Tributyl[2-(trimethylsilyl)-prop-2-enyl]stannane: A Highly Efficient Reagent for the Allylation of Radicals

Abstract

Allylation rates of radicals with tributyl[2-(trimethylsilyl)prop-2-enyl]stannane (2) have been compared with the ones of the (prop-2-enyl)stannane (3) and [2-(methyl)-prop-2-enyl]stannane (4). The Me₃Si substituent showed a rate-accelerating effect (4.2:1 to 6.5:1) relative to the H-atom and the Me group for nucleophilic radicals. With electrophilic radicals, the Me group has a better rate accelerating effect than the Me₃Si group. All these results can be understood by postulating a partially polarized transition state. The 1-substituted vinylsilanes which are produced by radical allylation with 2 have been converted by protiodesilylation and ozonolysis to alkenes and α-hydroxy ketones.