A carbohydrate-based synthesis of fused bicyclic ethers by radical cyclization of epoxides using titanocene(III) chloride

摘要

A carbohydrate-based synthesis of both cis- and trans-fused bicylic ethers has been achieved by radical cyclization of epoxides using a transition-metal radical source. Thus, 6-exo radical cyclizations of the carbohydrate derivatives Using [bis(cyclopentadienyl)titanium(III)]chloride (Cp2TiCl) as the radical source has resulted in corresponding cis- and trans-fused bicyclic ethers. While the trans-fused compound has allowed stereoselective radical cyclization, the cis-fused has ended Lip only in a mixture of isomers. The functionalities present in the bicyclic compounds are potential intermediates as multifunctional conformationally rigid scaffolds.