organic compounds
N-[(2Z,4Z)-4-Benzylidene-6-chloro-1,4-dihydropyrido[2,3-d][1,3]thiazin-2-ylidene]benzamide
aMolecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, PO Wits 2050, South Africa
*Correspondence e-mail: demetrius.levendis@wits.ac.za
In the 21H14ClN3OS, molecules assemble into inversion dimers via pairs of N—H⋯N hydrogen bonds involving the N—H hydrogen of the thiazine ring and the N atom of the pyridine ring. There is a close intramolecular contact [2.570 (2) Å] between the carbonyl O atom of the benzamide and the S atom of the puckered thiazine ring. The title compound can exist in two tautomeric forms, viz. amino or imino. The observed structure is compatible with the imino form on the basis of observed residual electron density and the two C—N bond lengths of 1.308 (2) and 1.353 (2) Å.
of the title compound, CRelated literature
For the synthesis of related heterocycles, see: Fernandes & Reid (2003); Schmittel et al. (2004); Sonogashira et al. (1975). For related thiazine structures, see: Cohen-Addad et al. (1981); Bernalte-Garcia et al. (2004); Kalman et al. (1987); Peng & Wu (2009); Palsuledesai et al. (2009).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: APEX2 (Bruker, 2005); cell SAINT-Plus (Bruker, 2005); data reduction: SAINT-Plus and XPREP (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009), Mercury (Macrae et al., 2008) and SCHAKAL99 (Keller, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536812029741/nk2159sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812029741/nk2159Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812029741/nk2159Isup3.cml
The title compound (1a) was obtained by the reaction sequence:
2-amino-5-chloro-3-iodopyridine → (2) → (3) → (1).
For the preparation of 2-amino-5-chloro-3-phenylethynylpyridine, (2), phenylacetylene (6.0 ml, 54.6 mmol) was added to a stirred mixture of 2-amino-5-chloro-3-iodopyridine (12.72 g, 50 mmol), CuI (190 mg, 1 mmol) and (Ph3P)2PdCl2 (702 mg, 1 mmol) in Et3N (300 ml) under N2. After 24 h, the mixture was diluted with ether (300 ml) and filtered. Ether and Et3N were removed from the filtrate and the residual solid was dissolved in ether. The resulting solution was washed with water, dried, and solvent was removed. The residual solid was purified by
on silica (CH2Cl2) to give (2) (9.72 g, 85%) as pale yellow crystals (m.p. 383-388 K).For the preparation of N-nenzoyl-N'-(5-chloro-3-phenylethynylpyridyl-2)thiourea, (3), benzoylisothioisocyanate (0.74 ml, 5.5 mmol) was added to a solution of (2) (1.14 g, 5 mmol) in CH2Cl2 (10 ml) and the solution was kept at ambient temperature for 24 h. Hexane was added to complete the crystallisation that had partially taken place. The resulting solid was collected and purified by
on silica (CH2Cl2), giving (3) (1.56 g, 79.6%) as lemon yellow crystals (m.p. 430-433 K).For the preparation of N-[(2Z,4Z)-4-benzylidene-6-chloro-1,4-dihydropyrido[2,3-\ d][1,3]thiazin-2-ylidene]benzamide, (1), DBU (0.75 ml, 5 mmol) was added to a solution of (3) (784 mg, 2 mmol) in THF (10 ml). After 24 h the solid was chromatographed on silica (CH2Cl2 then 2% (V/V) EtOH in CH2Cl2). Solvent was removed from the eluates and the residual solid was recrystallized (DMF/MeCN) to give (1a) (631 mg, 80.5%; m.p. 502-504 K).
One N-bound H atom on the thiazine ring was placed according to the observed electron density and allowed to refine freely. The remaining H atoms were positioned geometrically and allowed to ride on their respective parent atoms, with C—H bond lengths of 1.00 (methine) and 0.99 Å (methylene CH2) and with Uiso(H) = 1.2 times Ueq(C). Phenyl atoms C21 and C22 were reported by PLATON to have slightly distorted atomic displacement (ADP) parameters. As a consequence, DELU and SIMU were used in the final refinements on the two atoms to restrain their ADPs to more reasonable values.
