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Crystal structure of rac-2,3-di­phenyl-2,3,5,6-tetra­hydro-4H-1,3-thiazin-4-one 1-oxide

CROSSMARK_Color_square_no_text.svg

aDepartment of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA, and bPennsylvania State University, Schuylkill Campus, 200 University Drive, Schuylkill Haven, PA 17972, USA
*Correspondence e-mail: ljs43@psu.edu

Edited by M. Gdaniec, Adam Mickiewicz University, Poland (Received 10 August 2016; accepted 30 September 2016; online 7 October 2016)

In the title compound, C16H15NO2S [alternative name: rac-2,3-diphenyl-1,3-thia­zinan-4-one 1-oxide], the thia­zine ring exhibits an envelope conformation, with the S atom forming the flap. The sulfoxide O atom is in a pseudo-axial position on the thia­zine ring and is trans to the phenyl group on C-2. The phenyl rings form a dihedral angle of 89.47 (19)°. In this racemate crystal, homochiral mol­ecules form slabs parallel to (010) of thickness b/2 which then stack with alternating chirality in the b-axis direction. The stacking is aided by edge-to-face inter­actions between the phenyl rings of racemic mol­ecules. Within each of the single-enanti­omer slabs, the mol­ecules are held by C—H⋯O-type inter­actions, with an H⋯O distance of 2.30 Å, forming infinite chains along the c-axis direction, as well by the edge-to-face inter­actions between phenyl rings of neighboring mol­ecules in the a-axis direction.

1. Chemical context

1,3-Thia­zin-4-ones are a group of six-membered heterocycles with a wide range of biological activity (Ryabukhin et al., 1996[Ryabukhin, Y. I., Korzhavina, O. B. & Suzdalev, K. F. (1996). Adv. Heterocycl. Chem. 66, 131-190.]). Surrey's research (Surrey et al., 1958[Surrey, A. R., Webb, W. G. & Gesler, R. M. (1958). J. Am. Chem. Soc. 80, 3469-3471.]; Surrey, 1963a[Surrey, A. R. (1963a). US Patent 3082209.]) resulted in the discovery of two drugs, the anti-anxiety and muscle relaxant chlormezanone [2-(4-chloro­phen­yl)-3-methyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one 1,1-dioxide; Merck Index, 2006[Merck Index (2006). 14th ed., edited by M. J. O'Neil, p. 349. Whitehouse Station: Merck & Co.]; Tanaka & Hirayama, 2005[Tanaka, R. & Horayama, N. (2005). X-Ray Struct. Anal. Online, 21, x57-x58.]] and muscle relaxant dichlormezanone [2-(3,4-di­chloro­phen­yl)-3-methyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one 1,1-dioxide; Dictionary of Drugs, 1990[Dictionary of Drugs (1990). Edited by J. Elks & C. R. Ganellin, p. 382. Cambridge: Chapman and Hall.]]. These sulfones showed greater activity than the sulfides from which they were synthesized (Surrey et al., 1958[Surrey, A. R., Webb, W. G. & Gesler, R. M. (1958). J. Am. Chem. Soc. 80, 3469-3471.]). Surrey also prepared a variety of other sulfoxides and sulfones of 3-alkyl-2-aryl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-ones (Surrey, 1963a[Surrey, A. R. (1963a). US Patent 3082209.],b[Surrey, A. R. (1963b). US Patent 3093639.]). Surrey did not successfully synthesize any 2-aryl-3-aryl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-ones (Silverberg et al., 2015[Silverberg, L. J., Pacheco, C. N., Lagalante, A., Cannon, K. C., Bachert, J. T., Xie, Y., Baker, L. & Bayliff, J. A. (2015). Int. J. Chem. (Toronto, ON, Can.), 7(2), 150-162.]), and to the best of our knowledge nobody has reported any oxides of this type of compound. We previously reported the crystal structure of 2,3-diphenyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one (Yennawar & Silverberg, 2014[Yennawar, H. P. & Silverberg, L. J. (2014). Acta Cryst. E70, o133.]). Herein, we report the crystal structure of that compound's sulfoxide, prepared using the method we have previously reported for oxidation of the five-membered 1,3-thia­zolidin-4-ones (Cannon et al., 2015[Cannon, K., Gandla, D., Lauro, S., Silverberg, L., Tierney, J. & Lagalante, A. (2015). Int. J. Chem. (Toronto, ON, Can.), 7(2), 73-84.]).

