Heck Reaction on Protected 3-Alkyl-1,2-dien-1-ols: an Approach to Substituted 3-Alkenylindoles, 2-Alkoxy 3-Alkylidene-2,3-Dihydrobenzofuranes and –Indolidines

A phosphine free annulation reaction has been exploited for the preparation of substituted 3-alkenylindoles, 2-alkoxy 3-alkylidene-2,3-dihydrobenzofuranes and -indolidines in good to excellent yields. This has been done by reaction of protected 3-alkyl-1,2-dienols with o-iodophenols or protected o-iodoanilines. Two different heterocyclic skeletons were obtained, this depends on the electrondonating properties of the heteroatom involved in the annulation process.