Literature DB >> 25484669

Crystal structure of 1-(2-chloro-acet-yl)-2,6-bis-(4-fluoro-phen-yl)-3,3-di-methyl-piperidin-4-one.

S Jothivel1, Jibon Kotoky2, S Kabilan1.   

Abstract

In the title mol-ecule, C21H20ClF2NO2, the piperidine ring adopts a slightly distorted boat conformation. The two benzene rings form a dihedral angle of 87.43 (1)°. A weak intra-molecular C-H⋯π inter-action is observed. In the crystal, weak C-H⋯O hydrogen bonds and weak C-H⋯π inter-actions connect the mol-ecules, forming a three-dimensional network.

Entities:  

Keywords:  Piperidone; crystal structure; weak hydrogen bonds

Year:  2014        PMID: 25484669      PMCID: PMC4257194          DOI: 10.1107/S1600536814021278

Source DB:  PubMed          Journal:  Acta Crystallogr Sect E Struct Rep Online        ISSN: 1600-5368


Chemical context

Piperidones are an important group of heterocyclic compounds in the field of medicinal chemistry due to their biological activities, which include cytotoxic properties (Dimmock et al., 2001 ▶). They are also reported to possess analgesic, anti-inflammatory, central nervous system (CNS), local anaesthetic, anti­cancer and anti­microbial activities (Perumal et al., 2001 ▶). The present investigation was undertaken to establish the mol­ecular structure, the conformation of the heterocyclic ring and the orientation of the 4-fluoro­phenyl groups with respect to each other.

Structural commentary

The mol­ecular structure of the title compound is shown in Fig. 1 ▶. The sum of the bond angles around atom N1 (359.6°) confirms sp 2 hybridization. The N1—C14 [1.356 (2) Å] and C14—O1 [1.221 (2) Å] bond distances indicate the presence electron delocalization in this part of the mol­ecule. The six-membered piperidine ring adopts a slightly distorted boat conformation. The benzene rings form a dihedral angle of 87.43 (1)°. The equatorial and axial orientation of the methyl substituents bonded to atom C2 are described by the N1—C1—C2—C6 and N1—C1—C2—C7 torsion angles of −117.45 (16)° and −57.2 (2)°, respectively. A weak intra­molecular C—H⋯π inter­action is observed, which involves the C8–C13 benzene ring (see Table 1 ▶).
Figure 1

The mol­ecular structure of the title compound, showing 30% probability displacement ellipsoids.

Table 1

Hydrogen-bond geometry (Å, °)

Cg1 and Cg2 are the centroids of the C16–C21 and C8–C13 rings, respectively.

D—H⋯A D—HH⋯A DA D—H⋯A
C5—H5⋯O1i 0.982.503.453 (2)165
C15—H15A⋯O1i 0.972.463.429 (3)174
C20—H20⋯O2ii 0.932.453.298 (3)151
C10—H10⋯Cg1iii 0.932.663.499 (2)151
C17—H17⋯Cg20.932.853.771 (2)170

Symmetry codes: (i) ; (ii) ; (iii) .

Supra­molecular features

In the crystal, weak C—H⋯O hydrogen bonds and weak C—H⋯π inter­actions link mol­ecules, forming a three-dimensional network (Fig. 2 ▶). Atom O1 acts an acceptor for two weak C—H⋯O hydrogen bonds forming an (7) ring.
Figure 2

Part of the crystal structure showing weak hydrogen bonds as dashed lines. H atoms not involved in the hydrogen bonds or weak C—H⋯π stacking inter­actions are not shown.

Database survey

A search of the Cambridge Structural Database (Version 5.35, updates to May 2014; Allen, 2002 ▶) revealed four closely related structures in which the dihedral angles between the benzene rings (which are given in square brackets) can be compared to the title compound. These structures are r-2,c-6-bis­(4-fluoro­phen­yl)-t-3,t-5-di­methyl­piperidin-4-one [50.4 (1)°] (Gayathri et al., 2008a ▶), r-2,c-6-bis­(4-chloro­phen­yl)-c-3,t-3-di­methyl­piperidin-4-one [77.23 (7)°] (Llango et al., 2008 ▶), r-2,c-6-bis­(4-chloro­phen­yl)-t-3-isopropyl-1-nitro­sopiperidin-4-one [21.56°] (Gayathri et al., 2008b ▶) and r-2,c-6-bis­(4-chloro­phen­yl)-t-3-iso­propyl­piperidin-4-one [52.4 (1)°] (Thiruval­luvar et al., 2007 ▶).