2. Structural commentary

The crystal structure of this racemic compound shows a thia­zine ring in an envelope pucker with puckering amplitude of 0.718 (3) Å (Fig. 1[link]). The oxygen on sulfur is pseudo-axial on the thia­zine ring. The two phenyl rings, on two adjacent atoms of the thia­zine ring, are perpendicular to each other with an angle of 89.47 (19)° between their planes. The oxygen on sulfur and the phenyl ring on C2 are trans to each other.

[Scheme 1]
[Figure 1]
Figure 1
The mol­ecular conformation and atom-numbering scheme for the title compound, with non-H atoms shown as 50% probability displacement ellipsoids.

3. Supra­molecular features

The crystal consists of a racemic mixture of the title compound. The two phenyl groups and one of the two oxygen atoms participate in inter­molecular inter­actions (Table 1[link]). The mol­ecules of single chirality form slabs in the ac plane aided by ππ edge-to-face inter­actions, with inter-centroid distance of 5.195 (3) Å, in the a-axis direction and with C—H⋯O hydrogen-bonds (Table 1[link]) in the c-axis direction (Fig. 2[link]). Along the b-axis direction, these slabs stack with alternating chirality, stabilized once again by ππ edge-to-face inter­actions with inter-centroid distances of 5.021 (3) Å.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C1—H1⋯O1i 0.98 2.30 3.261 (5) 167
Symmetry code: (i) [-x, -y+1, z-{\script{1\over 2}}].
[Figure 2]
Figure 2
Packing viewed down the c axis. Alternating slabs of enanti­omers along the b-axis direction are differentiated by the color scheme.

4. Database survey

Crystal structures of a number of 1,3-thia­zolidin-4-one 1-oxides have been reported (Wang et al., 2010[Wang, Q., Xu, Z. & Sun, Y. (2010). Acta Cryst. E66, o1422.]; Johnson et al., 1983[Johnson, M. R., Fazio, M. J., Ward, D. L. & Sousa, L. R. (1983). J. Org. Chem. 48, 494-499.]; Chen et al., 2011[Chen, H., Zai-Hong, G., Qing-Mei, Y. & Xiao-Liu, L. (2011). Chin. J. Org. Chem. 31, 249-255.]; Colombo et al., 2008[Colombo, A., Fernàndez, J. C., Fernández-Forner, D., de la Figuera, N., Albericio, F. & Forns, P. (2008). Tetrahedron Lett. 49, 1569-1572.]; Yennawar et al., 2015[Yennawar, H. P., Tierney, J., Hullihen, P. D. & Silverberg, L. J. (2015). Acta Cryst. E71, 264-267.]); in each case the oxygen on sulfur and the group on C-2 had a trans relationship, as does the structure reported here. The structure of chlormezanone [2-(4-chloro­phen­yl)-3-methyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one 1,1-dioxide] has also been disclosed (Tanaka & Horayama, 2005[Tanaka, R. & Horayama, N. (2005). X-Ray Struct. Anal. Online, 21, x57-x58.]). To the best of our knowledge, there have been no published crystal structures of a 2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one 1-oxide.

5. Synthesis and crystallization

A 5 mL round-bottom flask was charged with 50.5 mg of 2,3-diphenyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one and 1.5 mL of methanol and stirred. A solution of 85.6 mg Oxone® and 0.74 mL distilled water was added dropwise and the mixture was stirred until the reaction was complete as determined by TLC. The solids were dissolved by addition of 7.4 mL distilled water. The solution was extracted with 7.4 mL di­chloro­methane. The organic layer was washed with distilled water and then with sat. sodium chloride. The solution was dried over Na2SO4 and concentrated under vacuum to a crude solid. This was chromatographed on flash silica gel, eluting with 70% ethyl acetate/hexa­nes, 100% ethyl acetate, and 100% acetone, giving 37.5 mg product (70% yield), m.p.: 396–400 K, Rf = 0.23 (EtOAc). Crystals for X-ray crystallography were grown by slow evaporation from ethanol solution.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. The hydrogen atoms were placed geometrically and allowed to ride on the carbon atoms during refinement, with C—H distances of 0.98 Å (methine), 0.96 Å (meth­yl) and 0.93 Å (aromatic) and with Uiso(H) = 1.2Ueq(aromatic and methine C) or 1.5Ueq(meth­yl).

