Regio- and Enantioselective Catalytic Cyclization of Pyrroles onto <i>N</i>-Acyliminium Ions

Abstract

The regio- and enantioselective cyclization of pyrroles onto N-acyliminium ions generated in situ from hydroxylactams is reported. Modest to excellent ee's and yields are obtained in these novel Pictet-Spengler-type reactions with a chiral thiourea-pyrrole catalyst. Useful synthetic transformations of the versatile pyrroloindolizidinone and pyrroloquinolizidinone products are presented.