Synthesis and crystallization

The synthesis followed the procedure of Aridoss et al. (2007 ▶). To a stirred solution of 3,3-dimethyl-2,6-bis­(p-fluoro­phen­yl) piperidin-4-one (1.4 g, 5 mmol), and tri­ethyl­amine (2 ml, 14.4 mmol) in benzene (20 ml), di­chloro­acetyl­chloride (1 ml, 10 mmol) in benzene (20 ml) was added dropwise for about half an hour. Stirring was continued with mild heating using a magnetic stirrer for 7 h. The progress of the reaction was monitored by TLC. After the completion of reaction, it was poured into water and extracted with ether. The collected ether extracts were then washed well with 3% sodium bicarbonate solution and dried over anhydrous Na2SO4. The pasty mass obtained was purified by crystallization from a benzenepetroleum ether solution (333–353 K) in the ratio of 95:5. X-ray quality crystals were grown by slow evaporation of an ethanol solution of the title compound at ambient temperature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▶. All H atoms were placed in calculated positions (C—H = 0.93–0.97 Å) and included in the refinement in a riding-model approximation with U iso(H) = 1.2U eq(C) or 1.5U eq(Cmeth­yl).
Table 2

Experimental details

Crystal data
Chemical formulaC21H20ClF2NO2
M r 391.83
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)13.5270 (3), 10.0150 (2), 15.2560 (3)
β (°)113.803 (1)
V3)1890.97 (7)
Z 4
Radiation typeMo Kα
μ (mm−1)0.24
Crystal size (mm)0.35 × 0.30 × 0.30
 
Data collection
DiffractometerBruker APEXII CCD
Absorption correctionMulti-scan (SADABS; Bruker, 2004)
T min, T max 0.914, 0.944
No. of measured, independent and observed [I > 2σ(I)] reflections17109, 3327, 2643
R int 0.030
(sin θ/λ)max−1)0.595
 
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S 0.038, 0.097, 1.02
No. of reflections3327
No. of parameters245
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.34, −0.42

