Silyl Phosphites. 21. A New Method for the Synthesis of L-Ascorbic Acid 2-O-Phosphate by Utilizing Phosphoryl Rearrangement

Article abstract of DOI:10.1021/jo00139a014

A stabilized form of vitamin C, L-ascorbic acid 2-O-phosphate (1), was successfully synthesized by a new method via a fully trimethylsilylated L-ascorbic acid (4) that was prepared in high yield by silylation of L-ascorbic acid with hexamethyldisilazane.Bromination of 4 gave an adduct (6) that was isomerized during distillation to a trimethylsilylated bicyclic half acetal (8) of dehydroascorbic acid.Addition of tris(trimethylsilyl) phosphite (TMSP) to 8 gave carbonyl addition compounds 9a and 9b, which underwent thermal rearrangement to give a mixture of bis(trimethylsilyl)-3,5,6-tris-O-(trimethylsilyl)-L-ascorbic acid 2-O-phosphate (10) and its 3-O-isomer 13 in the ratio of 88:12.Treatment of the mixture with cyclohexylamine in methanol gave selectively tricyclohexylammonium salt of L-ascorbic acid 2-O-phosphate in 53percent yield.