organic compounds
2,3-Diphenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one
aDepartment of Chemistry, 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
In the title compound, C20H15NOS, the dihedral angle between the phenyl rings is 74.25 (6)°. The six-membered 1,3-thiazine ring has an with the C atom at the 2-position forming the flap. The features weak C—H⋯O interactions, which lead to the formation of a tape motif along [110].
CCDC reference: 992181
Related literature
For other preparations of the title compound, see: Ponci et al. (1963); Kollenz & Ziegler (1970); Oae & Numata (1974); Badea et al. (1998). For previously published methods for the preparation of 1,3-thiazin-4-ones by condensation of an imine with a thioacid, see: Kamel et al. (2010); Zarghi et al. (2009); Zhou et al. (2008); Srivastava et al. (2002). For the synthesis and crystal structures of related compounds, see: Yennawar & Silverberg (2013, 2014); Yennawar et al. (2013).
Experimental
Crystal data
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Data collection: SMART (Bruker, 2001); cell SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XSHELL in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: ORTEP-3 for Windows (Farrugia, 2012).
Supporting information
CCDC reference: 992181
10.1107/S1600536814005881/fy2112sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814005881/fy2112Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814005881/fy2112Isup3.mol
Supporting information file. DOI: 10.1107/S1600536814005881/fy2112Isup4.cml
A two-necked 25 ml roundbottom flask was oven-dried, cooled under N2, and charged with a stir bar and N-benzylideneaniline (1.02 g, 6 mmol). Tetrahydrofuran (2.3 ml) was added, the solid dissolved, and the solution was stirred. Pyridine (1.95 ml, 24 mmol) was added and then thiosalicylic acid (0.931 g, 6 mmol) was added. Finally, 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphorinane-2,4,6-trioxatriphosphorinane-2,4,6-trioxide in 2-methyltetrahydrofuran (50 weight percent; 7.1 ml, 12 mmol) was added. The reaction was stirred at room temperature for 21 h, then poured into a separatory funnel and extracted three times with ethyl acetate. The organic was washed with saturated sodium bicarbonate, water and saturated sodium chloride. The solution was concentrated in vacuo, and then the solid was slurried in hot hexanes. After cooling in ice, the solid was collected by vacuum filtration and rinsed with cold hexanes to give a light orange solid (0.8697 g, m.p. 129–133°C). The solid was then recrystallized from ethanol, yielding solid that was still impure by TLC and melting point [0.5921 g, m.p. 132–134°C (lit. 138–140°C; Ponci et al., 1963)]. Rf = 0.33 (20% EtOAc/hexanes). Crystals for X-ray crystallography were grown by slow evaporation from toluene.
The C-bound H atoms were geometrically placed with C—H = 0.93–0.97 Å, and refined as riding with Uiso(H) = 1.2 Ueq(C).
Data collection: SMART (Bruker, 2001); cell
SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XSHELL in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: ORTEP-3 for Windows (Farrugia, 2012).Fig. 1. ORTEP view of the title comound. Thermal ellipsoids are drawn at 50% probability. | |
