NUCLEOPHILIC-SUBSTITUTION REACTION OF OPTICALLY PURE CHLOROSELENURANEWITH ACTIVE METHYLENE-COMPOUNDS - FORMATION OF OPTICALLY PURE SELENONIUM YLIDES

Nucleophilic substitution reaction of (R(Se))-chloroselenurane 1 with active methylene compounds proceeded in highly stereoselective manner with retention of configuration to give (S-Se)-selenonium ylides 2. (S -Se)- and (R(Se))-Ylides, 2 and 3, were stereospecifically formed from the reaction of (R(Se))- and (S-Se)-selenoxides, 4 and 5, with active methylene compounds.