (400 MHz, CDCl3): δ 7.44 (d, J = 8.2 Hz, 2H), 7.26 (t, J = 7.3 Hz, 1H), 7.19 (t, J = 7.5 Hz, 2H), 7.15 (d, J = 8.9 Hz, 3H), 7.07 (d, J = 7.6 Hz, 2H), 5.09 (s, 1H), 5.02 (s, 1H), 2.33 (s, 3H), 1.91 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 144.0, 136.3, 134.5, 134.4, 131.4, 129.3, 129.2, 128.6, 128.0, 116.0, 81.8, 21.6, 20.7. HRMS (ESI) m/z: calcd for C18H18Cl4SNa+ (M + Na)+, 402.0537; found, 402.0540.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Propionate (4ab)

Yield 77% (37.5 mg); R = 0.31 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 117.7–118.7 °C; IR (neat, cm–1): 3463, 2938, 2383, 1642, 1360, 1081, 745; 1H NMR (400 MHz, CDCl3): δ 7.45 (d, J = 7.7 Hz, 2H), 7.31–7.27 (m, 1H), 7.24 (d, J = 7.4 Hz, 2H), 7.21–7.16 (m, 5H), 5.94 (s, 1H), 5.64 (s, 1H), 2.36 (s, 3H), 2.24–2.10 (m, 2H), 1.03 (t, J = 7.5 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 171.4, 144.0, 136.2, 134.5, 131.5, 129.3, 129.1, 128.8, 128.5, 128.1, 101.4, 84.7, 27.3, 21.6, 8.7; HRMS (ESI) m/z: calcd for C19H20INO4SNa+ (M + Na)+, 508.0050; found, 508.0051.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Butyrate (4ac)

Yield 67% (33.5 mg); R = 0.12 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 97.7–99.1 °C; IR (neat, cm–1): 3453, 1646, 1271, 1168, 745, 705; 1H NMR (400 MHz, CDCl3): δ 7.53 (d, J = 7.9 Hz, 2H), 7.38–7.34 (m, 1H), 7.31 (d, J = 7.6 Hz, 2H), 7.27 (m, 4H), 7.24 (s, 1H), 6.01 (s, 1H), 5.71 (s, 1H), 2.43 (s, 3H), 2.20 (dd, J = 16.1, 8.0 Hz, 2H), 1.61 (dd, J = 14.7, 7.3 Hz, 2H), 0.94 (t, J = 7.3 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 170.7, 144.0, 136.2, 134.5, 131.5, 129.3, 129.1, 128.8, 128.5, 128.1, 101.5, 84.7, 35.7, 21.6, 18.00, 13.7; HRMS (ESI) m/z: calcd for C20H22INO4SNa+ (M + Na)+, 522.0206; found, 522.0209.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Isobutyrate (4ad)

Yield 62% (30.7 mg); R = 0.5 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 101.7–102.0 °C; IR (neat, cm–1): 3432, 3141, 1647, 1625, 1406, 1075, 600, 574; 1H NMR (400 MHz, CDCl3): δ 7.54 (d, J = 8.2 Hz, 2H), 7.39–7.35 (m, 1H), 7.31 (t, J = 7.4 Hz, 2H), 7.27–7.23 (m, 4H), 6.00 (s, 1H), 5.71 (s, 1H), 2.46 (q, J = 7.0 Hz), 2.42 (s, 3H), 1.13 (s, 3H), 1.11 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 173.9, 144.0, 136.3, 134.5, 131.6, 129.3, 129.1, 128.7, 128.6, 128.1, 101.7, 84.6, 33.8, 21.6, 18.7, 18.5; HRMS (ESI) m/z: calcd for C20H22INO4SNa+ (M + Na)+, 522.0206; found, 522.0208.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Nonanoate (4ae)

Yield 66% (37.5 mg); R = 0.55 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 96.2–97.5 °C; IR (neat, cm–1): 3463, 2937, 2372, 2350, 1757, 1172, 1079, 744, 672; 1H NMR (400 MHz, CDCl3): δ 7.53 (d, J = 7.7 Hz, 2H), 7.35 (d, J = 6.5 Hz, 1H), 7.31 (d, J = 7.4 Hz, 2H), 7.26–7.23 (m, 5H), 6.01 (s, 1H), 5.71 (s, 1H), 2.43 (s, 3H), 2.27–2.13 (m, 2H), 1.59–1.52 (m, 2H), 1.28 (br, 10H), 0.89 (t, J = 6.5 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 170.9, 143.9, 136.3, 134.6, 131.6, 129.3, 129.1, 128.8, 128.6, 128.1, 101.6, 84.7, 33.9, 31.8, 29.2, 29.1, 29.08, 24.5, 22.6, 21.6, 14.1; HRMS (ESI) m/z: calcd for C25H32INO4SNa+ (M + Na)+, 592.0989; found, 592.0988.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Cyclopropanecarboxylate (4af)

Yield 84% (41.7 mg); R = 0.28 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 137.9–138.8 °C; IR (neat, cm–1): 3464, 2257, 1662, 1641, 1076, 744; 1H NMR (400 MHz, CDCl3): δ 7.52 (d, J = 7.6 Hz, 2H), 7.36 (d, J = 6.9 Hz, 1H), 7.32 (d, J = 7.0 Hz, 2H), 7.29–7.24 (m, 5H), 6.05 (s, 1H), 5.72 (s, 1H), 2.44 (s, 3H), 1.54–1.51 (m, 1H), 1.07–1.06 (m, 1H), 0.95–0.90 (m, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 172.1, 143.9, 136.1, 134.5, 131.5, 129.3, 129.1, 128.9, 128.5, 128.1, 101.3, 84.8, 21.6, 12.5, 8.9, 8.7; HRMS (ESI) m/z: calcd for C20H20INO4SNa+ (M + Na)+, 520.0050; found, 520.0046.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Cyclobutanecarboxylate (4ag)