Fig. 2. Crystal packing. C—H···O interactions are shown as dashed lines. |
C20H15NOS | F(000) = 1328 |
Mr = 317.39 | Dx = 1.334 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 14.799 (4) Å | Cell parameters from 4538 reflections |
b = 9.606 (3) Å | θ = 2.5–28.0° |
c = 22.492 (6) Å | µ = 0.21 mm−1 |
β = 98.736 (5)° | T = 298 K |
V = 3160.1 (15) Å3 | Block, colourless |
Z = 8 | 0.18 × 0.16 × 0.05 mm |
Bruker SMART APEX CCD area-detector diffractometer | 3956 independent reflections |
Radiation source: fine-focus sealed tube | 3300 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
Detector resolution: 8.34 pixels mm-1 | θmax = 28.4°, θmin = 1.8° |
ϕ and ω scans | h = −18→19 |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | k = −12→12 |
Tmin = 0.963, Tmax = 0.990 | l = −30→30 |
14747 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.051 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.127 | H-atom parameters not refined |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0565P)2 + 1.8423P] where P = (Fo2 + 2Fc2)/3 |
3956 reflections | (Δ/σ)max < 0.001 |
208 parameters | Δρmax = 0.28 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C20H15NOS | V = 3160.1 (15) Å3 |
Mr = 317.39 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 14.799 (4) Å | µ = 0.21 mm−1 |
b = 9.606 (3) Å | T = 298 K |
c = 22.492 (6) Å | 0.18 × 0.16 × 0.05 mm |
β = 98.736 (5)° |
Bruker SMART APEX CCD area-detector diffractometer | 3956 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 3300 reflections with I > 2σ(I) |
Tmin = 0.963, Tmax = 0.990 | Rint = 0.021 |
14747 measured reflections |
R[F2 > 2σ(F2)] = 0.051 | 0 restraints |
wR(F2) = 0.127 | H-atom parameters not refined |
S = 1.06 | Δρmax = 0.28 e Å−3 |
3956 reflections | Δρmin = −0.25 e Å−3 |
208 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.03935 (11) | 0.32561 (17) | 0.11547 (7) | 0.0434 (4) | |
C2 | 0.01411 (11) | 0.46594 (17) | 0.13594 (7) | 0.0434 (4) | |
C3 | 0.04910 (12) | 0.58978 (17) | 0.11600 (7) | 0.0460 (4) | |
C4 | 0.18665 (11) | 0.42745 (15) | 0.09649 (7) | 0.0406 (3) | |
H4 | 0.2301 | 0.4022 | 0.0695 | 0.049* | |
C5 | 0.24251 (10) | 0.45006 (15) | 0.15831 (7) | 0.0377 (3) | |
C6 | 0.23025 (12) | 0.37177 (17) | 0.20814 (8) | 0.0469 (4) | |
H6 | 0.1848 | 0.3041 | 0.2048 | 0.056* | |
C7 | 0.28512 (13) | 0.3933 (2) | 0.26298 (8) | 0.0557 (4) | |
H7 | 0.2759 | 0.3408 | 0.2963 | 0.067* | |
C8 | 0.35351 (13) | 0.4925 (2) | 0.26842 (9) | 0.0559 (4) | |
H8 | 0.3903 | 0.5069 | 0.3052 | 0.067* | |
C9 | 0.36669 (12) | 0.56958 (17) | 0.21908 (9) | 0.0519 (4) | |
H9 | 0.4131 | 0.6357 | 0.2225 | 0.062* | |
C10 | 0.31166 (11) | 0.54979 (16) | 0.16442 (8) | 0.0442 (4) | |
H10 | 0.3208 | 0.6034 | 0.1314 | 0.053* | |
C11 | 0.14103 (11) | 0.18738 (16) | 0.06409 (7) | 0.0393 (3) | |
C12 | 0.21265 (16) | 0.1052 (2) | 0.08852 (9) | 0.0657 (6) | |
H12 | 0.2492 | 0.1317 | 0.1241 | 0.079* | |
C13 | 0.23063 (18) | −0.0177 (2) | 0.06018 (10) | 0.0759 (7) | |
H13 | 0.2795 | −0.0733 | 0.0767 | 0.091* | |
C14 | 0.17703 (15) | −0.05742 (19) | 0.00829 (9) | 0.0592 (5) | |