The potential biological activity of 1,2-, 1,4-, 2,1- and 3,1 benzothiazines has stimulated the development of new syntheses of compounds based on these systems. Thus we (Fernandes & Reid, 2003) and other workers (Schmittel et al., 2004) have invented new syntheses of (4Z)-4-methylene-4H-3,1-benzothiazines. In furtherance of our studies we have applied the principle of our synthesis to the preparation of pyridine analogues of 4-methylene-4H-3,1-benzothiazines, namely 4-methylene-1,4-dihydropyrido[2,3-d] thiazines. Thus 2-amino-5-chloro-3-phenylethynylpyridine (2, Fig. 1), obtained by the Sonogashira reaction (Sonogashira et al., 1975) of 2-amino-5-chloro-3-iodopyridine with phenylacetylene, reacted with benzoylisothiocyanate to give the thiourea (3, Fig. 1), which was cyclized with DBU to give the title compound. The structure of 1a has not been reported previously and is reported here (Fig. 2) as a part of an ongoing study of this class of 1,3-thiazines.
The title compound can possibly exist in two tautomeric forms, 1a and 1 b (Fig. 1). In the structure investigated in this work, residual electron density was observed about 0.85 Å from N(2), with no significant residual electron density near N(1), indicating that we have crystallized the imino form (1a). The C—N bond distances are also compatible with the imino form in which the C(8)—N(1) and C(8)—N(2) distances are 1.308 (2) and 1.353 (2) Å respectively. This is in agreement with a neutron diffraction study of the related 2-(2-chlorobenzoylimino)-1,3-thiazolidine (Cohen-Addad et al., 1981). The intramolecular contact of 2.57 (2) Å between the carbonyl oxygen O(1) and S(1) is typical for imino thiazolidines (see for example Palsuledesai et al., 2009). The molecules assemble via weak N—H···N hydrogen bonds into inversion dimers using the N—H hydrogen atom of the thiazine ring and the N of the pyridine group, with an N···N distance of 2.973 (1) Å. The packing of the hydrogen bonded dimers is shown in Fig. 3. Significant π–π interactions occur between the pyridine ring (N(3), C(2)—C(4)) at (x,y,z)) and the benzoyl ring (C10)-(15)) at either (x - 1, y - 1, z) or (x, y - 1, z)) with Cg···Cg distances of 3.651 (1) and 3.646 (1) Å respectively. This results in a stack of alternating pyridine and benzoyl rings interacting through π–π interactions along the a axis (Fig. 4).
For the synthesis of related heterocycles, see: Fernandes & Reid (2003); Schmittel et al. (2004); Sonogashira et al. (1975). For related thiazine structures, see: Cohen-Addad et al. (1981); Bernalte-Garcia et al. (2004); Kalman et al. (1987); Peng & Wu (2009); Palsuledesai et al. (2009).
Data collection: APEX2 (Bruker, 2005); cell
SAINT-Plus (Bruker, 2005); data reduction: SAINT-Plus and XPREP (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009), Mercury (Macrae et al., 2008) and SCHAKAL99 (Keller, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).C21H14ClN3OS | Z = 2 |