Table 2
Experimental details

Crystal data
Chemical formula C16H15NO2S
Mr 285.35
Crystal system, space group Orthorhombic, Pna21
Temperature (K) 298
a, b, c (Å) 10.547 (4), 17.317 (6), 7.592 (3)
V3) 1386.5 (8)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.23
Crystal size (mm) 0.23 × 0.18 × 0.16
 
Data collection
Diffractometer Bruker SMART APEX CCD area detector
Absorption correction Multi-scan (SADABS; Bruker, 2001[Bruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.636, 0.964
No. of measured, independent and observed [I > 2σ(I)] reflections 11124, 3428, 3182
Rint 0.032
(sin θ/λ)max−1) 0.668
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.075, 0.161, 1.26
No. of reflections 3428
No. of parameters 181
No. of restraints 1
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.38, −0.27
Absolute structure Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 4716 Friedel pairs
Absolute structure parameter 0.12 (14)
Computer programs: SMART and SAINT (Bruker, 2001[Bruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Supporting information


Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

rac-2,3-Diphenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one 1-oxide top
Crystal data top
C16H15NO2SDx = 1.367 Mg m3
Mr = 285.35Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pna21Cell parameters from 3661 reflections
a = 10.547 (4) Åθ = 2.3–26.4°
b = 17.317 (6) ŵ = 0.23 mm1
c = 7.592 (3) ÅT = 298 K
V = 1386.5 (8) Å3Block, colorless
Z = 40.23 × 0.18 × 0.16 mm
F(000) = 600
Data collection top
Bruker SMART APEX CCD area detector
diffractometer
3428 independent reflections
Radiation source: fine-focus sealed tube3182 reflections with I > 2σ(I)
Parallel,graphite monochromatorRint = 0.032
φ and ω scansθmax = 28.3°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
h = 1313
Tmin = 0.636, Tmax = 0.964k = 2023
11124 measured reflectionsl = 1010
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.075H-atom parameters constrained
wR(F2) = 0.161 w = 1/[σ2(Fo2) + (0.0582P)2 + 0.8049P]
where P = (Fo2 + 2Fc2)/3
S = 1.26(Δ/σ)max < 0.001
3428 reflectionsΔρmax = 0.38 e Å3
181 parametersΔρmin = 0.27 e Å3
1 restraintAbsolute structure: Flack (1983), 4716 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.12 (14)
Special details top

Experimental. 1. SADABS was used for absorption correction. R(int) was 0.0424 before and 0.0268 after correction. The Ratio of minimum to maximum transmission is 0.6364. The λ/2 correction factor is 0.0015.

