1. The stereoselectivity of thiol addition to dehydrodipeptides was examined under various conditions, Thiolate-catalyzed addition of thiols to dehydroalanyl-prolineamides (7-10) results in formation of D-cysteinyl-peptides with high optical yields. Almost no stereoselectivity is found during addition to the analogous dehydroalanyl-peptides, containing L-proline ester (1 1) or L-prolinol (12), to the prolyl-dehydroalanine peptide 14, ...
