OPTICALLY-ACTIVE TRIVALENT PHOSPHORUS-COMPOUNDS .2. REACTIVITY OF ALKYLTHIO-PHOSPHONIUM AND ALKYLSELENO-PHOSPHONIUM SALTS - 1ST STEREOSPECIFIC SYNTHESIS OF A CHIRAL PHOSPHINITE

It was shown that alkylthio-and alkylselenophosphonium salts react with alkylmercaptide anions to give trivalent phosphorus compounds and disulfides. Reaction of (—)-(5)-methylthiomethyl-n-propylphenylphosphonium triflate (6) with ethylmercaptide anion gave completely racemic methyl-n-propylphenylphosphine (7). However, when tert-butylmercaptide anion was used, optically active phosphine 7 was formed with 59% of initial optical activity and with retention of configuration. Reaction between (—)-(5)-methylthioethyl-tert-butylphenylphosphonium triflate (8) and sodium ethylmercaptide was found to occur with full stereospecificity to give (+)-(R)-ethyl-tert-butylphenylphosphine (10). (—)-(S)-0-Methyl-Se-methyl-tert-butylphenylphosphonium triflate (II) obtained from (—)-(5)-tert-butylphenylphosphinoselenoic acid (12) was converted stereospecifically to (+)-(R)-O-methyl Jerr-butylphenylphosphinite (2). The latter reaction represents the first stereospecific synthesis of a chiral trivalent phosphorus acid ester. © 1979, American Chemical Society. All rights reserved.