Mr = 391.86 | F(000) = 404 |
Triclinic, P1 | Dx = 1.458 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.2372 (2) Å | Cell parameters from 6485 reflections |
b = 8.3977 (3) Å | θ = 3.8–27° |
c = 15.7467 (6) Å | µ = 0.35 mm−1 |
α = 101.227 (2)° | T = 173 K |
β = 98.427 (2)° | Block, colourless |
γ = 103.768 (1)° | 0.37 × 0.28 × 0.19 mm |
V = 892.85 (5) Å3 |
Bruker SMART APEXII CCD area-detector diffractometer | Rint = 0.029 |
ω scans | θmax = 27°, θmin = 1.4° |
18107 measured reflections | h = −8→9 |
3894 independent reflections | k = −10→10 |
3538 reflections with I > 2σ(I) | l = −20→20 |
Refinement on F2 | 7 restraints |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.028 | w = 1/[σ2(Fo2) + (0.0401P)2 + 0.2776P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.077 | (Δ/σ)max = 0.001 |
S = 1.05 | Δρmax = 0.27 e Å−3 |
3894 reflections | Δρmin = −0.21 e Å−3 |
248 parameters |
C21H14ClN3OS | γ = 103.768 (1)° |
Mr = 391.86 | V = 892.85 (5) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.2372 (2) Å | Mo Kα radiation |
b = 8.3977 (3) Å | µ = 0.35 mm−1 |
c = 15.7467 (6) Å | T = 173 K |
α = 101.227 (2)° | 0.37 × 0.28 × 0.19 mm |
β = 98.427 (2)° |
Bruker SMART APEXII CCD area-detector diffractometer | 3538 reflections with I > 2σ(I) |
18107 measured reflections | Rint = 0.029 |
3894 independent reflections |
R[F2 > 2σ(F2)] = 0.028 | 7 restraints |
wR(F2) = 0.077 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.27 e Å−3 |
3894 reflections | Δρmin = −0.21 e Å−3 |
248 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. |
x | y | z | Uiso*/Ueq | ||
C2 | −0.06525 (16) | −0.02208 (14) | 0.13025 (7) | 0.0204 (2) | |
C4 | −0.22472 (17) | −0.29516 (15) | 0.05686 (8) | 0.0240 (2) | |
H4 | −0.272 | −0.3801 | 0.0033 | 0.029* | |
C5 | −0.25381 (17) | −0.33684 (15) | 0.13550 (8) | 0.0231 (2) | |
C6 | −0.18282 (17) | −0.21689 (15) | 0.21447 (8) | 0.0231 (2) | |
H6 | −0.2028 | −0.2443 | 0.2688 | 0.028* | |
C7 | −0.08154 (16) | −0.05529 (14) | 0.21279 (7) | 0.0207 (2) | |
C8 | 0.06508 (16) | 0.28693 (14) | 0.18128 (7) | 0.0208 (2) | |
C9 | 0.16648 (17) | 0.57853 (15) | 0.21226 (8) | 0.0230 (2) | |
C10 | 0.27176 (17) | 0.72581 (15) | 0.18204 (8) | 0.0250 (3) | |
C11 | 0.37511 (19) | 0.87229 (16) | 0.24628 (10) | 0.0327 (3) | |
H11 | 0.3827 | 0.8737 | 0.3072 | 0.039* | |
C12 | 0.4664 (2) | 1.01543 (18) | 0.22140 (12) | 0.0429 (4) | |
H12 | 0.5375 | 1.1147 | 0.2651 | 0.051* | |
C13 | 0.4540 (2) | 1.01364 (18) | 0.13303 (13) | 0.0468 (4) | |
H13 | 0.5156 | 1.1123 | 0.1161 | 0.056* | |
C14 | 0.3525 (2) | 0.86926 (19) | 0.06890 (11) | 0.0412 (4) | |
H14 | 0.3446 | 0.8692 | 0.0081 | 0.049* | |
C15 | 0.2619 (2) | 0.72417 (17) | 0.09306 (9) | 0.0301 (3) | |
H15 | 0.1937 | 0.6245 | 0.049 | 0.036* | |
