Nucleophilic acylation of o-quinone methides: An umpolung strategy for the synthesis of α-aryl ketones and benzofurans

The synthesis of α-aryl ketones is accomplished by the direct nucleophilic acylation of o-quinone methide electrophiles. In this process, two reactive intermediates, carbonyl anions and o-quinone methides, are generated in one flask upon treatment of the corresponding thiazolium carbinols and silyl protected phenols with a soluble fluoride source. These intermediates then undergo productive addition reactions to afford the desired α-aryl ketone adducts. This new strategy has been applied to a short synthesis of the natural product demethylmoracin I.