Reactions of Alkyl Diphenylphosphinates and Related Thio Esters with Some Nucleophiles. SN2 (S) Reaction and Wittig Type Rearrangement

Reactions of alkyl diphenylphosphinates Ph2P(=X)YCHR1R2 (X, Y=O,S) with organolithiums and Grignard reagents afforded different types of products depending on the combination of X and Y. When Y=O, the reagents (R3M) mainly attacked the phosphorus atom to give Ph2P(=X)R3 and R1R2XCHO− irrespective of X, while, when X=Y=S, the reaction occurred exclusively at the ester sulfur atom, SN2(S), to give R3SCHR1R2 and [Ph2PS]−. When the X=O and Y=S, a Wittig type rearrangement of a carbanion [Ph2P(=O)SCR1R2]− was observed along with attacks on the phosphorus (major) and the sulfur (minor) atoms. Reactions with some other nucleophiles (hydride, amide and alkoxide ions) are also described.