C16 | 0.01362 (18) | 0.07578 (14) | 0.29392 (8) | 0.0229 (2) | |
C17 | 0.0849 (2) | 0.04176 (16) | 0.36959 (8) | 0.0285 (3) | |
H17 | 0.0677 | −0.0736 | 0.3706 | 0.034* | |
C18 | 0.1887 (2) | 0.17028 (16) | 0.45202 (8) | 0.0320 (3) | |
C19 | 0.3837 (3) | 0.1862 (2) | 0.48353 (10) | 0.0463 (4) | |
H19 | 0.4457 | 0.1111 | 0.4536 | 0.056* | |
C20 | 0.4890 (3) | 0.3102 (2) | 0.55806 (11) | 0.0557 (5) | |
H20 | 0.623 | 0.3217 | 0.5779 | 0.067* | |
C21 | 0.3987 (3) | 0.4163 (2) | 0.60314 (10) | 0.0548 (5) | |
H21 | 0.4702 | 0.501 | 0.6543 | 0.066* | |
C22 | 0.2053 (3) | 0.3997 (2) | 0.57427 (10) | 0.0545 (5) | |
H22 | 0.1429 | 0.4718 | 0.6063 | 0.065* | |
C23 | 0.0990 (3) | 0.27748 (19) | 0.49810 (10) | 0.0427 (4) | |
H23 | −0.0344 | 0.268 | 0.478 | 0.051* | |
N1 | 0.12656 (14) | 0.42335 (12) | 0.15357 (6) | 0.0230 (2) | |
N2 | 0.02664 (15) | 0.13768 (12) | 0.12157 (7) | 0.0225 (2) | |
H2 | 0.052 (2) | 0.144 (2) | 0.0713 (11) | 0.032 (4)* | |
N3 | −0.13207 (14) | −0.13887 (12) | 0.05389 (6) | 0.0224 (2) | |
Cl1 | −0.37769 (5) | −0.54060 (4) | 0.13535 (2) | 0.03250 (10) | |
S1 | 0.03383 (5) | 0.28939 (4) | 0.290500 (18) | 0.02461 (9) | |
O1 | 0.11843 (14) | 0.60154 (11) | 0.28445 (6) | 0.0292 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C2 | 0.0209 (5) | 0.0187 (5) | 0.0225 (5) | 0.0056 (4) | 0.0058 (4) | 0.0062 (4) |
C4 | 0.0236 (6) | 0.0208 (6) | 0.0242 (6) | 0.0031 (4) | 0.0016 (4) | 0.0038 (5) |
C5 | 0.0208 (5) | 0.0179 (5) | 0.0299 (6) | 0.0026 (4) | 0.0041 (4) | 0.0082 (5) |
C6 | 0.0252 (6) | 0.0217 (6) | 0.0250 (6) | 0.0068 (5) | 0.0068 (5) | 0.0097 (5) |
C7 | 0.0230 (5) | 0.0189 (5) | 0.0222 (5) | 0.0072 (4) | 0.0059 (4) | 0.0067 (4) |
C8 | 0.0217 (5) | 0.0204 (5) | 0.0214 (5) | 0.0060 (4) | 0.0054 (4) | 0.0065 (4) |
C9 | 0.0232 (6) | 0.0203 (6) | 0.0267 (6) | 0.0066 (4) | 0.0041 (4) | 0.0083 (5) |
C10 | 0.0237 (6) | 0.0192 (6) | 0.0358 (7) | 0.0080 (5) | 0.0104 (5) | 0.0096 (5) |
C11 | 0.0303 (7) | 0.0219 (6) | 0.0445 (8) | 0.0052 (5) | 0.0103 (6) | 0.0056 (5) |
C12 | 0.0358 (8) | 0.0208 (6) | 0.0703 (11) | 0.0031 (6) | 0.0198 (7) | 0.0058 (7) |
C13 | 0.0487 (9) | 0.0244 (7) | 0.0817 (12) | 0.0115 (6) | 0.0383 (9) | 0.0255 (8) |
C14 | 0.0520 (9) | 0.0335 (8) | 0.0541 (9) | 0.0186 (7) | 0.0295 (7) | 0.0255 (7) |
C15 | 0.0343 (7) | 0.0246 (6) | 0.0386 (7) | 0.0114 (5) | 0.0153 (6) | 0.0142 (5) |
C16 | 0.0294 (6) | 0.0184 (5) | 0.0225 (5) | 0.0064 (5) | 0.0085 (5) | 0.0066 (4) |
C17 | 0.0411 (7) | 0.0215 (6) | 0.0241 (6) | 0.0085 (5) | 0.0069 (5) | 0.0078 (5) |
C18 | 0.0530 (8) | 0.0248 (6) | 0.0194 (6) | 0.0100 (6) | 0.0064 (5) | 0.0095 (5) |
C19 | 0.0594 (10) | 0.0467 (9) | 0.0287 (7) | 0.0188 (8) | −0.0033 (7) | 0.0032 (6) |
C20 | 0.0656 (11) | 0.0570 (11) | 0.0324 (8) | 0.0097 (9) | −0.0085 (8) | 0.0047 (8) |
C21 | 0.0885 (14) | 0.0394 (9) | 0.0233 (7) | 0.0007 (9) | 0.0015 (8) | 0.0049 (6) |
