Unexpected migration of a benzoyl group in the intramolecular Wittig reaction of o-acyloxybenzylidenephosphoranes with benzoyl chlorides: One-pot synthesis of isomeric 3-benzoyl-2-phenylbenzofurans

Michela Begala

First

;Michele Mancinelli

Second

;Giovanna Lucia Delogu

Last

2020-01-01

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Abstract

The reaction of o-acyloxybenzylidenetriphenylphosphoranes with substituted benzoyl chlorides in an aprotic solvent led, together with the expected 2-phenylbenzofuran, to isomeric 3-benzoyl-2-phenylbenzofuran derivatives. This result formally corresponds to intramolecular migration of the benzoyl group from the ortho oxygen atom to the ylide carbanion via cyclization and ring opening of the starting o-acyloxybenzylidenetriphenylphosphoranes.