A three-component condensation of cyclic enamino ketones, phenylglyoxal hydrate, and ethyl cyanoacetate

A three-component condensation of cyclic enaminones, phenylglyoxal hydrate, and ethyl cyanoacetate in EtOH gave a number of 4,5,6,7-tetrahydroindole functional derivatives. The corresponding intermediates, 2,3,4,5,6,7-hexahydroindoles, are formed under mild conditions. Under more severe conditions (heating under reflux in DMF), cleavage of the ethoxycarbonyl group takes place.