Microwave accelerated Castagnoli-Cushman reaction: Synthesis of novel 6,7,8,9-tetrahydropyrido[3′,2′:4,5]pyrrolo[1,2-a]pyrazines.

[Display omitted] • 6,7,8,9-Tetrahydropyrido[3′,2′:4,5]pyrrolo[1,2- a ]pyrazines cores are featured in many bioactive compounds. • A novel approach to these privileged cores is described. • Microwave irradiation enriched Castagnoli-Cushman Reaction effectiveness and faster reaction times. • It involves the use of azaindole dicarboxylic acid and acetic anyhydride. • It dehydrates the diacid into its cyclic anyhdride which enters the Castagnoli-Cushman Reaction. The Castagnoli-Cushman reaction of various azaindole dicarboxylic acids with imines using acetic anhydride as a dehydrating agent was significantly accelerated by microwave irradiation. The reaction conditions offer a convenient preparation of novel 6,7,8,9-tetrahydropyrido[3′,2′:4,5]pyrrolo[1,2- a ]pyrazines in moderate to good yields with good trans stereoselectivity. [ABSTRACT FROM AUTHOR]