Stereoselective synthesis of dipeptides - I

Article abstract of DOI:10.1016/S0957-4166(97)00013-X

The alkylation of 7 occurs in moderate to good trans stereoselection (d.e.40-98%), while a poorer d.e. (40-98%) is observed for 8. On the contrary, in both substrates the alkylation with CH₃I produces a greater amount of the cis isomer (d.e.48%).). Cleavage of the lactims 9(a,e) gives enantiomerically pure dipeptides 14(a,e). The absolute configuration of the introduced stereogenic centres has been assigned on the basis of the ¹H-NMR data in connection with the conformational analysis.