Yield 63% (32.2 mg); R = 0.34 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 113.9–114.6 °C; IR (neat, cm–1): 3433, 2936, 2383, 1635, 1363, 1166, 1085, 702; 1H NMR (400 MHz, CDCl3): δ 7.53 (d, J = 8.1 Hz, 2H), 7.38–7.34 (m, 1H), 7.31 (d, J = 7.7 Hz, 2H), 7.29–7.23 (m, 5H), 6.00 (s, 1H), 5.71 (s, 1H), 3.07–2.98 (m, 2H), 2.43 (s, 3H), 2.22–2.12 (m, 4H), 2.01–1.94 (m, 1H), 1.90–1.86 (m, 1H); 13C{1H} NMR (100 MHz, CDCl3): δ 172.4, 144.0, 136.2, 134.5, 131.5, 129.3, 129.1, 128.8, 128.6, 128.1, 101.6, 84.5, 37.5, 25.0, 24.8, 21.6, 18.4; HRMS (ESI) m/z: calcd for C21H22INO4SNa+ (M + Na)+, 534.0206; found, 534.0208.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Cyclopentanecarboxylate (4ah)

Yield 63% (33.0 mg); R = 0.16 (SiO2; hexanes/ethyl acetate, 10:1); colorless liquid; IR (neat, cm–1): 3471, 2934, 1711, 1604, 1500, 1355, 1094, 744; 1H NMR (400 MHz, CDCl3): δ 7.54 (d, J = 7.5 Hz, 2H), 7.36 (d, J = 7.1 Hz, 1H), 7.31 (t, J = 7.4 Hz, 2H), 7.28–7.24 (m, 4H), 7.23 (s, 1H), 6.01 (s, 1H), 5.71 (s, 1H), 2.66–2.58 (m, 1H), 2.42 (s, 3H), 1.87–1.79 (m, 2H), 1.73–1.65 (m, 4H), 1.61–1.56 (m, 2H). 13C{1H} NMR (100 MHz, CDCl3): δ 173.6, 143.9, 136.3, 134.6, 131.6, 129.3, 129.1, 128.7, 128.6, 128.1, 101.8, 84.5, 43.4, 29.8, 29.4, 25.8, 25.7, 21.6. HRMS (ESI) m/z: calcd for C22H24INO4SNa+ (M + Na)+, 548.03630; found, 548.0364.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Cyclohexanecarboxylate (4ai)

Yield 68% (36.6 mg); R = 0.33 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 107.5–107.9 °C; IR (neat, cm–1): 3458, 2378, 1678, 1641, 1270, 1080, 744; 1H NMR (400 MHz, CDCl3): δ 7.54 (d, J = 8.2 Hz, 2H), 7.39–7.35 (m, 1H), 7.32 (t, J = 7.4 Hz, 2H), 7.27–7.23 (m, 5H), 6.00 (s, 1H), 5.70 (s, 1H), 2.43 (s, 3H), 2.20–2.15 (m, 1H), 1.85–1.73 (m, 4H), 1.67–1.62 (m, 1H), 1.38–1.23 (m, 5H). 13C{1H} NMR (100 MHz, CDCl3): δ 173.0, 143.9, 136.4, 134.6, 131.5, 129.3, 129.1, 128.8, 128.6, 128.1, 101.7, 84.6, 42.8, 28.8, 28.6, 25.6, 25.3, 25.26, 21.6. HRMS (ESI) m/z: calcd for C23H26INO4SNa+ (M + Na)+, 562.0519; found, 562.0519.

(3R,5R,7R)-2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Adamantane-1-carboxylate (4aj)

Yield 63% (38.0 mg); R = 0.26 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 99.7–101.2 °C; IR (neat, cm–1): 3474, 2929, 2368, 1661, 1630, 1171, 1055, 743; 1H NMR (400 MHz, CDCl3): δ 7.56 (d, J = 8.1 Hz, 2H), 7.34–7.28 (m, 5H), 7.26–7.24 (m, 3H), 5.99 (s, 1H), 5.70 (s, 1H), 2.42 (s, 3H), 2.00 (s, 3H), 1.80–1.70 (m, 10H), 1.67 (br, 2H). 13C{1H} NMR (100 MHz, CDCl3): δ 174.6, 143.9, 136.6, 134.6, 131.6, 129.4, 129.1, 128.7, 128.6, 128.1, 101.9, 84.5, 40.6, 38.7, 36.3, 27.7, 21.6. HRMS (ESI) m/z: calcd for C27H30INO4SNa+ (M + Na)+, 614.0832; found, 614.0836.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Benzoate (4ak)

Yield 85% (45.3 mg); R = 0.28 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 120.2–123.1 °C; IR (neat, cm–1): 3454, 2384, 1733, 1635, 1271, 1067, 707, 573; 1H NMR (400 MHz, CDCl3): δ 7.82 (d, J = 7.4 Hz, 2H), 7.61 (t, J = 7.2 Hz, 1H), 7.52–7.46 (m, 4H), 7.43 (d, J = 7.8 Hz, 2H), 7.40–7.36 (m, 4H), 7.03 (d, J = 7.9 Hz, 2H), 6.09 (s, 1H), 5.75 (s, 1H), 2.25 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 163.9, 143.9, 136.0, 134.7, 133.7, 131.5, 129.7, 129.3, 129.2, 128.7, 128.5, 128.0, 100.9, 85.8, 21.4. HRMS (ESI) m/z: calcd for C23H20INO4SNa+ (M + Na)+, 556.0050; found, 556.0049.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 4-Methylbenzoate (4al)

Yield 74% (40.4 mg); R = 0.29 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 141.3–142.1 °C; IR (neat, cm–1): 3460, 2382, 1635, 1272, 1067, 754, 580; 1H NMR (400 MHz, CDCl3): δ 7.71 (d, J = 7.7 Hz, 2H), 7.50 (s, 1H), 7.47 (d, J = 7.8 Hz, 2H), 7.42–7.34 (m, 5H), 7.24 (d, J = 7.5 Hz, 2H), 7.03 (d, J = 7.5 Hz, 2H), 6.08 (s, 1H), 5.73 (s, 1H), 2.44 (s, 3H), 2.26 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 164.0, 144.6, 143.8, 135.9, 134.7, 131.5, 129.7, 129.3, 129.2, 129.14, 129.1, 128.6, 127.9, 125.8, 101.0, 85.6, 21.8, 21.4. HRMS (ESI) m/z: calcd for C24H22INO4SNa+ (M + Na)+, 570.0206; found, 570.0204.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 4-Methoxybenzoate (4am)