Computer programs: APEX2 and SAINT (Bruker, 2004 ▶), SIR92 (Altomare et al., 1993 ▶), SHELXL97 (Sheldrick, 2008 ▶), ORTEP-3 for Windows (Farrugia, 2012 ▶) and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536814021278/lh5727sup1.cif Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814021278/lh5727Isup2.hkl Click here for additional data file. Supporting information file. DOI: 10.1107/S1600536814021278/lh5727Isup3.tif Click here for additional data file. Supporting information file. DOI: 10.1107/S1600536814021278/lh5727Isup4.cml CCDC reference: 1026047 Additional supporting information: crystallographic information; 3D view; checkCIF report
C21H20ClF2NO2F(000) = 816
Mr = 391.83Dx = 1.376 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 6438 reflections
a = 13.5270 (3) Åθ = 2.6–27.4°
b = 10.0150 (2) ŵ = 0.24 mm1
c = 15.2560 (3) ÅT = 293 K
β = 113.803 (1)°Block, colourless
V = 1890.97 (7) Å30.35 × 0.30 × 0.30 mm
Z = 4
Bruker APEXII CCD diffractometer3327 independent reflections
Radiation source: fine-focus sealed tube2643 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
ω and φ scansθmax = 25.0°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2004)h = −15→16
Tmin = 0.914, Tmax = 0.944k = −11→11
17109 measured reflectionsl = −18→18
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.038H-atom parameters constrained
wR(F2) = 0.097w = 1/[σ2(Fo2) + (0.0329P)2 + 1.0437P] where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
3327 reflectionsΔρmax = 0.34 e Å3
245 parametersΔρmin = −0.42 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0104 (10)
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.
xyzUiso*/Ueq
C10.78563 (14)−0.24331 (17)0.58593 (12)0.0380 (4)
H10.7638−0.32110.61290.046*
C20.68341 (15)−0.1993 (2)0.49931 (14)0.0480 (5)
C30.70229 (17)−0.0678 (2)0.46053 (15)0.0528 (5)
C40.78997 (17)0.0206 (2)0.52812 (14)0.0495 (5)
H4A0.76750.11260.51200.059*
H4B0.85420.00720.51570.059*
C50.82206 (14)0.00286 (17)0.63608 (13)0.0395 (4)
H50.77060.05360.65340.047*
C60.64617 (19)−0.3065 (2)0.42125 (16)0.0658 (7)
H6A0.6349−0.38900.44790.099*
H6B0.7004−0.31880.39640.099*
H6C0.5798−0.27890.37050.099*
C70.59232 (17)−0.1729 (3)0.53339 (19)0.0726 (7)
H7A0.5767−0.25370.55930.109*
H7B0.5287−0.14370.48020.109*
H7C0.6149−0.10500.58190.109*
C80.88456 (15)−0.28756 (17)0.57008 (12)0.0379 (4)
C90.90707 (17)−0.2532 (2)0.49221 (14)0.0493 (5)
H90.8574−0.20260.44300.059*
C101.00201 (19)−0.2928 (2)0.48641 (15)0.0560 (6)
H101.0167−0.26860.43410.067*
C111.07354 (17)−0.3676 (2)0.55817 (16)0.0535 (5)
C121.05468 (17)−0.4051 (2)0.63625 (15)0.0530 (5)
H121.1047−0.45660.68460.064*
C130.96006 (15)−0.36480 (19)0.64150 (13)0.0440 (5)
H130.9462−0.38990.69420.053*
C140.82422 (14)−0.17695 (19)0.74942 (13)0.0399 (4)
C150.84427 (18)−0.0661 (2)0.82215 (14)0.0524 (5)
H15A0.79460.00680.79290.063*
H15B0.9172−0.03250.84080.063*
C160.93284 (15)0.06468 (18)0.68828 (13)0.0402 (4)
C171.02557 (16)0.0042 (2)0.69010 (15)0.0493 (5)
H171.0217−0.08190.66610.059*
C181.12403 (17)0.0696 (2)0.72703 (16)0.0586 (6)
H181.18620.02890.72780.070*
