Access to Indole- And Pyrrole-Fused Diketopiperazines via Tandem Ugi-4CR/Intramolecular Cyclization and Its Regioselective Ring- Opening by Intermolecular Transamidation

摘要

An efficient approach for the synthesis of indole- and pyrrole-fused diketopiperazines has been developed. Thisnprotocol involves the Ugi four-component reaction (U-4CR) followed by an intramolecular cyclization of the Ugi products atnroom temperature to afford the desired products in good to excellent yields. In addition, it is interesting to report the subsequentnregioselective ring-opening of diketopiperazine unit occurring via an intermolecular transamidation reaction under mildncondition, resulting in the formation of highly functionalized indole-2-carboxamides and pyrrole-2-carboxamides.