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

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).