α-vinylation of β-aminothiophene derivatives. Synthesis of 6- functionalized thieno[3,2-b]pyridines

Article abstract of DOI:10.1016/S0040-4020(98)00565-1

The acid-catalyzed reductive α-alkylation of β-aminothiophenes was applied to the N-(thien-3-yl)acetamide and alkyl N-(thien-3-yl)carbamates. Without reduction, β-amino α-vinylthiophenes were obtained when α-branched aldehydes were used. β-(3-Aminothien-2-yl)α,β-unsaturated ketones, esters and nitriles were also prepared from the corresponding α-functionalized acetals. These amines are intermediates in the formation of thieno[3,2- b]pyridines bearing a functional group at the β-position of the pyridine ring.