A. Al-etaibi et al., Novel C-alkylation reaction of condensed thiophenes with enaminones, enaminonitriles, ethoxymethylene malononitrile, aryl vinyl ketones and omega-nitrostyrenes, J CHEM R-S, (1), 1999, pp. 4
While the thienocoumarin 1 reacts with aryl vinyl ketones, omega-nitrostyre
ne 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 alpha,beta-unsaturated ketones (9a-c), the f
ormer rearranged into the latter on prolonged boiling under reflux in 1,4-d
ioxane solution in the presence of diethylamine.