C191.12733 (17)0.1957 (2)0.76238 (15)0.0566 (6)
C201.03892 (18)0.2570 (2)0.76548 (15)0.0554 (6)
H201.04430.34140.79250.066*
C210.94109 (17)0.1907 (2)0.72754 (14)0.0483 (5)
H210.87980.23150.72840.058*
N10.81566 (12)−0.13914 (14)0.66131 (10)0.0366 (4)
O10.81730 (12)−0.29307 (13)0.77065 (9)0.0514 (4)
O20.65146 (16)−0.03393 (17)0.37891 (11)0.0883 (6)
F11.22180 (11)0.26360 (14)0.79297 (12)0.0865 (5)
F21.16548 (11)−0.40863 (16)0.55128 (10)0.0810 (5)
Cl10.82752 (6)−0.12066 (7)0.92455 (4)0.0788 (2)
U11U22U33U12U13U23
C10.0399 (10)0.0328 (9)0.0374 (10)−0.0039 (8)0.0116 (8)0.0023 (7)
C20.0406 (11)0.0451 (11)0.0462 (11)−0.0035 (9)0.0049 (9)0.0039 (9)
C30.0533 (12)0.0460 (12)0.0462 (12)0.0049 (10)0.0068 (10)0.0079 (9)
C40.0551 (12)0.0385 (11)0.0475 (11)−0.0011 (9)0.0131 (10)0.0088 (8)
C50.0398 (10)0.0331 (9)0.0450 (10)0.0005 (8)0.0165 (8)0.0021 (8)
C60.0652 (15)0.0552 (14)0.0524 (13)−0.0129 (11)−0.0017 (11)0.0000 (10)
C70.0391 (12)0.0891 (18)0.0793 (17)0.0016 (12)0.0132 (11)0.0083 (14)
C80.0435 (10)0.0326 (9)0.0356 (9)−0.0046 (8)0.0139 (8)−0.0030 (7)
C90.0580 (13)0.0489 (12)0.0391 (11)0.0019 (10)0.0177 (10)0.0035 (9)
C100.0683 (14)0.0617 (14)0.0473 (12)−0.0067 (11)0.0329 (11)−0.0053 (10)
C110.0484 (12)0.0604 (13)0.0554 (13)−0.0021 (10)0.0248 (10)−0.0176 (11)
C120.0488 (12)0.0577 (13)0.0473 (12)0.0078 (10)0.0138 (10)−0.0019 (10)
C130.0481 (11)0.0456 (11)0.0373 (10)0.0021 (9)0.0162 (9)0.0016 (8)
C140.0371 (10)0.0427 (11)0.0434 (10)−0.0002 (8)0.0199 (8)0.0021 (8)
C150.0667 (14)0.0494 (12)0.0476 (12)0.0031 (10)0.0299 (11)0.0005 (9)
C160.0444 (11)0.0374 (10)0.0389 (10)−0.0043 (8)0.0168 (8)0.0033 (8)
C170.0474 (12)0.0377 (10)0.0588 (13)−0.0013 (9)0.0173 (10)0.0013 (9)
C180.0412 (12)0.0545 (13)0.0726 (15)0.0002 (10)0.0152 (11)0.0066 (11)
C190.0460 (12)0.0532 (13)0.0582 (13)−0.0159 (10)0.0084 (10)0.0044 (10)
C200.0652 (14)0.0450 (12)0.0548 (13)−0.0138 (11)0.0230 (11)−0.0084 (9)
C210.0542 (12)0.0440 (11)0.0520 (12)−0.0063 (9)0.0268 (10)−0.0052 (9)
N10.0377 (8)0.0338 (8)0.0383 (8)−0.0020 (6)0.0154 (7)0.0011 (6)
O10.0692 (10)0.0427 (8)0.0495 (8)−0.0042 (7)0.0313 (7)0.0050 (6)
O20.1047 (14)0.0628 (11)0.0543 (10)−0.0054 (10)−0.0126 (9)0.0190 (8)
F10.0524 (8)0.0701 (9)0.1148 (12)−0.0234 (7)0.0107 (8)−0.0013 (8)
F20.0621 (9)0.1066 (12)0.0843 (10)0.0072 (8)0.0400 (8)−0.0227 (8)
Cl10.1233 (6)0.0731 (4)0.0600 (4)−0.0112 (4)0.0577 (4)−0.0075 (3)
C1—N11.483 (2)C10—C111.357 (3)
C1—C81.519 (3)C10—H100.9300
C1—C21.542 (2)C11—F21.353 (2)
C1—H10.9800C11—C121.368 (3)
C2—C31.507 (3)C12—C131.375 (3)
C2—C61.530 (3)C12—H120.9300
C2—C71.541 (3)C13—H130.9300
C3—O21.203 (2)C14—O11.221 (2)
C3—C41.505 (3)C14—N11.356 (2)
C4—C51.535 (3)C14—C151.515 (3)
C4—H4A0.9700C15—Cl11.754 (2)
C4—H4B0.9700C15—H15A0.9700
C5—N11.485 (2)C15—H15B0.9700
C5—C161.517 (2)C16—C211.382 (3)
C5—H50.9800C16—C171.383 (3)
C6—H6A0.9600C17—C181.384 (3)
C6—H6B0.9600C17—H170.9300
C6—H6C0.9600C18—C191.367 (3)
C7—H7A0.9600C18—H180.9300
C7—H7B0.9600C19—F11.353 (2)
C7—H7C0.9600C19—C201.362 (3)
C8—C91.384 (3)C20—C211.382 (3)
C8—C131.389 (3)C20—H200.9300
C9—C101.381 (3)C21—H210.9300
C9—H90.9300
