Synthesis of 3-Substituted Tetrahydrofuran and 4-Substituted Tetrahydropyran Derivatives by Cyclization of Dicarboxylic Acids with InBr3/TMDS

An efficient reduction followed by cyclization of diacid compounds with the InBr3/TMDS system is reported. This system allows the formation of five- and six-membered ring ethers substituted in the 3- or 4-position.