Synthesis and Conformational Analysis of (6R)--1,2:3,4-Di-O-isopropylidene-α-D-galactopyranose. NMR and Molecular Modeling Studies

Article abstract of DOI:10.1021/jo00095a019

The conformation preferences of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose have been determined using NMR and molecular modeling (conformational searching) techniques.The pyranose ring assumes a skew-boat conformation.Coupling constants for the C6 side chain and hydroxyl proton indicate that the predominant conformation places the oxygen anti to C4 (gt conformation) with the hydroxyl hydrogen aligned toward the pyranose oxygen in deuteriochloroform.A similar orientation of the C5-C6 bond was observed in water and toluene.In DMSO the C6 oxygen is anti to the pyranose oxygen (tg conformation) with the hydroxyl hydrogen anti to C5.A similar orientation of the C5-C6 bond was observed in methanol.