Yield 70% (39.2 mg); R = 0.2 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 139.6–139.9 °C; IR (neat, cm–1): 3465, 2936, 2381, 1725, 1266, 1170, 1064, 744, 699; 1H NMR (400 MHz, CDCl3): δ 7.78 (d, J = 8.0 Hz, 2H), 7.48–7.46 (m, 3H), 7.38–7.35 (m, 5H), 7.04 (d, J = 7.8 Hz, 2H), 6.91 (d, J = 8.0 Hz, 2H), 6.08 (s, 1H), 5.73 (s, 1H), 3.89 (s, 3H), 2.27 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 163.9, 163.6, 143.8, 136.0, 134.7, 131.8, 131.5, 129.3, 129.1, 129.07, 128.6, 128.0, 120.9, 113.7, 101.2, 85.5, 55.5, 21.5. HRMS (ESI) m/z: calcd for C24H22INO4SNa+ (M + Na)+, 586.0161; found, 586.0170.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 4-Fluorobenzoate (4an)

Yield 68% (37.6 mg); R = 0.4 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 115.9–116.3 °C; IR (neat, cm–1): 3434, 3143, 1625, 1406, 1069, 575, 476; 1H NMR (400 MHz, CDCl3): δ 7.87 (d, J = 5.4 Hz, 1H), 7.84 (d, J = 5.4 Hz, 1H), 7.49 (s, 2H), 7.47 (s, 1H), 7.40–7.32 (m, 5H), 7.12 (t, J = 8.6 Hz, 2H), 7.06 (d, J = 8.2 Hz, 2H), 6.08 (t, J = 1.9 Hz, 1H), 5.75 (s, 1H), 2.29 (s, 3H). 13C{1H} NMR (101 MHz, CDCl3): δ 166.1 (d, J = 254.3 Hz), 163.0, 143.9, 136.0, 134.6, 132.3 (d, J = 9.4 Hz), 131.5, 129.3, 129.24, 129.2, 128.7, 128.0, 124.9 (d, J = 3.0 Hz), 115.8 (d, J = 22.0 Hz), 100.8, 85.9, 21.4. HRMS (ESI) m/z: calcd for C23H19FINO4SNa+ (M + Na)+, 573.9956; found, 573.9958.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 4-Chlorobenzoate (4ao)

Yield 65% (36.7 mg); R = 0.38 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 98.3–99.7 °C; IR (neat, cm–1): 3465, 2276, 1660, 1648, 1271, 1059, 744, 707; 1H NMR (400 MHz, CDCl3): δ 7.77 (d, J = 8.5 Hz, 2H), 7.49 (s, 2H), 7.47 (s, 1H), 7.44–7.43 (m, 1H), 7.42–7.40 (m, 1H), 7.39–7.38 (m, 1H), 7.36 (s, 1H), 7.35–7.31 (m, 3H), 7.06 (d, J = 8.2 Hz, 2H), 6.08 (s, 1H), 5.75 (s, 1H), 2.29 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 163.1, 144.0, 140.3, 136.0, 134.6, 131.5, 131.0, 129.3, 129.2, 128.9, 128.7, 128.0, 127.1, 100.7, 86.0, 21.4. HRMS (ESI) m/z: calcd for C23H19ClINO4SNa+ (M + Na)+, 589.9660; found, 589.9664.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 4-Bromobenzoate (4ap)

Yield 69% (41.9 mg); R = 0.33 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 112.1–112.8 °C; IR (neat, cm–1): 3464, 2286, 1647, 1271, 1070, 745, 706; 1H NMR (400 MHz, CDCl3): δ 7.68 (d, J = 8.4 Hz, 2H), 7.59 (d, J = 7.5 Hz, 2H), 7.49 (s, 2H), 7.47 (s, 1H), 7.42–7.31 (m, 5H), 7.06 (d, J = 7.7 Hz, 2H), 6.07 (s, 1H), 5.76 (s, 1H), 2.29 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 163.3, 144.0, 135.9, 134.5, 131.9, 131.4, 131.1, 129.3, 129.27, 129.25, 128.9, 128.7, 127.9, 127.5, 100.6, 86.0, 21.5. HRMS (ESI) m/z: calcd for C23H19BrINO4SNa+ (M + Na)+, 633.9155; found, 633.9157.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 2-Methylbenzoate (4aq)

Yield 68% (37.0 mg); R = 0.38 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 96.6–96.9 °C; IR (neat, cm–1): 3456, 2935, 2383, 1635, 1049, 754, 702; 1H NMR (400 MHz, CDCl3): δ 7.51 (d, J = 7.8 Hz, 2H), 7.47–7.43 (m, 3H), 7.40–7.33 (m, 5H), 7.29 (d, J = 7.2 Hz, 1H), 7.18 (t, J = 7.2 Hz, 1H), 7.09 (d, J = 7.5 Hz, 2H), 6.11 (s, 1H), 5.75 (s, 1H), 2.63 (s, 3H), 2.30 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 164.3, 143.9, 141.6, 136.1, 134.7, 132.7, 132.0, 131.5, 130.1, 129.3, 129.1, 129.09, 128.6, 127.9, 127.5, 125.6, 101.3, 85.6, 21.8, 21.5. HRMS (ESI) m/z: calcd for C24H22INO4SNa+ (M + Na)+, 570.0206; found, 570.0205.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 3-Fluorobenzoate (4ar)

