Synthesis and conformations of 2,3:4,5- and 2,4:3,5-di- O-isopropylidene- d-mannitol

Abstract

The 2,3:4,5- ( 8) and 2,4:3,5-di- O-isopropylidene ( 10) derivatives of d-mannitol have been prepared from 1,6-di- O-benzoyl- d-mannitol and their structures established by 13C-n.m.r. spectroscopy. The 1,3-dioxane rings in 10 adopt a skew conformation and the sugar carbon chain in 8 is bent around the C-3-C-4 bond, as found by i.r. data and molecular mechanics calculations. Oxidation of 8 with pyridinium dichromate gave 2,3:4,5-di- O-isopropylidene- d-mannono-1,6-lactone ( 12).