PHOSPHINYLTHIOYLAMINO AND PHOSPHINOTHIOYLAMINO ACIDS AND PEPTIDES .8. NEW PRACTICAL REMOVAL CONDITIONS FOR THE S-MPT GROUP AND THEIR APPLICATION FOR THE SYNTHESIS OF BIS[N,N-DIALLYL-[D-ALA2, L-LEU5]-ENKEPHALYL]CYSTINE

Synthesis of bis left bracket N,N-diallyl- left bracket D-Ala**2, L-Leu**5 right bracket -enkephalyl right bracket cystine, which is expected to be a selective opioid delta -receptor antagonist, was studied. The mercapto group of cysteine was protected by the dimethylphosphinothioyl(Mpt) group. For the removal of this group without damaging the allyl moiety, new mild removal conditions by use of KF/18-crown-6 in a solvent mixture of acetonitrile-methanol are proposed. Bis left bracket D-Ala**2, L-Leu**5 right bracket -enkephalyl right bracket cystine was also prepared in a similar manner.