Yield 68% (37.4 mg); R = 0.31 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 92.1–92.7 °C; IR (neat, cm–1): 3453, 2928, 2375, 1633, 1081, 756; 1H NMR (400 MHz, CDCl3): δ 7.66 (d, J = 7.7 Hz, 1H), 7.49 (s, 2H), 7.47 (s, 1H), 7.44–7.39 (m, 4H), 7.37–7.30 (m, 5H), 7.07 (d, J = 7.9 Hz, 2H), 6.07 (s, 1H), 5.76 (s, 1H), 2.29 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 162.9, 162.8, 162.4 (d, J = 246.5 Hz), 144.1, 135.9, 134.5, 131.5, 130.3, 130.2, 129.4, 129.3 (d, J = 2.4 Hz), 128.7, 127.9, 125.5 (d, J = 3.1 Hz), 120.8 (d, J = 21.2 Hz), 116.4 (d, J = 23.1 Hz), 100.5, 86.2, 21.4. HRMS (ESI) m/z: calcd for C23H19FINO4SNa+ (M + Na)+, 573.9956; found, 573.9959.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 2-Naphthoate (4as)

Yield 72% (41.4 mg); R = 0.24 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 121.8–122.3 °C; IR (neat, cm–1): 3452, 2928, 2366, 1634, 1025, 724, 668; 1H NMR (400 MHz, CDCl3): δ 8.30 (s, 1H), 7.91–7.86 (m, 3H), 7.82 (d, J = 8.5 Hz, 1H), 7.64 (t, J = 7.3 Hz, 1H), 7.59 (d, J = 7.5 Hz, 1H), 7.56 (s, 1H), 7.48 (d, J = 8.0 Hz, 2H), 7.44–7.38 (m, 5H), 6.97 (d, J = 7.9 Hz, 2H), 6.14 (s, 1H), 5.76 (s, 1H), 2.08 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 164.1, 143.9, 136.0, 135.7, 134.7, 132.2, 131.5, 131.46, 129.32, 129.3, 129.2, 129.2, 128.8, 128.7, 128.3, 127.9, 127.8, 126.9, 125.8, 124.9, 100.9, 86.0, 21.3. HRMS (ESI) m/z: calcd for C27H22INO4SNa+ (M + Na)+, 606.0206; found, 606.0207.

2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl Cinnamate (4at)

Yield 69% (38.5 mg); R = 0.36 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 134.0–135.2 °C; IR (neat, cm–1): 3462, 2936, 2382, 1758, 1634, 1366, 1215, 1013, 716; 1H NMR (400 MHz, CDCl3): δ 7.56 (d, J = 16.0 Hz, 1H), 7.51–7.49 (m, 4H), 7.43–7.41 (m, 3H), 7.38–7.36 (m, 2H), 7.35–7.31 (m, 4H), 7.15 (d, J = 7.9 Hz, 2H), 6.25 (d, J = 16.0 Hz, 1H), 6.08 (s, 1H), 5.73 (s, 1H), 2.27 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 164.1, 146.6, 143.9, 136.0, 134.6, 133.7, 131.5, 130.9, 129.3, 129.1, 129.0, 128.6, 128.2, 128.1, 116.2, 101.0, 85.3, 21.4. HRMS (ESI) m/z: calcd for C25H22INO4SNa+ (M + Na)+, 582.0206; found, 582.0208.

2-Iodo-1-(4-methyl-N-(p-tolyl)phenylsulfonamido)allyl Acetate (4ba)

Yield 89% (43.0 mg); R = 0.28 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 112.3–113.4 °C; IR (neat, cm–1): 3463, 2934, 2382, 1755, 1635, 1217, 1087, 744; 1H NMR (400 MHz, CDCl3): δ 7.53 (d, J = 7.7 Hz, 2H), 7.26 (s, 2H), 7.24 (s, 1H), 7.10 (br, 4H), 6.03 (s, 1H), 5.72 (s, 1H), 2.44 (s, 3H), 2.35 (s, 3H), 1.98 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 143.9, 139.2, 136.1, 131.7, 131.1, 129.2, 128.8, 128.1, 101.3, 84.9, 21.6, 21.2, 20.5. HRMS (ESI) m/z: calcd for C19H20INO4SNa+ (M + Na)+, 508.0050; found, 508.0048.

2-Iodo-1-(N-(4-methoxyphenyl)-4-methylphenylsulfonamido)allyl Acetate (4ca)

Yield 81% (40.6 mg); R = 0.2 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 142.1–142.3 °C; IR (neat, cm–1): 3469, 2384, 1634, 1270, 1072, 749; 1H NMR (400 MHz, CDCl3): δ 7.53 (d, J = 5.2 Hz, 2H), 7.25 (d, J = 7.2 Hz, 4H), 7.14 (d, J = 6.3 Hz, 1H), 6.80 (d, J = 7.2 Hz, 2H), 6.03 (s, 1H), 5.74 (s, 1H), 3.81 (s, 3H), 2.44 (s, 3H), 1.99 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 159.9, 143.9, 136.1, 132.7, 129.3, 128.8, 128.1, 126.9, 113.7, 101.5, 85.0, 55.3, 21.6, 20.6. HRMS (ESI) m/z: calcd for C19H20INO5SNa+ (M + Na)+, 523.9999; found, 523.9996.

1-(N-(4-Fluorophenyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4da)

Yield 66% (32.4 mg); R = 0.22 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 108.2–109.4 °C; IR (neat, cm–1): 3468, 2965, 2376, 1660, 1213, 1011, 740; 1H NMR (400 MHz, CDCl3): δ 7.52 (d, J = 8.1 Hz, 2H), 7.27 (d, J = 2.8 Hz, 2H), 7.26–7.22 (m, 3H), 7.21 (d, J = 5.0 Hz, 1H), 6.99 (t, J = 8.5 Hz, 2H), 6.04 (s, 1H), 5.75 (s, 1H), 2.44 (s, 3H), 2.00 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.0, 162.7 (d, J = 248.3 Hz), 144.3, 135.8, 133.3 (d, J = 8.8 Hz), 130.3 (d, J = 3.2 Hz), 129.4, 129.0, 128.0, 115.6 (d, J = 22.5 Hz), 101.1, 84.8, 21.6, 20.5. HRMS (ESI) m/z: calcd for C18H17FINO4SNa+ (M + Na)+, 511.9799; found, 511.9798.