H14 | 0.1882 | −0.1412 | −0.0100 | 0.071* | |
C15 | 0.10730 (15) | 0.0256 (2) | −0.01663 (9) | 0.0670 (6) | |
H15 | 0.0715 | −0.0005 | −0.0525 | 0.080* | |
C16 | 0.08922 (14) | 0.1488 (2) | 0.01100 (8) | 0.0603 (5) | |
H16 | 0.0417 | 0.2057 | −0.0065 | 0.072* | |
C17 | −0.05168 (12) | 0.4728 (2) | 0.17424 (8) | 0.0514 (4) | |
H17 | −0.0753 | 0.3909 | 0.1877 | 0.062* | |
C18 | −0.08209 (14) | 0.5990 (2) | 0.19226 (9) | 0.0619 (5) | |
H18 | −0.1253 | 0.6023 | 0.2182 | 0.074* | |
C19 | −0.04820 (14) | 0.7204 (2) | 0.17166 (10) | 0.0660 (6) | |
H19 | −0.0696 | 0.8056 | 0.1834 | 0.079* | |
C20 | 0.01695 (14) | 0.7175 (2) | 0.13392 (9) | 0.0583 (5) | |
H20 | 0.0394 | 0.8002 | 0.1204 | 0.070* | |
N1 | 0.12016 (9) | 0.31448 (13) | 0.09313 (6) | 0.0408 (3) | |
O1 | −0.01007 (9) | 0.22507 (14) | 0.11818 (6) | 0.0617 (4) | |
S1 | 0.13067 (3) | 0.58704 (5) | 0.06672 (2) | 0.05412 (16) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0430 (9) | 0.0427 (8) | 0.0451 (8) | −0.0043 (7) | 0.0089 (7) | −0.0052 (7) |
C2 | 0.0396 (8) | 0.0446 (9) | 0.0443 (8) | 0.0026 (7) | 0.0007 (6) | −0.0060 (7) |
C3 | 0.0447 (9) | 0.0441 (9) | 0.0454 (8) | 0.0056 (7) | −0.0049 (7) | −0.0001 (7) |
C4 | 0.0427 (8) | 0.0361 (7) | 0.0449 (8) | −0.0027 (6) | 0.0124 (6) | 0.0006 (6) |
C5 | 0.0369 (8) | 0.0311 (7) | 0.0464 (8) | 0.0018 (6) | 0.0104 (6) | −0.0028 (6) |
C6 | 0.0459 (9) | 0.0435 (8) | 0.0521 (9) | −0.0045 (7) | 0.0107 (7) | 0.0021 (7) |
C7 | 0.0616 (11) | 0.0576 (11) | 0.0474 (9) | 0.0031 (9) | 0.0071 (8) | 0.0055 (8) |
C8 | 0.0561 (11) | 0.0523 (10) | 0.0555 (10) | 0.0068 (9) | −0.0038 (8) | −0.0108 (8) |
C9 | 0.0457 (9) | 0.0382 (8) | 0.0700 (11) | −0.0023 (7) | 0.0033 (8) | −0.0101 (8) |
C10 | 0.0457 (9) | 0.0332 (7) | 0.0552 (9) | −0.0018 (6) | 0.0119 (7) | −0.0009 (7) |
C11 | 0.0436 (8) | 0.0360 (7) | 0.0396 (7) | −0.0032 (6) | 0.0111 (6) | −0.0018 (6) |
C12 | 0.0748 (14) | 0.0642 (12) | 0.0528 (10) | 0.0207 (10) | −0.0070 (9) | −0.0110 (9) |
C13 | 0.1004 (18) | 0.0631 (13) | 0.0624 (12) | 0.0353 (12) | 0.0069 (12) | 0.0007 (10) |
C14 | 0.0841 (14) | 0.0400 (9) | 0.0607 (11) | −0.0032 (9) | 0.0341 (10) | −0.0072 (8) |
C15 | 0.0679 (13) | 0.0740 (14) | 0.0582 (11) | −0.0013 (11) | 0.0070 (9) | −0.0278 (10) |
C16 | 0.0606 (11) | 0.0658 (12) | 0.0513 (10) | 0.0133 (10) | −0.0021 (8) | −0.0166 (9) |
C17 | 0.0438 (9) | 0.0568 (10) | 0.0531 (9) | 0.0044 (8) | 0.0058 (7) | −0.0069 (8) |
C18 | 0.0518 (11) | 0.0707 (13) | 0.0622 (11) | 0.0164 (9) | 0.0056 (9) | −0.0137 (10) |
C19 | 0.0635 (12) | 0.0582 (11) | 0.0713 (12) | 0.0262 (10) | −0.0057 (10) | −0.0156 (10) |
C20 | 0.0636 (12) | 0.0425 (9) | 0.0630 (11) | 0.0104 (8) | −0.0094 (9) | −0.0011 (8) |
N1 | 0.0424 (7) | 0.0363 (6) | 0.0447 (7) | −0.0045 (5) | 0.0101 (5) | −0.0051 (5) |
O1 | 0.0595 (8) | 0.0514 (7) | 0.0800 (9) | −0.0190 (6) | 0.0296 (7) | −0.0166 (6) |
S1 | 0.0616 (3) | 0.0450 (2) | 0.0554 (3) | −0.0003 (2) | 0.0080 (2) | 0.01415 (18) |
C1—O1 | 1.218 (2) | C10—H10 | 0.9300 |
C1—N1 | 1.370 (2) | C11—C12 | 1.368 (2) |
C1—C2 | 1.490 (2) | C11—C16 | 1.368 (2) |
C2—C17 | 1.396 (2) | C11—N1 | 1.4401 (19) |
C2—C3 | 1.398 (2) | C12—C13 | 1.386 (3) |
C3—C20 | 1.397 (2) | C12—H12 | 0.9300 |
