CHEMISTRY OF PHOSPHORYLMETHYL ISOCYANIDES, 6 - 5-DIMETHYL-2-OXO-4-PHENYL-1,3,2-DIOXAPHOSPHORINANE AND 5-DIMETHYL-2-OXO-4-PHENYL-1,3,2-DIOXAPHOSPHORINANE - SYNTHESIS AND STRUCTURE OF THE FIRST CHIRAL ISOCYANOMETHYLPHOSPHONATE SYNTHONS

Both 5-dimethyl-2-oxo-4-phenyl-1,3,2-dioxaphosphorinane (1a) and the t rans epimer 1b have been prepared as potentially useful chiral isocyan omethylphosphonate synthons. 2-Methoxy-1,3,2-dioxaphosphorinanes 5 and the corresponding 2-ethoxy analog 6 were prepared from 2,2-dimethyl-1 -phenyl-1,3-propanediol (2) and were converted in an Arbuzov-type reac tion to 2-(formamidomethyl)oxo-1,3,2-dioxaphosphorinane 7, which upon dehydration gave 1a. Thus, both (+/-)-1a and (2S,4S)-(-)-1a were prepa red, and their molecular structures were determined by single-crystal X-ray analysis. Treatment of (2S,4S)-(-)-1a with KF gave a 1:3 equilib rium mixture of the phosphorus epimers la and Ib, from which the predo minant trans epimer (2S,4R)-(-)-1b was isolated by column chromatograp hy and crystallization.