1-(N-(4-Chlorophenyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4ea)

Yield 73% (36.9 mg); R = 0.24 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 129.3–130.7 °C; IR (neat, cm–1): 3448, 2932, 2378, 1643, 1273, 1014, 752; 1H NMR (400 MHz, CDCl3): δ 7.44 (d, J = 8.0 Hz, 2H), 7.22–7.16 (m, 5H), 7.11 (d, J = 8.5 Hz, 2H), 5.98 (s, 1H), 5.67 (s, 1H), 2.37 (s, 3H), 1.91 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 167.9, 144.3, 135.7, 135.2, 133.0, 132.6, 129.4, 129.1, 128.8, 128.0, 100.9, 84.8, 21.6, 20.5. HRMS (ESI) m/z: calcd for C18H17ClINO4SNa+ (M + Na)+, 527.9503; found, 527.9506.

1-(N-(4-Bromophenyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4fa)

Yield 71% (39.0 mg); R = 0.28 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 145.6–145.9 °C; IR (neat, cm–1): 3475, 1936, 2368, 1758, 1636, 1216, 1013, 753; 1H NMR (400 MHz, CDCl3): δ 7.52 (d, J = 8.2 Hz, 2H), 7.43 (d, J = 8.5 Hz, 2H), 7.27 (d, J = 3.0 Hz, 1H), 7.25 (d, J = 8.3 Hz, 2H), 7.12 (d, J = 8.5 Hz, 2H), 6.05 (s, 1H), 5.75 (s, 1H), 2.44 (s, 3H), 1.99 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 167.9, 144.3, 135.7, 133.6, 133.0, 131.9, 129.4, 129.2, 128.0, 123.5, 100.9, 84.7, 21.6, 20.5. HRMS (ESI) m/z: calcd for C18H17BrINO4SNa+ (M + Na)+, 571.8999; found, 571.8998.

2-Iodo-1-(N-(3-methoxyphenyl)-4-methylphenylsulfonamido)allyl Acetate (4ga)

Yield 72% (36.0 mg); R = 0.2 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 114.8–115.9 °C; IR (neat, cm–1): 3458, 2935, 2388, 1617, 1172, 1087, 752, 569; 1H NMR (400 MHz, CDCl3): δ 7.55 (d, J = 5.4 Hz, 2H), 7.29–7.17 (m, 4H), 6.91 (d, J = 5.7 Hz, 1H), 6.83 (s, 2H), 6.05 (s, 1H), 5.73 (s, 1H), 3.76 (s, 3H), 2.44 (s, 3H), 1.98 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 159.3, 144.1, 136.0, 135.5, 129.3, 128.9, 128.1, 123.5, 117.3, 114.8, 100.9, 84.9, 55.3, 21.6, 20.5. HRMS (ESI) m/z: calcd for C19H20INO5SNa+ (M + Na)+, 523.9999; found, 523.9998.

1-(N-(3-Bromophenyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4ha)

Yield 62% (34.1 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 144.9–145.7 °C; IR (neat, cm–1): 3466, 2377, 4642, 1272, 745; 1H NMR (400 MHz, CDCl3): δ 7.54 (d, J = 8.2 Hz, 2H), 7.50 (d, J = 8.1 Hz, 1H), 7.39 (s, 1H), 7.29 (d, J = 8.0 Hz, 2H), 7.24–7.16 (m, 3H), 6.08 (s, 1H), 5.77 (s, 1H), 2.45 (s, 3H), 2.00 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 167.9, 144.4, 135.8, 135.6, 134.4, 132.3, 130.1, 129.7, 129.4, 129.2, 128.0, 121.6, 100.7, 84.7, 21.6, 20.5. HRMS (ESI) m/z: calcd for C18H17BrINO4SNa+ (M + Na)+, 571.8998; found, 571.9004.

1-(N-(3,5-Dimethoxyphenyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4ia)

Yield 72% (38.3 mg); R = 0.10 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 81.5–82.3 °C; IR (neat, cm–1): 3457, 2968, 2834, 1629, 1438, 1168, 1085, 772; 1H NMR (400 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 2H), 7.28 (d, J = 5.5 Hz, 2H), 7.21 (s, 1H), 6.46 (s, 1H), 6.42 (s, 2H), 6.08 (s, 1H), 5.76 (s, 1H), 3.73 (s, 6H), 2.44 (s, 3H), 1.96 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 160.0, 144.1, 136.1, 136.0, 129.3, 129.1, 128.1, 109.8, 101.1, 100.8, 84.9, 55.4, 21.6, 20.5. HRMS (ESI) m/z: calcd for C20H22INO6SNa+ (M + Na)+, 554.0105; found, 554.0108.

2-Iodo-1-(4-methyl-N-(naphthalen-2-yl)phenylsulfonamido)allyl Acetate (4ja)

Yield 78% (40.5 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 123.3–125.2 °C; IR (neat, cm–1): 3456, 2924, 2384, 1643, 1272, 1084, 752; 1H NMR (400 MHz, CDCl3): δ 7.85 (d, J = 7.3 Hz, 1H), 7.80 (d, J = 7.5 Hz, 1H), 7.76 (d, J = 9.9 Hz, 2H), 7.54–7.49 (m, 4H), 7.34 (br, 2H), 7.25 (d, J = 8.2 Hz, 2H), 6.03 (s, 1H), 5.66 (s, 1H), 2.45 (s, 3H), 2.04 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 144.1, 136.1, 133.1, 132.9, 131.9, 130.8, 129.3, 129.0, 128.6, 128.4, 128.3, 128.1, 127.6, 127.1, 126.3, 101.0, 85.2, 21.6, 20.7. HRMS (ESI) m/z: calcd for C22H20INO4SNa+ (M + Na)+, 544.0050; found, 544.0046.

