Tin-free radical cyanation and allylation reactions

Abstract

The radical reaction of tin-based reagents has a difficulty in industrial and biological applications because of inherent toxicity of organotin derivatives. We investigated tin-free radical cyanation and allylation reactions based on thermal decomposition of sulfonyl radical and iodine and xantate transfer. Using methanesulfonyl cyanide, tin free cyanation worked well with benzylic and tertiary iodides and less efficiently with secondary alkyl iodides. However, the reaction with primary alkyl iodides gave the direct addition product due to inefficient iodine transfer. Tin-free radical allylation reaction were examined with primary and secondary alkyl iodides. Our approach is based on the iodine atom transfer from alkyl iodide to vinyl radical by radical cyclization of alkyl radical to an alkyne group. We designed various allyl sulfone derivatives bearing alkyne, activated alkyne and gem-malonate moiety. However, due to slow rate in radical cyclization and iodine atom transfer, the satisfactory yields were not obtained.