C3—S1 | 1.7587 (19) | C13—C14 | 1.362 (3) |
C4—N1 | 1.4590 (19) | C13—H13 | 0.9300 |
C4—C5 | 1.521 (2) | C14—C15 | 1.356 (3) |
C4—S1 | 1.8211 (16) | C14—H14 | 0.9300 |
C4—H4 | 0.9800 | C15—C16 | 1.382 (3) |
C5—C6 | 1.384 (2) | C15—H15 | 0.9300 |
C5—C10 | 1.393 (2) | C16—H16 | 0.9300 |
C6—C7 | 1.385 (2) | C17—C18 | 1.376 (3) |
C6—H6 | 0.9300 | C17—H17 | 0.9300 |
C7—C8 | 1.382 (3) | C18—C19 | 1.377 (3) |
C7—H7 | 0.9300 | C18—H18 | 0.9300 |
C8—C9 | 1.373 (3) | C19—C20 | 1.378 (3) |
C8—H8 | 0.9300 | C19—H19 | 0.9300 |
C9—C10 | 1.381 (2) | C20—H20 | 0.9300 |
C9—H9 | 0.9300 | ||
O1—C1—N1 | 121.37 (15) | C12—C11—N1 | 120.90 (15) |
O1—C1—C2 | 121.40 (15) | C16—C11—N1 | 119.66 (15) |
N1—C1—C2 | 117.23 (14) | C11—C12—C13 | 119.86 (18) |
C17—C2—C3 | 119.01 (16) | C11—C12—H12 | 120.1 |
C17—C2—C1 | 117.65 (15) | C13—C12—H12 | 120.1 |
C3—C2—C1 | 123.24 (15) | C14—C13—C12 | 120.3 (2) |
C20—C3—C2 | 119.70 (17) | C14—C13—H13 | 119.8 |
C20—C3—S1 | 119.44 (14) | C12—C13—H13 | 119.8 |
C2—C3—S1 | 120.83 (13) | C15—C14—C13 | 119.79 (18) |
N1—C4—C5 | 114.97 (12) | C15—C14—H14 | 120.1 |
N1—C4—S1 | 109.96 (11) | C13—C14—H14 | 120.1 |
C5—C4—S1 | 111.69 (10) | C14—C15—C16 | 120.32 (18) |
N1—C4—H4 | 106.6 | C14—C15—H15 | 119.8 |
C5—C4—H4 | 106.6 | C16—C15—H15 | 119.8 |
S1—C4—H4 | 106.6 | C11—C16—C15 | 120.21 (18) |
C6—C5—C10 | 118.58 (15) | C11—C16—H16 | 119.9 |
C6—C5—C4 | 122.85 (14) | C15—C16—H16 | 119.9 |
C10—C5—C4 | 118.51 (14) | C18—C17—C2 | 120.88 (19) |
C5—C6—C7 | 120.57 (16) | C18—C17—H17 | 119.6 |
C5—C6—H6 | 119.7 | C2—C17—H17 | 119.6 |
C7—C6—H6 | 119.7 | C17—C18—C19 | 119.67 (19) |
C8—C7—C6 | 120.27 (17) | C17—C18—H18 | 120.2 |
C8—C7—H7 | 119.9 | C19—C18—H18 | 120.2 |
C6—C7—H7 | 119.9 | C18—C19—C20 | 120.95 (18) |
C9—C8—C7 | 119.51 (17) | C18—C19—H19 | 119.5 |
C9—C8—H8 | 120.2 | C20—C19—H19 | 119.5 |
C7—C8—H8 | 120.2 | C19—C20—C3 | 119.77 (19) |
C8—C9—C10 | 120.57 (17) | C19—C20—H20 | 120.1 |
C8—C9—H9 | 119.7 | C3—C20—H20 | 120.1 |
C10—C9—H9 | 119.7 | C1—N1—C11 | 119.46 (13) |
C9—C10—C5 | 120.50 (16) | C1—N1—C4 | 122.85 (13) |
C9—C10—H10 | 119.8 | C11—N1—C4 | 117.68 (12) |
C5—C10—H10 | 119.8 | C3—S1—C4 | 95.64 (7) |
C12—C11—C16 | 119.43 (16) | ||
O1—C1—C2—C17 | 18.8 (2) | N1—C11—C16—C15 | −178.59 (18) |
N1—C1—C2—C17 | −161.54 (14) | C14—C15—C16—C11 | −0.6 (3) |
O1—C1—C2—C3 | −157.41 (17) | C3—C2—C17—C18 | 0.1 (3) |
N1—C1—C2—C3 | 22.2 (2) | C1—C2—C17—C18 | −176.35 (16) |
C17—C2—C3—C20 | −0.9 (2) | C2—C17—C18—C19 | 0.9 (3) |
C1—C2—C3—C20 | 175.31 (15) | C17—C18—C19—C20 | −1.0 (3) |
C17—C2—C3—S1 | −178.93 (12) | C18—C19—C20—C3 | 0.2 (3) |
C1—C2—C3—S1 | −2.7 (2) | C2—C3—C20—C19 | 0.8 (3) |
N1—C4—C5—C6 | −1.3 (2) | S1—C3—C20—C19 | 178.82 (14) |
S1—C4—C5—C6 | 124.86 (14) | O1—C1—N1—C11 | 9.4 (2) |
N1—C4—C5—C10 | 175.80 (13) | C2—C1—N1—C11 | −170.25 (13) |
S1—C4—C5—C10 | −58.01 (16) | O1—C1—N1—C4 | −171.62 (16) |
C10—C5—C6—C7 | 0.6 (2) | C2—C1—N1—C4 | 8.8 (2) |
C4—C5—C6—C7 | 177.72 (15) | C12—C11—N1—C1 | −114.62 (19) |
C5—C6—C7—C8 | −0.7 (3) | C16—C11—N1—C1 | 66.1 (2) |
C6—C7—C8—C9 | 0.0 (3) | C12—C11—N1—C4 | 66.3 (2) |
C7—C8—C9—C10 | 0.7 (3) | C16—C11—N1—C4 | −113.00 (18) |
C8—C9—C10—C5 | −0.7 (3) | C5—C4—N1—C1 | 75.41 (18) |