1-(N-Benzyl-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4ka)

Yield 69% (33.4 mg); R = 0.24 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 86.9–88.9 °C; IR (neat, cm–1): 3463, 2968, 2374, 1662, 1164, 1056, 738; 1H NMR (400 MHz, CDCl3): δ 7.61 (d, J = 8.2 Hz, 2H), 7.34–7.31 (m, 2H), 7.24–7.22 (m, 5H), 6.90 (s, 1H), 6.37 (s, 1H), 5.98 (s, 1H), 4.51 (d, J = 15.9 Hz, 1H), 4.40 (d, J = 15.9 Hz, 1H), 2.41 (s, 3H), 1.84 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 143.8, 136.5, 136.3, 129.4, 129.2, 128.9, 128.0, 127.8, 127.4, 102.5, 84.7, 48.0, 21.5, 20.3. HRMS (ESI) m/z: calcd for C19H20INO4SNa+ (M + Na)+, 508.0050; found, 508.0052.

1-(N-Benzyl-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4la)

Yield 91% (45.6 mg); R = 0.35 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 109.9–110.5 °C; IR (neat, cm–1): 3439, 2965, 2385, 1756, 1634, 1165, 1101, 744; 1H NMR (400 MHz, CDCl3): δ 7.61 (d, J = 8.0 Hz, 2H), 7.25–7.18 (m, 4H), 7.05 (d, J = 7.5 Hz, 2H), 6.89 (s, 1H), 6.38 (s, 1H), 5.98 (s, 1H), 4.46 (d, J = 15.8 Hz, 1H), 4.35 (d, J = 15.9 Hz, 1H), 2.41 (s, 3H), 2.32 (s, 3H), 1.85 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 143.7, 137.0, 136.5, 133.1, 129.4, 129.2, 128.9, 128.6, 127.8, 102.6, 84.7, 47.8, 21.5, 21.1, 20.3. HRMS (ESI) m/z: calcd for C20H22INO4SNa+ (M + Na)+, 522.0206; found, 522.0208.

2-Iodo-1-(N-(4-methoxybenzyl)-4-methylphenylsulfonamido)allyl Acetate (4ma)

Yield 67% (35.0 mg); R = 0.16 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 114.2–116.2 °C; IR (neat, cm–1): 3469, 2939, 2383, 1629, 1166, 1028, 756, 669; 1H NMR (400 MHz, CDCl3): δ 7.52 (d, J = 7.9 Hz, 2H), 7.18 (d, J = 4.4 Hz, 1H), 7.15 (d, J = 7.3 Hz, 3H), 6.81 (s, 1H), 6.69 (d, J = 8.2 Hz, 2H), 6.30 (s, 1H), 5.91 (s, 1H), 4.36 (d, J = 15.6 Hz, 1H), 4.27 (d, J = 15.7 Hz, 1H), 3.72 (s, 3H), 2.33 (s, 3H), 1.79 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 159.0, 143.7, 136.6, 130.4, 129.3, 129.1, 128.2, 127.7, 113.3, 102.7, 84.7, 55.2, 47.5, 21.5, 20.3. HRMS (ESI) m/z: calcd for C20H22INO5SNa+ (M + Na)+, 538.0156; found, 538.0159.

1-(N-(4-Fluorobenzyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4na)

Yield 68% (34.2 mg); R = 0.18 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 58.4–59.6 °C; IR (neat, cm–1): 3458, 2382, 1635, 1273, 1056, 752; 1H NMR (400 MHz, CDCl3): δ 7.61 (d, J = 8.1 Hz, 2H), 7.34–7.30 (m, 2H), 7.26 (s, 1H), 7.24 (s, 1H), 6.93 (t, J = 8.6 Hz, 2H), 6.88 (s, 1H), 6.37 (s, 1H), 5.97 (s, 1H), 4.44 (d, J = 15.9 Hz, 1H), 4.38 (d, J = 15.9 Hz, 1H), 2.41 (s, 3H), 1.85 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 167.9, 162.1 (d, J = 244.6 Hz), 143.9, 136.3, 132.0 (d, J = 3.2 Hz), 131.0, 130.7, 129.4, 129.2, 127.6 (d, J = 12.5 Hz), 114.9, 114.7, 102.5, 84.6, 47.2, 21.5, 20.2. HRMS (ESI) m/z: calcd for C19H19FINO4SNa+ (M + Na)+, 525.9956; found, 525.9959.

1-(N-(4-Chlorobenzyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4oa)

Yield 62% (32 mg); R = 0.28 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 135.6–136.2 °C; IR (neat, cm–1): 3458, 2937, 2383, 1653, 1363, 1166, 1061, 1016, 822, 745; 1H NMR (400 MHz, CDCl3): δ 7.53 (d, J = 8.0 Hz, 2H), 7.29 (d, J = 8.1 Hz, 2H), 7.19–7.13 (m, 4H), 6.82 (s, 1H), 6.30 (s, 1H), 5.91 (s, 1H), 4.35 (d, J = 16.0 Hz, 1H), 4.27 (d, J = 16.0 Hz, 1H), 2.35 (s, 3H), 1.79 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 167.9, 144.1, 136.2, 135.4, 131.0, 130.6, 129.5, 129.3, 127.7, 121.4, 102.3, 84.7, 47.3, 21.5, 20.3. HRMS (ESI) m/z: calcd for C19H19ClINO4SNa+ (M + Na)+, 541.9660; found, 541.9660.

1-(N-(4-Bromobenzyl)-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4pa)

Yield 84% (47.1 mg); R = 0.21 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 112.7–114.6 °C; IR (neat, cm–1): 3457, 2936, 2835, 1758, 1361, 1165, 745, 699; 1H NMR (400 MHz, CDCl3): δ 7.61 (d, J = 8.0 Hz, 2H), 7.37 (d, J = 8.1 Hz, 2H), 7.26–7.20 (m, 4H), 6.89 (s, 1H), 6.38 (s, 1H), 5.98 (s, 1H), 4.43 (d, J = 16.0 Hz, 1H), 4.35 (d, J = 16.1 Hz, 1H), 2.43 (s, 3H), 1.87 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 167.9, 144.1, 136.2, 135.4, 131.1, 130.6, 129.5, 129.3, 127.7, 121.4, 102.4, 84.7, 47.3, 21.5, 20.3. HRMS (ESI) m/z: calcd for C19H19BrINO4SNa+ (M + Na)+, 581.9135; found, 581.9145.

