Synthesis of 9<i>H</i>-Pyrrolo[1,2-<i>a</i>]indole and 3<i>H</i>-Pyrrolizine Derivatives via a Phosphine-Catalyzed Umpolung Addition/Intramolecular Wittig Reaction

Abstract

The first umpolung addition/intramolecular Wittig reaction, catalytic in phosphine, is described. The in situ phosphine oxide reduction was accomplished by the use of silane and a catalytic amount of bis(4-nitrophenyl)phosphate. This catalytic protocol is applicable to the synthesis of a wide range of functionalized 9H-pyrrolo[1,2-a]indoles and pyrrolizines (18 examples, 70-98% yields).