C22 | 0.0980 (15) | 0.0359 (8) | 0.0330 (8) | 0.0197 (9) | 0.0264 (9) | 0.0047 (7) |
C23 | 0.0629 (10) | 0.0373 (8) | 0.0313 (7) | 0.0159 (7) | 0.0163 (7) | 0.0086 (6) |
N1 | 0.0261 (5) | 0.0188 (5) | 0.0246 (5) | 0.0043 (4) | 0.0069 (4) | 0.0074 (4) |
N2 | 0.0304 (5) | 0.0184 (5) | 0.0191 (5) | 0.0043 (4) | 0.0083 (4) | 0.0062 (4) |
N3 | 0.0246 (5) | 0.0202 (5) | 0.0214 (5) | 0.0042 (4) | 0.0041 (4) | 0.0054 (4) |
Cl1 | 0.03448 (18) | 0.02067 (15) | 0.03662 (18) | −0.00357 (12) | 0.00425 (13) | 0.00945 (13) |
S1 | 0.03781 (18) | 0.01751 (15) | 0.02036 (15) | 0.00759 (12) | 0.00947 (12) | 0.00618 (11) |
O1 | 0.0408 (5) | 0.0218 (4) | 0.0268 (4) | 0.0083 (4) | 0.0106 (4) | 0.0074 (4) |
C2—N3 | 1.3365 (15) | C12—H12 | 0.95 |
C2—N2 | 1.3908 (15) | C13—C14 | 1.383 (2) |
C2—C7 | 1.3968 (16) | C13—H13 | 0.95 |
C4—N3 | 1.3374 (15) | C14—C15 | 1.3901 (18) |
C4—C5 | 1.3822 (17) | C14—H14 | 0.95 |
C4—H4 | 0.95 | C15—H15 | 0.95 |
C5—C6 | 1.3797 (17) | C16—C17 | 1.3379 (17) |
C5—Cl1 | 1.7319 (12) | C16—S1 | 1.7768 (12) |
C6—C7 | 1.3877 (16) | C17—C18 | 1.4821 (18) |
C6—H6 | 0.95 | C17—H17 | 0.95 |
C7—C16 | 1.4669 (16) | C18—C23 | 1.386 (2) |
C8—N1 | 1.3075 (15) | C18—C19 | 1.391 (2) |
C8—N2 | 1.3531 (15) | C19—C20 | 1.388 (2) |
C8—S1 | 1.7641 (12) | C19—H19 | 0.95 |
C9—O1 | 1.2300 (15) | C20—C21 | 1.375 (3) |
C9—N1 | 1.3818 (15) | C20—H20 | 0.95 |
C9—C10 | 1.4912 (16) | C21—C22 | 1.371 (3) |
C10—C15 | 1.3896 (18) | C21—H21 | 0.95 |
C10—C11 | 1.3970 (18) | C22—C23 | 1.399 (2) |
C11—C12 | 1.384 (2) | C22—H22 | 0.95 |
C11—H11 | 0.95 | C23—H23 | 0.95 |
C12—C13 | 1.378 (3) | N2—H2 | 0.847 (16) |
N3—C2—N2 | 114.40 (10) | C15—C14—H14 | 119.9 |
N3—C2—C7 | 123.77 (10) | C10—C15—C14 | 119.61 (13) |
N2—C2—C7 | 121.83 (10) | C10—C15—H15 | 120.2 |
N3—C4—C5 | 122.00 (11) | C14—C15—H15 | 120.2 |
N3—C4—H4 | 119 | C17—C16—C7 | 123.17 (11) |
C5—C4—H4 | 119 | C17—C16—S1 | 118.99 (9) |
C6—C5—C4 | 120.21 (11) | C7—C16—S1 | 117.84 (8) |
C6—C5—Cl1 | 119.72 (9) | C16—C17—C18 | 124.98 (11) |
C4—C5—Cl1 | 120.07 (9) | C16—C17—H17 | 117.5 |
C5—C6—C7 | 118.52 (11) | C18—C17—H17 | 117.5 |
C5—C6—H6 | 120.7 | C23—C18—C19 | 118.71 (14) |
C7—C6—H6 | 120.7 | C23—C18—C17 | 122.21 (14) |
C6—C7—C2 | 117.58 (10) | C19—C18—C17 | 119.07 (13) |
C6—C7—C16 | 122.17 (10) | C20—C19—C18 | 120.99 (16) |
C2—C7—C16 | 120.20 (10) | C20—C19—H19 | 119.5 |
N1—C8—N2 | 116.67 (10) | C18—C19—H19 | 119.5 |
N1—C8—S1 | 123.60 (9) | C21—C20—C19 | 119.80 (18) |
N2—C8—S1 | 119.73 (9) | C21—C20—H20 | 120.1 |
O1—C9—N1 | 124.89 (11) | C19—C20—H20 | 120.1 |
O1—C9—C10 | 119.63 (11) | C22—C21—C20 | 120.00 (15) |
N1—C9—C10 | 115.47 (10) | C22—C21—H21 | 120 |
C15—C10—C11 | 119.70 (12) | C20—C21—H21 | 120 |
C15—C10—C9 | 122.27 (11) | C21—C22—C23 | 120.59 (16) |
C11—C10—C9 | 117.95 (11) | C21—C22—H22 | 119.7 |
C12—C11—C10 | 120.15 (14) | C23—C22—H22 | 119.7 |
C12—C11—H11 | 119.9 | C18—C23—C22 | 119.87 (17) |