2-Iodo-1-(4-methyl-N-phenethylphenylsulfonamido)allyl Acetate (4qa)

Yield 72% (36.1 mg); R = 0.35 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 81.5–82.4 °C; IR (neat, cm–1): 3457, 2383, 1755, 1635, 1272, 1166, 756; 1H NMR (400 MHz, CDCl3): δ 7.76 (d, J = 7.6 Hz, 2H), 7.29 (t, J = 7.1 Hz, 4H), 7.23 (d, J = 6.9 Hz, 1H), 7.16 (d, J = 7.4 Hz, 2H), 6.87 (s, 1H), 6.51 (s, 1H), 6.14 (s, 1H), 3.43–3.29 (m, 2H), 3.07–2.96 (m, 2H), 2.42 (s, 3H), 1.91 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.1, 144.0, 138.7, 136.2, 129.6, 128.7, 128.69, 128.6, 127.7, 126.5, 102.9, 84.7, 46.2, 37.3, 21.5, 20.4. HRMS (ESI) m/z: calcd for C20H22INO4SNa+ (M + Na)+, 522.0206; found, 522.0208.

1-(N-Butyl-4-methylphenylsulfonamido)-2-iodoallyl Acetate (4ra)

Yield 48% (21.7 mg); R = 0.28 (SiO2; hexanes/ethyl acetate, 10:1); yellow liquid; IR (neat, cm–1): 3466, 2991, 2389, 1644, 1164, 752; 1H NMR (400 MHz, CDCl3): δ 7.66 (d, J = 7.9 Hz, 2H), 7.23 (d, J = 7.9 Hz, 2H), 6.75 (s, 1H), 6.37 (s, 1H), 5.98 (s, 1H), 3.18–3.11 (m, 1H), 3.06–2.98 (m, 1H), 2.36 (s, 3H), 1.85 (s, 3H), 1.64–1.52 (m, 2H), 1.24–1.14 (m, 2H), 0.82 (t, J = 7.3 Hz, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.2, 143.8, 136.4, 129.5, 128.5, 127.7, 102.8, 84.7, 44.4, 32.5, 21.5, 20.4, 20.2, 13.6. HRMS (ESI) m/z: calcd for C16H22INO4SNa+ (M + Na)+, 474.0206; found, 474.0207.

2-Iodo-1-(N-phenylmethylsulfonamido)allyl Acetate (4sa)

Yield 74% (29.3 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 113.1–114.4 °C; IR (neat, cm–1): 3760, 3448, 2939, 2384, 1756, 1653, 1216, 1020, 746, 701; 1H NMR (400 MHz, CDCl3): δ 7.51–7.47 (m, 2H), 7.42–7.40 (m, 3H), 7.12 (s, 1H), 6.14 (s, 1H), 5.80 (s, 1H), 3.04 (s, 3H), 2.23 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.2, 134.2, 131.2, 129.5, 129.2, 129.0, 101.2, 85.1, 39.9, 20.8. HRMS (ESI) m/z: calcd for C12H14INO4Na+ (M + Na)+, 417.9580; found, 417.9592.

2-Iodo-1-(N-phenylacetamido)allyl Acetate (4ta)

Yield 81% (29.0 mg); R = 0.13 (SiO2; hexanes/ethyl acetate, 10:1); brown liquid; IR (neat, cm–1): 3460, 2934, 2380, 1687, 1272, 1219, 1096, 1014, 823, 705; 1H NMR (400 MHz, CDCl3): δ 7.64 (s, 1H), 7.41 (s, 3H), 7.33 (s, 2H), 6.13 (s, 1H), 5.81 (s, 1H), 2.15 (s, 3H), 1.88 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 171.2, 168.1, 137.6, 129.9, 129.1, 128.9, 128.4, 102.4, 80.3, 23.2, 20.7. HRMS (ESI) m/z: calcd for C13H14INO3Na+ (M + Na)+, 381.9911; found, 381.9914.

2-Iodo-1-(2-oxooxazolidin-3-yl)allyl Acetate (4ua)

Yield 48% (15.1 mg); R = 0.1 (SiO2; hexanes/ethyl acetate, 10:1); colorless liquid; IR (neat, cm–1): 2354, 2934, 2384, 1751, 1652, 1422, 1258, 1038, 927, 757; 1H NMR (400 MHz, CDCl3): δ 6.76 (s, 1H), 6.55 (s, 1H), 6.12 (s, 1H), 4.41 (t, J = 7.7 Hz, 2H), 3.60 (t, J = 7.8 Hz, 2H), 2.16 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 168.0, 156.8, 128.7, 101.3, 80.6, 62.5, 39.9, 20.5. HRMS (ESI) m/z: calcd for C8H10INO4Na+ (M + Na)+, 333.9547; found, 333.9542.

(Z)-2-Iodo-3-(N-mesityl-4-methylphenylsulfonamido)allyl Acetate (5)

Yield 56% (28.6 mg); R = 0.26 (SiO2; hexanes/ethyl acetate, 10:1); white solid; mp 132.9–133.6 °C; IR (neat, cm–1): 3454, 2937, 2382, 1625, 1088, 757; 1H NMR (400 MHz, CDCl3): δ 7.60 (d, J = 8.0 Hz, 2H), 7.56 (s, 1H), 7.31 (d, J = 7.9 Hz, 2H), 6.84 (s, 2H), 4.83 (s, 2H), 2.45 (s, 3H), 2.29 (s, 3H), 2.07 (s, 3H), 1.82 (s, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 170.5, 144.6, 140.3, 139.6, 135.9, 133.0, 129.9, 129.5, 129.2, 128.9, 127.9, 73.6, 67.9, 21.6, 21.1, 21.0, 19.1. HRMS (ESI) m/z: calcd for C21H24INO4SNa+ (M + Na)+, 536.0363; found, 536.0366.