2. The data collection nominally covered a full sphere of reciprocal space by a combination of 4 sets of ω scans each set at different φ and/or 2θ angles and each scan (5 s exposure) covering -0.300° degrees in ω. The crystal to detector distance was 5.82 cm.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S10.17133 (10)0.45935 (5)1.97816 (14)0.0469 (3)
O10.0575 (3)0.44303 (18)1.8700 (4)0.0659 (9)
O20.0431 (3)0.23452 (16)2.0769 (4)0.0542 (8)
N10.0796 (2)0.34956 (15)2.2011 (4)0.0281 (6)
C10.1326 (3)0.42779 (19)2.2029 (4)0.0304 (7)
H10.06460.46192.24420.036*
C20.1038 (4)0.2938 (2)2.0808 (5)0.0375 (8)
C30.2109 (4)0.3050 (2)1.9494 (5)0.0483 (10)
H3A0.17710.29361.83340.058*
H3B0.27450.26601.97440.058*
C40.2783 (4)0.3813 (3)1.9375 (5)0.0521 (11)
H4A0.34650.38282.02310.063*
H4B0.31510.38701.82110.063*
C50.2437 (3)0.44151 (17)2.3232 (4)0.0278 (6)
C60.2671 (4)0.5164 (2)2.3791 (5)0.0392 (8)
H60.21260.55592.34460.047*
C70.3688 (4)0.5333 (3)2.4840 (8)0.0534 (10)
H70.38420.58392.51860.064*
C80.4485 (4)0.4748 (3)2.5384 (6)0.0517 (11)
H80.51750.48602.61030.062*
C90.4261 (3)0.4006 (2)2.4869 (6)0.0472 (9)
H90.47990.36132.52470.057*
C100.3245 (3)0.3830 (2)2.3791 (5)0.0391 (8)
H100.31020.33232.34410.047*
C110.0254 (3)0.33887 (18)2.3192 (4)0.0297 (7)
C120.1478 (4)0.3459 (2)2.2599 (5)0.0408 (8)
H120.16270.35622.14150.049*
C130.2485 (4)0.3378 (2)2.3733 (6)0.0477 (10)
H130.33130.34242.33230.057*
C140.2254 (4)0.3231 (2)2.5468 (5)0.0439 (9)
H140.29340.31712.62360.053*
C150.1043 (4)0.3169 (3)2.6103 (5)0.0492 (10)
H150.09010.30772.72940.059*
C160.0032 (4)0.3244 (2)2.4953 (5)0.0454 (9)
H160.07940.31972.53660.055*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0600 (6)0.0427 (5)0.0380 (4)0.0080 (4)0.0072 (5)0.0128 (4)
O10.083 (2)0.0605 (18)0.0548 (19)0.0131 (17)0.0259 (18)0.0026 (16)
O20.0614 (18)0.0366 (15)0.0648 (19)0.0055 (13)0.0023 (15)0.0188 (13)
N10.0242 (13)0.0277 (13)0.0325 (13)0.0015 (10)0.0013 (12)0.0054 (11)
C10.0326 (16)0.0262 (15)0.0323 (16)0.0012 (13)0.0013 (14)0.0026 (13)
C20.041 (2)0.0306 (17)0.0410 (19)0.0064 (14)0.0042 (16)0.0056 (15)
C30.049 (2)0.055 (2)0.041 (2)0.0142 (18)0.0079 (18)0.0038 (18)
C40.042 (2)0.080 (3)0.034 (2)0.003 (2)0.0060 (16)0.0044 (18)
C50.0233 (14)0.0287 (14)0.0316 (16)0.0045 (12)0.0070 (12)0.0007 (13)
C60.0376 (19)0.0357 (17)0.0441 (19)0.0002 (15)0.0024 (16)0.0036 (16)
C70.046 (2)0.057 (2)0.057 (2)0.0126 (18)0.003 (3)0.018 (2)
C80.0308 (19)0.081 (3)0.043 (2)0.017 (2)0.0064 (16)0.006 (2)
C90.0275 (16)0.064 (2)0.051 (2)0.0013 (16)0.0053 (19)0.012 (2)
C100.0344 (19)0.0370 (17)0.046 (2)0.0008 (14)0.0017 (16)0.0019 (17)
C110.0333 (17)0.0266 (14)0.0293 (15)0.0000 (12)0.0056 (14)0.0002 (13)
C120.0364 (19)0.047 (2)0.0388 (19)0.0003 (16)0.0021 (15)0.0013 (17)
C130.0287 (18)0.055 (2)0.059 (2)0.0006 (17)0.0004 (18)0.002 (2)
C140.042 (2)0.040 (2)0.050 (2)0.0065 (16)0.0185 (17)0.0007 (17)
C150.048 (2)0.073 (3)0.0261 (17)0.004 (2)0.0027 (17)0.0071 (18)
C160.0369 (18)0.062 (2)0.0374 (19)0.0022 (16)0.0089 (17)0.0001 (19)
Geometric parameters (Å, º) top
S1—O11.482 (3)C5—C101.390 (5)
S1—C11.838 (4)C6—C71.368 (6)
S1—C41.787 (5)C7—C81.379 (6)
O2—C21.210 (5)C8—C91.364 (6)
N1—C11.466 (4)C9—C101.383 (5)
N1—C21.354 (4)C11—C121.372 (5)
N1—C111.436 (4)C11—C161.380 (5)
C1—C51.505 (5)C12—C131.375 (6)
C2—C31.519 (5)C13—C141.363 (6)
C3—C41.503 (6)C14—C151.370 (6)
C5—C61.387 (5)C15—C161.384 (6)
O1—S1—C1106.12 (18)C6—C5—C10118.7 (3)
O1—S1—C4105.8 (2)C10—C5—C1123.2 (3)
C4—S1—C194.34 (17)C7—C6—C5121.1 (4)
C2—N1—C1126.4 (3)C6—C7—C8119.7 (4)
C2—N1—C11118.4 (3)C9—C8—C7120.1 (4)
C11—N1—C1114.0 (2)C8—C9—C10120.7 (4)
N1—C1—S1110.6 (2)C9—C10—C5119.7 (3)
N1—C1—C5116.7 (3)C12—C11—N1120.6 (3)
C5—C1—S1110.1 (2)C12—C11—C16119.5 (3)
O2—C2—N1121.4 (3)C16—C11—N1119.8 (3)
O2—C2—C3119.0 (3)C11—C12—C13120.8 (4)
N1—C2—C3119.5 (3)C14—C13—C12119.1 (4)
C4—C3—C2120.2 (3)C13—C14—C15121.4 (4)
C3—C4—S1110.9 (3)C14—C15—C16119.3 (4)
C6—C5—C1118.1 (3)C11—C16—C15119.9 (3)
S1—C1—C5—C676.3 (3)C2—N1—C11—C16109.6 (4)
S1—C1—C5—C10102.9 (3)C2—C3—C4—S134.5 (4)
O1—S1—C1—N149.2 (3)C4—S1—C1—N158.6 (3)
O1—S1—C1—C5179.5 (2)C4—S1—C1—C571.7 (3)
O1—S1—C4—C346.9 (3)C5—C6—C7—C81.3 (7)
O2—C2—C3—C4173.1 (4)C6—C5—C10—C90.6 (5)
N1—C1—C5—C6156.6 (3)C6—C7—C8—C90.3 (7)
N1—C1—C5—C1024.1 (4)C7—C8—C9—C100.5 (7)
N1—C2—C3—C48.0 (5)C8—C9—C10—C50.3 (6)
N1—C11—C12—C13178.2 (3)C10—C5—C6—C71.4 (6)
N1—C11—C16—C15177.7 (3)C11—N1—C1—S1139.1 (2)
C1—S1—C4—C361.2 (3)C11—N1—C1—C594.1 (3)
C1—N1—C2—O2170.2 (3)C11—N1—C2—O23.5 (5)
C1—N1—C2—C311.0 (5)C11—N1—C2—C3177.6 (3)
C1—N1—C11—C1295.3 (4)C11—C12—C13—C140.3 (6)
C1—N1—C11—C1682.2 (4)C12—C11—C16—C150.1 (6)
C1—C5—C6—C7177.9 (4)C12—C13—C14—C150.6 (6)
C1—C5—C10—C9178.7 (3)C13—C14—C15—C161.1 (7)
C2—N1—C1—S128.1 (4)C14—C15—C16—C110.8 (6)
C2—N1—C1—C598.7 (4)C16—C11—C12—C130.7 (6)
C2—N1—C11—C1272.9 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···O1i0.982.303.261 (5)167
Symmetry code: (i) x, y+1, z1/2.
 