N1—C1—C8110.21 (14)C8—C9—H9119.5
N1—C1—C2109.50 (14)C11—C10—C9119.07 (19)
C8—C1—C2119.33 (16)C11—C10—H10120.5
N1—C1—H1105.6C9—C10—H10120.5
C8—C1—H1105.6F2—C11—C10118.9 (2)
C2—C1—H1105.6F2—C11—C12119.0 (2)
C3—C2—C6111.25 (17)C10—C11—C12122.1 (2)
C3—C2—C7105.53 (18)C11—C12—C13118.4 (2)
C6—C2—C7109.02 (18)C11—C12—H12120.8
C3—C2—C1110.54 (15)C13—C12—H12120.8
C6—C2—C1111.49 (16)C12—C13—C8121.65 (18)
C7—C2—C1108.80 (17)C12—C13—H13119.2
O2—C3—C4120.44 (19)C8—C13—H13119.2
O2—C3—C2122.40 (19)O1—C14—N1122.96 (17)
C4—C3—C2117.15 (16)O1—C14—C15120.95 (17)
C3—C4—C5118.07 (17)N1—C14—C15116.09 (16)
C3—C4—H4A107.8C14—C15—Cl1112.00 (14)
C5—C4—H4A107.8C14—C15—H15A109.2
C3—C4—H4B107.8Cl1—C15—H15A109.2
C5—C4—H4B107.8C14—C15—H15B109.2
H4A—C4—H4B107.1Cl1—C15—H15B109.2
N1—C5—C16113.80 (14)H15A—C15—H15B107.9
N1—C5—C4111.60 (15)C21—C16—C17118.52 (18)
C16—C5—C4107.94 (15)C21—C16—C5119.36 (17)
N1—C5—H5107.8C17—C16—C5121.83 (17)
C16—C5—H5107.8C16—C17—C18121.11 (19)
C4—C5—H5107.8C16—C17—H17119.4
C2—C6—H6A109.5C18—C17—H17119.4
C2—C6—H6B109.5C19—C18—C17118.1 (2)
H6A—C6—H6B109.5C19—C18—H18121.0
C2—C6—H6C109.5C17—C18—H18121.0
H6A—C6—H6C109.5F1—C19—C20118.8 (2)
H6B—C6—H6C109.5F1—C19—C18118.4 (2)
C2—C7—H7A109.5C20—C19—C18122.8 (2)
C2—C7—H7B109.5C19—C20—C21118.3 (2)
H7A—C7—H7B109.5C19—C20—H20120.8
C2—C7—H7C109.5C21—C20—H20120.8
H7A—C7—H7C109.5C20—C21—C16121.1 (2)
H7B—C7—H7C109.5C20—C21—H21119.4
C9—C8—C13117.70 (18)C16—C21—H21119.4
C9—C8—C1125.28 (17)C14—N1—C1117.35 (14)
C13—C8—C1116.97 (16)C14—N1—C5122.27 (15)
C10—C9—C8121.09 (19)C1—N1—C5119.95 (14)
C10—C9—H9119.5
N1—C1—C2—C358.3 (2)C1—C8—C13—C12−177.07 (17)
C8—C1—C2—C3−70.0 (2)O1—C14—C15—Cl1−12.3 (2)
N1—C1—C2—C6−177.45 (16)N1—C14—C15—Cl1168.29 (14)
C8—C1—C2—C654.3 (2)N1—C5—C16—C21−135.35 (17)
N1—C1—C2—C7−57.2 (2)C4—C5—C16—C21100.2 (2)
C8—C1—C2—C7174.54 (17)N1—C5—C16—C1750.9 (2)
C6—C2—C3—O231.2 (3)C4—C5—C16—C17−73.6 (2)
C7—C2—C3—O2−86.9 (3)C21—C16—C17—C18−2.4 (3)
C1—C2—C3—O2155.6 (2)C5—C16—C17—C18171.43 (18)
C6—C2—C3—C4−147.7 (2)C16—C17—C18—C190.4 (3)
C7—C2—C3—C494.2 (2)C17—C18—C19—F1−175.83 (19)
C1—C2—C3—C4−23.3 (3)C17—C18—C19—C202.2 (3)
O2—C3—C4—C5157.1 (2)F1—C19—C20—C21175.26 (19)
C2—C3—C4—C5−23.9 (3)C18—C19—C20—C21−2.8 (3)
C3—C4—C5—N135.1 (2)C19—C20—C21—C160.7 (3)
C3—C4—C5—C16160.89 (18)C17—C16—C21—C201.8 (3)
N1—C1—C8—C9−105.5 (2)C5—C16—C21—C20−172.16 (18)
C2—C1—C8—C922.4 (3)O1—C14—N1—C16.3 (3)
N1—C1—C8—C1372.05 (19)C15—C14—N1—C1−174.27 (16)
C2—C1—C8—C13−160.01 (16)O1—C14—N1—C5178.74 (17)
C13—C8—C9—C10−0.9 (3)C15—C14—N1—C5−1.8 (2)
C1—C8—C9—C10176.67 (18)C8—C1—N1—C14−103.14 (17)
C8—C9—C10—C110.6 (3)C2—C1—N1—C14123.70 (17)
C9—C10—C11—F2178.63 (18)C8—C1—N1—C584.23 (18)
C9—C10—C11—C120.0 (3)C2—C1—N1—C5−48.9 (2)
F2—C11—C12—C13−178.82 (18)C16—C5—N1—C1467.7 (2)
C10—C11—C12—C13−0.2 (3)C4—C5—N1—C14−169.80 (16)
C11—C12—C13—C8−0.2 (3)C16—C5—N1—C1−120.01 (17)
C9—C8—C13—C120.7 (3)C4—C5—N1—C12.4 (2)
D—H···AD—HH···AD···AD—H···A
C5—H5···O1i0.982.503.453 (2)165
C15—H15A···O1i0.972.463.429 (3)174
C20—H20···O2ii0.932.453.298 (3)151
C10—H10···Cg1iii0.932.663.499 (2)151
C17—H17···Cg20.932.853.771 (2)170
  7 in total

