Synthesis and characterization of some new pyridines, thieno[2,3‐ b ] pyridines and pyrido[3′,2′:4,5]thieno[3,2‐ d ]pyrimidine‐4(3 H )‐ones bearing styryl moiety

Abstract 3‐Cyano‐5‐ethoxycarbonyl‐6‐methyl‐4‐styrylpyridine‐2(1 H )‐thione ( 3 ) was prepared by reaction of 2‐cyano‐5‐phenylpenta‐2,4‐dienethioamide ( 2 ) with ethyl acetoacetate or by multicomponent reaction of cinnamaldehyde ( 1 ), cyanothioacetamide and ethyl acetoacetate in a moderate yield. Reaction of compound 3 with some N ‐aryl‐2‐chloroacetamides, in the presence of sodium acetate, gave the corresponding 2‐( N ‐arylcarbamoylmethylsulfanyl)‐3‐cyano‐5‐ethoxycarbonyl‐6‐methyl‐4‐styrylpyridines 4a‐f . When compounds 4a‐f were subjected to Thorpe‐Ziegler reaction conditions, they converted into the corresponding 3‐amino‐5‐ethoxycarbonyl‐2‐( N ‐arylcarbamoyl)‐6‐methyl‐4‐styrylthieno[2,3‐ b ]pyridines 5a‐f . Compounds 5a,e,f were reacted, in turn, with 2,5‐dimethoxytetrahydrofuran to furnish the corresponding 3‐(pyrrol‐1‐yl)thieno‐pyridines 6a,e,f . Reactions of 5a‐f with triethyl orthoformate or nitrous acid were also carried out and their products were identified. Structural formulas of all synthesized compounds was characterized and confirmed on the basis of their elemental and spectral analyses.