Acknowledgements

We thank Penn State Schuylkill for financial support and NSF funding (CHEM-0131112) for the X-ray diffractometer.

References

First citationBruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCannon, K., Gandla, D., Lauro, S., Silverberg, L., Tierney, J. & Lagalante, A. (2015). Int. J. Chem. (Toronto, ON, Can.), 7(2), 73–84.  Google Scholar
First citationChen, H., Zai-Hong, G., Qing-Mei, Y. & Xiao-Liu, L. (2011). Chin. J. Org. Chem. 31, 249–255.  Google Scholar
First citationColombo, A., Fernàndez, J. C., Fernández-Forner, D., de la Figuera, N., Albericio, F. & Forns, P. (2008). Tetrahedron Lett. 49, 1569–1572.  Web of Science CSD CrossRef CAS Google Scholar
First citationDictionary of Drugs (1990). Edited by J. Elks & C. R. Ganellin, p. 382. Cambridge: Chapman and Hall.  Google Scholar
First citationDolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationJohnson, M. R., Fazio, M. J., Ward, D. L. & Sousa, L. R. (1983). J. Org. Chem. 48, 494–499.  CSD CrossRef CAS Web of Science Google Scholar
First citationMerck Index (2006). 14th ed., edited by M. J. O'Neil, p. 349. Whitehouse Station: Merck & Co.  Google Scholar
First citationRyabukhin, Y. I., Korzhavina, O. B. & Suzdalev, K. F. (1996). Adv. Heterocycl. Chem. 66, 131-190.  CrossRef CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSilverberg, L. J., Pacheco, C. N., Lagalante, A., Cannon, K. C., Bachert, J. T., Xie, Y., Baker, L. & Bayliff, J. A. (2015). Int. J. Chem. (Toronto, ON, Can.), 7(2), 150–162.  Google Scholar
First citationSurrey, A. R. (1963a). US Patent 3082209.  Google Scholar
First citationSurrey, A. R. (1963b). US Patent 3093639.  Google Scholar
First citationSurrey, A. R., Webb, W. G. & Gesler, R. M. (1958). J. Am. Chem. Soc. 80, 3469–3471.  CrossRef CAS Web of Science Google Scholar
First citationTanaka, R. & Horayama, N. (2005). X-Ray Struct. Anal. Online, 21, x57–x58.  Google Scholar
First citationWang, Q., Xu, Z. & Sun, Y. (2010). Acta Cryst. E66, o1422.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationYennawar, H. P. & Silverberg, L. J. (2014). Acta Cryst. E70, o133.  CSD CrossRef IUCr Journals Google Scholar
First citationYennawar, H. P., Tierney, J., Hullihen, P. D. & Silverberg, L. J. (2015). Acta Cryst. E71, 264–267.  Web of Science CSD CrossRef IUCr Journals Google Scholar

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