C6—C5—C10—C9 | 0.1 (2) | S1—C4—N1—C1 | −51.67 (17) |
C4—C5—C10—C9 | −177.16 (14) | C5—C4—N1—C11 | −105.55 (15) |
C16—C11—C12—C13 | −1.6 (3) | S1—C4—N1—C11 | 127.37 (12) |
N1—C11—C12—C13 | 179.11 (19) | C20—C3—S1—C4 | 148.70 (14) |
C11—C12—C13—C14 | −0.4 (4) | C2—C3—S1—C4 | −33.26 (15) |
C12—C13—C14—C15 | 1.8 (4) | N1—C4—S1—C3 | 56.83 (12) |
C13—C14—C15—C16 | −1.3 (3) | C5—C4—S1—C3 | −72.06 (12) |
C12—C11—C16—C15 | 2.1 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
C10—H10···O1i | 0.93 | 2.82 | 3.422 (2) | 124 |
C15—H15···O1ii | 0.93 | 2.69 | 3.477 (2) | 142 |
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) −x, −y, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C10—H10···O1i | 0.93 | 2.82 | 3.422 (2) | 123.6 |
C15—H15···O1ii | 0.93 | 2.69 | 3.477 (2) | 142.4 |
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) −x, −y, −z. |
Acknowledgements
We acknowledge NSF funding (CHEM-0131112) for the X-ray diffractometer, and are thankful to Dr John Tierney for intellectual contributions and to Euticals Inc. for the gift of T3P in 2-methyltetrahydrofuran. RVB, DJC, and ASC acknowledge summer internship support from SP Controls Inc.
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We report here the crystal structure (Fig. 1) of the title compound, which has two phenyl rings connected to the central thiazine ring and a third phenyl ring fused to the thiazine ring. We have recently reported the synthesis and crystal structures of three related compounds: (i) 2-(3-nitrophenyl)-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one (Yennawar, Silverberg, Minehan and Tierney, 2013) (ii) 2,3-diphenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one (Yennawar & Silverberg, 2014) and (iii) 6,7-diphenyl-5-thia-7-azaspiro[2.6]nonan-8-one (Yennawar & Silverberg, 2013). In order to more directly compare the structure of the benzothiazinone ring to the thiazinone and thiazepanone, we have obtained the crystal structure of the title compound, which, like the latter two compounds does not have a substituent on the C-phenyl ring. In the present structure, the dihedral angle between the phenyl rings is 74.25 (6)° - almost perpendicular and within the range of 60–90° in the three other compounds we have reported (see above). The thiazine ring has an envelope conformation with the 2-carbon forming the flap. In the crystal packing (Fig 2), molecules are linked by weak C—H···O interactions (Table 1).
The title compound has been synthesized previously (Ponci et al., 1963; Kollenz & Ziegler, 1970; Oae & Numata, 1974; Badea et al., 1998), but not by condensation of N-benzylideneaniline with thiosalicylic acid. In our hands, this reaction was not successfully accomplished in refluxing toluene or xylenes, with sodium sulfate in dioxane (Kamel et al., 2010), with p-toluenesulfonic acid in refluxing toluene (Zarghi et al., 2009), or with N,N'-dicyclohexylcarbodiimide (DCC) in THF (Zhou et al., 2008; Srivastava et al., 2002). The title molecule was finally synthesized by condensation in the presence of 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphorinane-2,4,6-trioxide (T3P) and pyridine, as per our previous reports.