Adduct formation between pyridine-2-thiones and acetylenic carbonyl derivatives

Abstract

1 : 1 Adducts are formed between pyridine-2-thiones and acetylenic amides, esters, and ketones. The reaction rate increases with increase in activation of the triple bond by the carbonyl group and is affected by the pyridine 6-substituent, which also may influence the stereochemical course. The product isomer ratios corresponding to kinetic control were obtained in chloroform; the amides yielded mainly the cis-isomers, the ketones the trans-isomers, and the esters a slight preponderance of the cis-isomers.