1.  The Cambridge Structural Database: a quarter of a million crystal structures and rising.

Authors:  Frank H Allen
Journal:  Acta Crystallogr B       Date:  2002-05-29

2.  A short history of SHELX.

Authors:  George M Sheldrick
Journal:  Acta Crystallogr A       Date:  2007-12-21       Impact factor: 2.290

3.  r-2,c-6-Bis(4-fluoro-phen-yl)-t-3,t-5-dimethyl-piperidin-4-one.

Authors:  D Gayathri; D Velmurugan; G Aridoss; S Kabilan; K Ravikumar
Journal:  Acta Crystallogr Sect E Struct Rep Online       Date:  2008-01-11

4.  r-2,c-6-Bis(4-chloro-phen-yl)-c-3,t-3-dimethyl-piperidin-4-one.

Authors:  S S Ilango; S Ponnuswamy; P Gayathri; A Thiruvalluvar; R J Butcher
Journal:  Acta Crystallogr Sect E Struct Rep Online       Date:  2008-11-13

5.  Synthesis and NMR spectral studies of N-chloroacetyl-2,6-diarylpiperidin-4-ones.

Authors:  G Aridoss; S Balasubramanian; P Parthiban; S Kabilan
Journal:  Spectrochim Acta A Mol Biomol Spectrosc       Date:  2007-01-20       Impact factor: 4.098

6.  r-2,c-6-Bis(4-chloro-phen-yl)-t-3-isopropyl-1-nitro-sopiperidin-4-one.

Authors:  P Gayathri; A Thiruvalluvar; A Manimekalai; S Sivakumar; R J Butcher
Journal:  Acta Crystallogr Sect E Struct Rep Online       Date:  2008-09-20

7.  Structure validation in chemical crystallography.

Authors:  Anthony L Spek
Journal:  Acta Crystallogr D Biol Crystallogr       Date:  2009-01-20
  7 in total

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