Synthesis and E/Z configuration determination of novel derivatives of 3-Aryl-2-(benzothiazol-2-ylthio) acrylonitrile, 3-(benzothiazol-2- ylthio)-4-(furan-2-yl)-3-buten-2-one and 2-(1-(Furan-2-yl)-3-oxobut-1-en-2-ylthio)-3-phenylquinazolin- 4(3H)-one

Abstract

Knoevenagel condensation of 2-(benzothiazol-2-ylthio) acetonitrile (2) with either furan-2-carbaldehyde or thiophene-2-carbaldehydes leads to E-isomers 4a–b exclusively, while the condensation of the compound 2 with benzaldehyde or para-substituted benzaldehydes with an electron-donating group afforded E/Z mixtures 4c–e with preferentially formation of the E-isomer. Condensation of furan-2-carbaldehyde (3a) with either 1-(benzothiazol-2'-ylthio) propan-2-one (5) or 2-(2'-oxo propylthio)-3-phenyl-quinazolin-4(3H)-one (9) leads exclusively to the Z-isomers of 6 and 10, respectively. The structures of the newly synthesized compounds were elucidated by elemental analyses, 1H-NMR and 13C-NMR spectra, COSY, HSQC, HMBC, NOE, MS and X-ray crystallographic investigations.