Highly Regio- and Diastereoselective One-Pot Synthesis of Silyl Epoxy Alcohols and Vinylsilanes by Direct Hydroxy-Epoxidation

Article abstract of DOI:10.1021/jo00091a021

A direct synthesis of silyl epoxy alcohols from vinylsilanes is described.It consists of the regioselective ene reaction of the vinylsilanes with singlet oxygen, which proceeds with predominant hydrogen abstraction at the position geminal to the silyl group.The resulting silyl allylic hydroperoxides were treated, without isolation, subsequently with Ti(O-i-Pr)4 to afford the silyl epoxy alcohols in good yields and very high diastereomeric ratios, which ranged from 93:7 to greater than 97:3.Alternatively, the vinylsilanes were photooxygenated directly in the presence of the titanium catalyst and the silyl epoxy alcohols obtained in good yields.The method was applied to di- and trisubstituted acyclic vinylsilanes with a methyl group geminal to silicon and cyclic derivatives all give consistently good results.In this novel hydroxy-epoxidation, the regioselectivity of the singlet oxygen ene reaction as well as the diastereoselectivity of the oxygen transfer can be controlled by the steering effects of the silyl group.