Use of carbohydrate derivatives for studies of phosphorus stereochemistry. Part 8. Preparation and some reactions of 1,3,2-oxazaphospholidine-2-ones and -2-thiones derived from 2-deoxy-3,4,6-tri-O-methyl-2-methylamino-D-glucopyranose

Abstract

The four cyclic phosphorus esters from the reaction of MePSCl2 with 2-deoxy-3,4,6-tri-O-methyl-2-methylamino-D-glucopyranose (1) have been separated with difficulty, and structures assigned. Ring-opening of the isomers and subsequent detachment of the chiral phosphorus group from the carbohydrate moiety occurs in both acid and base, the nature of the products varying with reaction conditions and initial stereochemistry. In acid the P–N bond is broken first and then the C–O bond. In base P–N and P–O bonds are cleaved competitively; when the P–N bond is cleaved first subsequent detachment of the phosphorus group from the carbohydrate occurs by C–O and P–O bond cleavage depending on the anomeric configuration and on the concentration of the base. The P–N and P–O bond breaking reactions are highly stereoselective occurring with inversion of configuration. Reactions of (1) with PhPSCl2, MePOCl2, and PhPOCl2 and ring-opening of the resultant esters are also described.