SYNTHESIS OF 4,7(2H)-DIHYDROTHIAZOLO[3,2-A]PYRIDINES FROM 3-CARBAMOYL-1,4-DIHYDROPYRIDINE-2(3H)-THIONES

gamma-Dicyanobutyrothioamide (3) under bar, 3-carbamoyl substituted 1, 4-dihydropyridine-2-thiolates (5) under bar, 3,4-dihydropyridine-2-thi olates (6) under bar and 1,4-dihydropyridine2(3H)-thiones have been sy nthesized by Michael condensation of benzylidenemalononitrile (1) unde r bar with thiocarbamoylacetamides (2) under bar. Use of stronger base s and elevated temperature is favourable for 3,4-dihydroisomers (6) un der bar. The influence of the modification of the electrophilic yliden e component on the course of the subsequent intramolecular cyclization of Michael adducts of type (3) under bar has been evaluated. The conv enient method of synthesis of 4,7-(2H)dihydrothiazolo[3,2-a]pyridines <(10)under bar> has been elaborated by alkylation of thiones (7) under bar with the subsequent smooth intramolecular N-acylation of the poss ible intermediates-1,4-dihydropyridines (9) under bar containing 2-cya nomethylthio group.