Aryl Annulation of Cyclic Ketones via a Magnesium Carbometalation−6-π- Electrocyclization Protocol

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]