METHANOLYSIS AND RING-OPENING ISOMERIZATION REACTION OF ORO-4-PHENYL-5,5-DIMETHYL-1,3,2-DIOXAPHOSPHORINANE 2-OXIDE(2-SULFIDE)

The stereochemistry of methanolysis reaction of trans - 2 - chloro - 4 - phenyl - 5,5 - dimethyl - 1,3,2 - dioxaphosphorinane 2 - oxide (tra ns - 1) and cis - 2 - chloro - 4 - phenyl -5,5 - dimethyl - 1,3,2 - di oxaphosphorinane 2 - sulfide (cis - 2) were described. Trans - 1 was t reated with methanol to give inversion product at phosphorus. In contr ast, retention is favored while the reaction employs methoxide ion as the nucleophile. Reaction of cis - 2 with sodium methoxide in methanol under reflux led to a ring opening followed by ring closure to give a thermodynamically controlled mixture of diastereomeric isomers in whi ch trans isomer was the major component. An acyclic intermediate is fo und to be involved in this process.