One-pot synthesis of pyridines, thienopyridines, pyrrolothienopyridines and (1,8)naphthyridines under phase-transfer catalysis conditions

A new series of pyridines 2(a,b), (1,8)naphthyridines 3(a,b) and diazepines 4(a,b) were synthesized in one-pot reaction under phase-transfer catalysis conditions (PTC) starting with cyanoketene S,S-acetals 1 and cyanothioacetamide, cyanoacetamide or cyanoacetohydrazide in different molar ratios. The reaction of 2(a) with halo compounds in equimolar ratio gave thienopyridines 5(a-d). while on using 1:2 molar ratio afforded pyrrolothienopyridines 6(a-d). Also, bis thieno(1,8)naphthyridines 7(a-d) bis-pyrrolo (1,8)naphthyridine 9 and bis(1,6)naphthyridines 10(a-c) were obtained by treating (1,8)naphthyridine 3(a) with the suitable reagents.