Aryl annulation of cyclic ketones via a magnesium carbometalation-6-pi- electrocyclization protocol

Org Lett. 2005 Mar 3;7(5):767-70. doi: 10.1021/ol047602y.

Abstract

A new strategy for the aryl annulation of cyclic ketones is described. Palladium(0) coupling of a propargyl alcohol with the enol triflate of a ketone and addition of vinylmagnesium chloride generates a triene as a magnesium chelate that may be quenched with an electrophile. In some cases, the triene cyclizes under the reaction conditions. Aromatization is accomplished by exposure to manganese dioxide or dichlorodicyanoquinone (DDQ). [reaction: see text]