Cycloadditions of Allylsilanes, Part 12. Regio- and Stereoselective Transformations of Silylbicyclo[n.3.0]alkanes

Abstract

Lewis acid promoted [3 + 2] cycloaddition of 1-acetylcycloalkenes and allylsilanes provides the silylbicyclo[n.3.0]-alkanes 4 and 5. The sequence of regioselective Bayer-Villiger oxidation and elimination of acetic acid affords the 3-silylbicyclo[3.3.0]oct-1(5)-enes 8a and 9a and the 8-(triphenylsilyl)bicyclo[4.3.0]non-1(6)-ene (8b). Epoxidation and catalytic hydrogenation of these olefins proceeds with complete stereoselectivity anti relative to the silyl substituent. Ozonolysis of 8b leads to 3-(triphenylsilyl)cyclononane-1,5-dione (15).