C10—C11—H11 | 119.9 | C18—C23—H23 | 120.1 |
C13—C12—C11 | 119.86 (14) | C22—C23—H23 | 120.1 |
C13—C12—H12 | 120.1 | C8—N1—C9 | 118.58 (10) |
C11—C12—H12 | 120.1 | C8—N2—C2 | 127.76 (10) |
C12—C13—C14 | 120.48 (13) | C8—N2—H2 | 115.3 (11) |
C12—C13—H13 | 119.8 | C2—N2—H2 | 116.6 (11) |
C14—C13—H13 | 119.8 | C2—N3—C4 | 117.83 (10) |
C13—C14—C15 | 120.19 (14) | C8—S1—C16 | 101.63 (5) |
C13—C14—H14 | 119.9 | ||
N3—C4—C5—C6 | −1.49 (19) | S1—C16—C17—C18 | −2.56 (19) |
N3—C4—C5—Cl1 | 179.12 (9) | C16—C17—C18—C23 | 64.2 (2) |
C4—C5—C6—C7 | −0.37 (18) | C16—C17—C18—C19 | −114.62 (16) |
Cl1—C5—C6—C7 | 179.02 (9) | C23—C18—C19—C20 | −2.0 (2) |
C5—C6—C7—C2 | 2.81 (17) | C17—C18—C19—C20 | 176.88 (15) |
C5—C6—C7—C16 | −174.49 (11) | C18—C19—C20—C21 | 1.8 (3) |
N3—C2—C7—C6 | −3.79 (17) | C19—C20—C21—C22 | −0.2 (3) |
N2—C2—C7—C6 | 177.37 (11) | C20—C21—C22—C23 | −1.2 (3) |
N3—C2—C7—C16 | 173.57 (11) | C19—C18—C23—C22 | 0.6 (2) |
N2—C2—C7—C16 | −5.27 (17) | C17—C18—C23—C22 | −178.26 (13) |
O1—C9—C10—C15 | −153.18 (12) | C21—C22—C23—C18 | 1.0 (2) |
N1—C9—C10—C15 | 25.39 (17) | N2—C8—N1—C9 | 179.63 (10) |
O1—C9—C10—C11 | 23.54 (17) | S1—C8—N1—C9 | −1.12 (16) |
N1—C9—C10—C11 | −157.89 (11) | O1—C9—N1—C8 | −13.03 (18) |
C15—C10—C11—C12 | 0.3 (2) | C10—C9—N1—C8 | 168.49 (10) |
C9—C10—C11—C12 | −176.46 (12) | N1—C8—N2—C2 | −170.01 (11) |
C10—C11—C12—C13 | 0.5 (2) | S1—C8—N2—C2 | 10.70 (17) |
C11—C12—C13—C14 | −0.6 (2) | N3—C2—N2—C8 | 162.12 (11) |
C12—C13—C14—C15 | 0.0 (2) | C7—C2—N2—C8 | −18.93 (19) |
C11—C10—C15—C14 | −1.03 (19) | N2—C2—N3—C4 | −179.06 (10) |
C9—C10—C15—C14 | 175.64 (12) | C7—C2—N3—C4 | 2.02 (17) |
C13—C14—C15—C10 | 0.9 (2) | C5—C4—N3—C2 | 0.68 (17) |
C6—C7—C16—C17 | 29.87 (19) | N1—C8—S1—C16 | −165.12 (10) |
C2—C7—C16—C17 | −147.36 (13) | N2—C8—S1—C16 | 14.12 (11) |
C6—C7—C16—S1 | −150.07 (10) | C17—C16—S1—C8 | 146.10 (11) |
C2—C7—C16—S1 | 32.70 (15) | C7—C16—S1—C8 | −33.96 (10) |
C7—C16—C17—C18 | 177.51 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···N3i | 0.847 (16) | 2.131 (17) | 2.9733 (14) | 173.1 (15) |
Symmetry code: (i) −x, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | C21H14ClN3OS |
Mr | 391.86 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 173 |
a, b, c (Å) | 7.2372 (2), 8.3977 (3), 15.7467 (6) |
α, β, γ (°) | 101.227 (2), 98.427 (2), 103.768 (1) |
V (Å3) | 892.85 (5) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.35 |
Crystal size (mm) | 0.37 × 0.28 × 0.19 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 18107, 3894, 3538 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.639 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.077, 1.05 |
No. of reflections | 3894 |
No. of parameters | 248 |
No. of restraints | 7 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.27, −0.21 |
