Synthesis of fluorinated 3-pyrrolines and pyrroles via [3+2] annulation of N-aryl fluorinated imines with allenoates catalyzed by phosphine

A phosphine-catalyzed [3 + 2] annulation of N-aryl fluorinated imines with allenoates is reported. A series of fluorinated pyrrolines is obtained in moderate yield, which are further transformed to fluorinated pyrroles via dehydro-aromatization by DDQ in high to excellent yield. The reaction mechanism is also discussed. (C) 2016 Published by Elsevier B.V.