Medium-ring benzolactams obtained via nickel-catalyzed denitrogenative re-cyclization of benzotriazinones with di(pseudo)haloalkanes

Abstract

A protocol for the denitrogenative re-cyclization of benzotriazinones with di(pseudo)haloalkanes via tandem Ni-catalyzed, Mn-mediated intermolecular cross-electrophile coupling/intramolecular N-alkylation is reported for access to a variety of tetrahydrobenzoazepin-1-ones and tetrahydrobenzoazocin-1(2H)-ones. A unique effectiveness for the medium-ring benzolactams has been observed and explained mechanistically. The substrate scope of the protocol has been demonstrated by more than 30 examples, showing that seven- and eight-membered ring benzolactams with various functional groups could be effectively constructed in yields of up to 98% and 79% using 2 and 5 mol% nickel acetate/2,2′-bipyridine combination as catalysts, respectively.