Computer programs: APEX2 (Bruker, 2005), SAINT-Plus (Bruker, 2005), SAINT-Plus and XPREP (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009), Mercury (Macrae et al., 2008) and SCHAKAL99 (Keller, 1999), WinGX (Farrugia, 1999) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···N3i | 0.847 (16) | 2.131 (17) | 2.9733 (14) | 173.1 (15) |
Symmetry code: (i) −x, −y, −z. |
Acknowledgements
The University of the Witwatersrand and the Molecular Sciences Institute are acknowledged for providing the infrastructure required for this work.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The potential biological activity of 1,2-, 1,4-, 2,1- and 3,1 benzothiazines has stimulated the development of new syntheses of compounds based on these systems. Thus we (Fernandes & Reid, 2003) and other workers (Schmittel et al., 2004) have invented new syntheses of (4Z)-4-methylene-4H-3,1-benzothiazines. In furtherance of our studies we have applied the principle of our synthesis to the preparation of pyridine analogues of 4-methylene-4H-3,1-benzothiazines, namely 4-methylene-1,4-dihydropyrido[2,3-d] thiazines. Thus 2-amino-5-chloro-3-phenylethynylpyridine (2, Fig. 1), obtained by the Sonogashira reaction (Sonogashira et al., 1975) of 2-amino-5-chloro-3-iodopyridine with phenylacetylene, reacted with benzoylisothiocyanate to give the thiourea (3, Fig. 1), which was cyclized with DBU to give the title compound. The structure of 1a has not been reported previously and is reported here (Fig. 2) as a part of an ongoing study of this class of 1,3-thiazines.
The title compound can possibly exist in two tautomeric forms, 1a and 1 b (Fig. 1). In the structure investigated in this work, residual electron density was observed about 0.85 Å from N(2), with no significant residual electron density near N(1), indicating that we have crystallized the imino form (1a). The C—N bond distances are also compatible with the imino form in which the C(8)—N(1) and C(8)—N(2) distances are 1.308 (2) and 1.353 (2) Å respectively. This is in agreement with a neutron diffraction study of the related 2-(2-chlorobenzoylimino)-1,3-thiazolidine (Cohen-Addad et al., 1981). The intramolecular contact of 2.57 (2) Å between the carbonyl oxygen O(1) and S(1) is typical for imino thiazolidines (see for example Palsuledesai et al., 2009). The molecules assemble via weak N—H···N hydrogen bonds into inversion dimers using the N—H hydrogen atom of the thiazine ring and the N of the pyridine group, with an N···N distance of 2.973 (1) Å. The packing of the hydrogen bonded dimers is shown in Fig. 3. Significant π–π interactions occur between the pyridine ring (N(3), C(2)—C(4)) at (x,y,z)) and the benzoyl ring (C10)-(15)) at either (x - 1, y - 1, z) or (x, y - 1, z)) with Cg···Cg distances of 3.651 (1) and 3.646 (1) Å respectively. This results in a stack of alternating pyridine and benzoyl rings interacting through π–π interactions along the a axis (Fig. 4).