(2S)-2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 2-((tert-Butoxycarbonyl)amino)-3-phenylpropanoate (6, dr = 1:1)

Yield 51% (34.4 mg); R = 0.2 (SiO2; hexanes/ethyl acetate, 10:1); colorless liquid; IR (neat, cm–1): 3438, 2991, 1718, 1500, 1368, 1169, 1084, 703, 666; 1H NMR (400 MHz, CDCl3): δ 7.57 (d, J = 7.6 Hz, 2H), 7.43 (d, J = 7.6 Hz, 2H), 7.34–7.26 (m, 12H), 7.23 (d, J = 5.1 Hz, 6H), 7.15 (t, J = 7.3 Hz, 6H), 5.99 (s, 1H), 5.85 (s, 1H), 5.67 (s, 1H), 5.65 (s, 1H), 5.30 (s, 2H), 4.85 (d, J = 7.9 Hz, 1H), 4.76 (d, J = 7.9 Hz, 1H), 4.49 (s, 2H), 3.14–3.05 (m, 2H), 3.04–2.96 (m, 2H), 2.41 (s, 3H), 2.39 (s, 3H), 1.43 (s, 9H), 1.36 (s, 9H). 13C{1H} NMR (100 MHz, CDCl3): δ 169.9, 169.7, 154.9, 144.3, 144.2, 136.0, 135.8, 135.7, 135.6, 134.2, 131.5, 131.48, 129.9, 129.8, 129.5, 129.43, 129.4, 129.3, 129.2, 129.1, 128.8, 128.7, 128.69, 128.6, 128.2, 128.1, 127.2, 127.1, 99.9, 99.8, 86.1, 86.0, 80.2, 60.4, 54.2, 53.9, 53.5, 37.8, 37.6, 28.3, 28.2, 21.7, 21.6, 14.2. HRMS (ESI) m/z: calcd for C30H33IN2O6SNa+ (M + Na)+, 699.0996; found, 699.1002.

(2S)-2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 2-Acetamido-3-phenylpropanoate (7, dr = 1:1)

Yield 47% (28.8 mg); R = 0.25 (SiO2; hexanes/ethyl acetate, 3:1); yellow liquid; IR (neat, cm–1): 3403, 3303, 3075, 1760, 1688, 1500, 1082, 714, 703; 1H NMR (400 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 2H), 7.41 (d, J = 7.8 Hz, 2H), 7.37–7.30 (m, 4H), 7.30–7.22 (m, 12H), 7.17 (t, J = 7.5 Hz, 4H), 7.14–7.07 (m, 4H), 6.08–6.00 (m, 3H), 5.77 (s, 1H), 5.68 (s, 1H), 5.62 (s, 1H), 5.27 (s, 1H), 4.79 (dt, J = 14.4, 7.2 Hz, 2H), 3.13 (dd, J = 14.2, 5.2 Hz, 1H), 3.05 (d, J = 6.3 Hz, 2H), 3.02–2.97 (m, 1H), 2.40 (s, 3H), 2.37 (s, 3H), 1.95 (s, 3H), 1.88 (s, 3H). 13C{1H} NMR (100 MHz, CDCl3): δ 170.1, 169.9, 169.7, 169.6, 144.4, 144.3, 135.9, 135.6, 135.5, 135.4, 134.1, 133.99, 131.6, 131.4, 130.0, 129.5, 129.4, 129.3, 129.29, 129.25, 129.2, 128.84, 128.8, 128.7, 128.6, 128.2, 128.1, 127.32, 127.3, 99.8, 99.5, 86.3, 86.2, 62.8, 52.9, 52.6, 37.4, 37.2, 22.9, 22.8, 21.7. HRMS (ESI) m/z: calcd for C27H27IN2O5SNa+ (M + Na)+, 641.0578; found, 641.0575.

(2S)-2-Iodo-1-(4-methyl-N-phenylphenylsulfonamido)allyl 2-((tert-Butoxycarbonyl)amino)-3-(4-hydroxyphenyl)propanoate (8, dr = 1:1)

Yield 51% (35.4 mg); R = 0.2 (SiO2; hexanes/ethyl acetate, 3:1); colorless liquid; IR (neat, cm–1): 3402, 2991, 1700, 1520, 1168, 1068, 736, 701; 1H NMR (400 MHz, CDCl3): δ 7.56 (d, J = 7.8 Hz, 2H), 7.43 (d, J = 7.7 Hz, 2H), 7.33–7.30 (m, 3H), 7.26 (d, J = 7.5 Hz, 4H), 7.23–7.11 (m, 8H), 7.05 (d, J = 7.8 Hz, 2H), 6.98 (d, J = 7.8 Hz, 2H), 6.79–6.70 (m, 4H), 6.02 (br, 1H), 5.99 (s, 1H), 5.87 (s, 1H), 5.65 (s, 2H), 4.91–4.84 (m, 2H), 4.46–4.41 (m, 2H), 3.03–2.96 (m, 2H), 2.94–2.88 (m, 2H), 2.39 (s, 3H), 2.37 (s, 3H), 1.41 (s, 9H), 1.35 (s, 9H). 13C{1H} NMR (100 MHz, CDCl3): δ 170.0, 169.8, 155.1, 144.3, 144.28, 135.9, 135.8, 134.1, 131.6, 131.5, 130.5, 130.4, 130.0, 129.9, 129.6, 129.5, 129.4, 129.3, 129.2, 128.7, 128.6, 128.2, 128.1, 127.9, 127.8, 127.3, 127.23, 127.2, 121.7, 115.7, 99.9, 99.8, 86.1, 80.3, 60.5, 54.4, 54.2, 37.1, 36.8, 28.3, 28.2, 21.6, 21.58, 14.1. HRMS (ESI) m/z: calcd for C30H33IN2O7SNa+ (M + Na)+, 715.0945; found, 715.0949.