Synthesis of 3-pyrrolines, annulated 3-pyrrolines, and pyrroles from alpha-amino allenes.

Abstract

Alpha-amino allenes, readily prepared from reaction of alpha-(N-carbamoyl)alkylcuprates with propargyl substrates followed by N-Boc deprotection, are converted in high yields to pyrrolines with AgNO(3). Palladium-catalyzed cyclization of amino allenes affords either the pyrroline or the pyrrole depending on reaction conditions and provides for introduction of an aryl substituent at the C-3 position of the pyrroline or pyrrole. Enantioenriched pyrrolines are readily prepared from scalemic propargyl alcohols. [reaction: see text]