Heterocyclization of 2-thiophenamine: Design of novel thiophene with azole and azine moieties

Abstract

Thiophenamine of type 1 undergo several functionalization and heterocyclization, thus reaction of target 1 with diethyl succinate furnished benzothiophene derivative 4 through condensation followed by intramolecular cyclocondensation and subsequent evolution of 3 H2. Keeping diethyl malonate and amino derivative 1 provide hydroxypyridine derivative 7, may be via 3 °r amine 5 that added the active methylene to the ester group followed by hydrolysis and subsequent decarboxylation. Also, Target 1 undergo cyclocondensation with ethyl acetoacetate to produce acetyl pyridine of type 10. Alkylation of 1 with N-phenyl chloroacetamide provided alkylation derivative 11. Acylation of compound 1 with chloroacetyl chloride followed by cyclization leads to chloropyrrole derivative 14. Compound 14 reacted with NH4SCN to give non isolable pyrrole 15 followed by enolization and subsequent intramolecular cycloaddition providing fused pyrrole 16. Compound 1 reacted with succinic anhydride and ethyl cyanoacetate to provide acylated derivative 17 and aminocyanopyridine 19, respectively. Compound 19 undergo azidolysis and acetylation producing pyridine derivatives 20 and 21, respectively. Compound 19 added its amino group to heteroallene electrophilic carbon of benzoyl isothiocyanate followed by intramolecular heterocyclization producing pyridopyrimidine derivative 23.