New P-Chiral Phosphates, Phosphorothioates and Phosphoroselenothioates

Abstract

Easily available pure diastereoisomers of (Rp,Rc)-and (Sp,Sc)-O,Se-dimethyl N-α-methylbenzyl phosphoramidosele-noate (12) and S-methyl-N-phenyl-N'-α-methylbenzyl phosphordi-amidothioate (9) are converted into enantiomers of O,S,Se-trimethyl phosphoroselenothioate (16) and S-methyl-S-ethyl-S-n-propyl phosphorotrithioate (two-step procedure)(15), respectively. Partial P-epimerizations observed during these conversions are discussed in terms of stereomutation of pentacoordinated phosphorus intermediates, while metaphosphoramidates are responsible for the formation of side-products.