Intramolecular cyclizations of allyl- and prop-2-ynyl-silanes with the terminal group governing the regiochemical outcome of the cyclization

Abstract

The intramolecular additions of allyl- and prop-2-ynyl-silanes to enones and dienones are described; cyclizations carried out using 1.1 equiv. of either EtAlCl₂ in toluene or TiCl₄ in methylene chloride at low temperature have shown that the terminal group governs the regiochemical outcome of the cyclization, with allylsilane leading to 1,6 addition and prop-2-ynylsilane to 1,4 addition.