Intramolecular Cyclization of Allyl- and Propargylsilanes. The Regio- and Stereochemical Outcome of the Cyclization

Article abstract of DOI:10.1021/jo00251a029

The syntheses of allyl- and propargylsilanes and their additions to enones and dienones are described.Propargylsilanes of type 1 undergo cyclization to spiro<4.5>decanes with EtAlCl2 or TiCl4 as the Lewis acid catalyst.Propargylsilanes of type 2 cyclize upon treatment with EtAlCl2 to fused <4.3.0>nonanes.Allylsilanes of type 15 undergo regioselective 1,6-additions to dienones to form bicyclo<4.5.0>undecenones 21, and propargylsilanes of type 14 cyclize regioselectively in 1,4 fashion (bicyclo<4.3.0>nonanones).Allylsilane 16 forms either a bicyclo<4.6.0>dodecenone (with TiCl4) or a 1:1 mixture of the latter compound and a bicyclo<4.4.0>decanone (with EtAlCl2).