DBU mediated coupling of isatin with phenacyl azides: synthesis of 2-oxoindolin-3-ylbenzoates

Abstract

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) catalyzed redox neutral coupling of isatin with phenacyl azides in acetonitrile to yield 2-oxoindolin-3-yl benzoates under mild reaction conditions was developed. The scope of the reaction that leads to the formation of a new C–O and C–H bond in the overall transformation was explored by synthesizing more than 35 examples in high yields (70–85%). Un-substituted phenacyl azides as well as those bearing electron donating groups (Me, OMe, OH, OCH₂O), halogen atoms (Cl, Br) or electron withdrawing group (CN, NO₂) led to the reductive aroylation of isatin in high yields in a short reaction time (6 h).