Chemistry of thienopyridines. XXX. Elaboration of the substituent in 6‐cyanothieno[2,3‐ b ]pyridine

Ten derivatives of thieno[2,3‐ b ]pyridine bearing substituents at the 6‐position are obtained from transformations which start with 6‐cyanothieno[2,3‐ b ]pyridine (2). Treatment of 2 with sodium alkoxide‐alkanol gives imidates (3) in ca. 85% yield. Methyl imidate 3a reacts, in turn, with ammonium chloride to produce a carboxamidine (84%), with 1,ω‐alkyldiamines to form cyclic amidines, and with Meldrum's acid to give an aminoester intermediate (4) (36%). Various reagents then convert 4 into the acetyl derivative (86%) (also obtained directly from 2), an unsaturated aminoester (6) (80%), and a β‐ketoester (7) (39%). Spectral data are reported for these compounds.