Rhodium‐Catalyzed Annulation of ortho‐Alkenyl Anilides with Alkynes: Formation of Unexpected Naphthalene Adducts

No added oxidant: Two C−H bonds were cleaved in rhodium(III)‐catalyzed reactions of o‐alkenyl N‐triflylanilides with alkynes to produce naphthylamides. Besides the (4C+2C) cycloadducts formally resulting from a dehydrogenative carboannulation process, the reaction also produced variable amounts of isomeric naphthylamides, whose formation requires formal migration of the alkenyl moiety from the ortho to the meta position of the anilide (see scheme).

Abstract

o‐Alkenyl N‐triflylanilides underwent rhodium(III)‐catalyzed oxidative annulations with alkynes to produce different types of naphthylamides in a process which involves the cleavage of two C−H bonds. Remarkably, besides formal dehydrogenative (4C+2C) cycloadducts, the reaction also produces variable amounts of isomeric naphthylamides, whose formation requires a formal migration of the alkenyl moiety from the ortho to the meta position of the anilide. The annulation reaction can be efficiently carried out in the absence of external oxidants, such as Cu(OAc)₂.

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