Novel C-alkylation Reaction of Condensed Thiophenes with Enaminones, Enaminonitriles, Ethoxymethylene Malononitrile, Aryl Vinyl Ketones and ω-Nitrostyrenes

Abstract

While the thienocoumarin 1 reacts with aryl vinyl ketones, ω-nitrostyrene and ethoxymethylene malononitrile to yield only C-1 alkylation products, it reacts with enaminones (3a–c) to yield either N-alkylated derivatives (4a–c) or a mixture of 4a–c and α,β-unsaturated ketones (9a–c), the former rearranged into the latter on prolonged boiling under reflux in 1,4-dioxane solution in the presence of diethylamine.