Hydroxy-Directed, SmI(2)-Induced Conversion of Carbohydrates into Carbocycles

Polyoxygenated six-membered carbocycles were derived from carbohydrates with complete stereocontrol through hydroxy-directed coupling cyclization induced by SmI(2). For example, the cis-1,3-cyclohexanediol 3 is obtained from the D-glucopyranoside derivative 1 in excellent yield. The coupling cyclization is initiated by single-electron transfer from SmI(2) to the formyl group of the delta-hydroxy aldehyde 2 generated in an equilibrium process.