Catalytic cyclization of o-alkynyl phenethylamines via osmacyclopropene intermediates: direct access to dopaminergic 3-benzazepines

Abstract

A novel osmium-catalyzed cyclization of o-alkynyl phenethylamines to give 3-benzazepines is reported. The procedure allows the straightforward preparation of a broad range of dopaminergic 3-benzazepine derivatives. Mechanistic investigations revealed that the process takes place via osmacyclopropene intermediates, which were isolated and characterized by X-ray crystallography.This research was supported by the MICINN (projects CTQ2011-28258, CTQ2014-52799-P, and CTQ2014-51912REDC), Xunta de Galicia and the European Regional Development Fund (projects GRC2014/032 and EM 2012/051), the DGA (E-35), and the European Social Fund (SFE). A.A.-P.and C.G.-R. thank the Spanish MICINN for a pre-doctoral FPI fellowship and Juan de la Cierva Contract (JCI-2011-09946), respectively.Peer Reviewe