Crystal structure of (2Z,5Z)-3-allyl-5-(4-(methylthio)benzylidene)- 2-(p-tolylimino)thiazolidin-4-one, C21H20N2OS2

Abstract

Source of materialTo as olution of 3-allyl-2-(p-tolylimino)thiazolidin-4-one (3 mmol) and base supported ionic liquid-like phase (SILLP) (0.5 g) in ethanol (20 mL), 4-methylthiobenzaldehyde (3 mmol) was added and the mixture was heated at reflux for 3h.S ILLP was separated by filtration. Then the solution was concentrated in vacuum and kept at -15 ºC over 2h.The residue was filtered off and recrystallized from methanol to give 3-allyl-5-(4-(methylthio)benzylidene)-2-(p-tolylimino)thiazolidin-4-one as ayellow solid in 87 %yield (m.p. =138-140°C). Elemental analysisfound: C, 66.13 %; H, 5.35 %; N, 7.47 %; calculated for C 21 H 20 N 2 OS 2 :C,66.28 %; H, 5.30 %; N, 7.36 %. Melting points were measured on aElectrothermal 9100 instrument and are uncorrected. Elemental analyses were made by aC arlo-Erba EA1110CNNO-S analyzer. Experimental detailsAll hydrogen atomswere refined in isotropic approximation in a riding model with U iso (H) =1 .2 U eq (C). The structure was checked with PLATON [1] and no solvent accesible void was found. The residual densities are 0.32 eÅ -3 (highest peak at 1.24 Åfrom C13) and -0.21 eÅ -3 (deepest hole at 0.61 Åfrom H12). DiscussionThiazolidinone moiety is an important structure element in medicinal chemistry [2][3][4][5][6] and substituted thiazolidinones show a broad spectrum of biological activities [7][8][9][10][11] [16].Therefore, facile preparation of various 5-arylidene thiazolidinones is highly desirable. In continuation of our ongoing interests in the development of benign methods targeted at the synthesis of biologically important heterocycles [17][18][19], we used base supported ionic liquid-like phase (SILLP) [20] as an efficientand recyclablesolid phasecatalystinthe synthesis of thetitle compound. The X-ray diffractometric analysis of the title product was carried out on the single crystal prepared in peteroleum ether/EtOAc(4:1). The packing in the title crystal structure can be described as asuccessionofparallel layers.The conjugationbetween C=Oand the amiden itrogeni se vident from thev alue of theb ondl ength d(Nl-C10) =1.362(5)Å.The thiazole ring is planar as indicated by torsion angles ÐC9-C10-N1-C14 =-3.4(5)°, ÐN1-C10-C9-S2 =0.4(4)°, ÐC10-C9-S2-C14 =1.8(3)°and ÐN1-C14-S2-C9 =-36(3)°. In addition, the torsion angles ÐS2-C14-N2-C15 =0 .8(6)°, ÐO1-C10-N1-C11 =1 .2(6)°, ÐN2-C14-N1-C11 =1.8(6)°, ÐC5-C8-C9-S2 =-1.0(7)°and ÐN1-C10-C9-S2 =0 .4(4)°revealed that the thiazole ring is coplanar with O1, N2,C 5, C8,C 11 and C15.T he distances.362(5) Åagree with the literature reports [21][22][23][24][25]. The bond length d(C14-N2) =1.259(5) Åand the angles ÐN2-C14-S2 =128.2(3)°and ÐN2-C14-N1 =121.8(4)°con-firm the imine nature of the N2-C14 bond. The distance d(C8-C9)=1.331(5) Åand the angles ÐC8-C9-S2 =129.7(3)°a nd ÐC8-C9-C10 =120.5(3)°are consistant with double bond features of C8-C9.This analysis also unambiguously confirmed the Z configuration at the chiral axis and this is quite evident from the spatial orientation of arylg roups attached to C14-N2 and C8-C9 double bonds.