IMPROVED SYNTHESIS OF 3-SPIRO INDOLINES IN DRY MEDIA UNDER MICROWAVE IRRADIATION

Abstract

An efficient, one-pot synthesis of novel spiro [indole-dipyrrolopyridines] (8) was achieved under microwave irradiation by the interaction of spiro [indole-dipyrrolopyrans] (3) with ammonium acetate (7) in the presence of acetic acid. Spiro [indole-dipyrrolopyrans] (3) were synthesized “in situ” by the reaction of indole-2,3-diones (1) and 2-pyrrolidone (2) in 1:2 molar ratio by microwave induced techniques for the first time. Comparative studies have been made between (a) microwave irradiation of (i) neat reaction of reactants in the absence of any solvent or catalyst (ii) reaction in presence of o-dichlorobenzene and (b) classical heating.