SYNTHESIS AND CONFORMATION OF cyclo(- d - OR l -TYR(ME)- l -ILE- l -PRO- l -LEU-), DIASTEREOMERIC AND SIMPLIFIED ANALOGS OF CYL-2

Diastereomeric cyclotetrapeptides, cylol (-d- or l-Tyr(Me)-l-Ile-l-Pro-l-Leu-) (1d or 1l) which are simplified analogs of a phytotoxin Cyl-2, have been synthesized. A conformation with trans-trans-cis-trans peptide bonds,l-Ile-l-Pro bond being cis, is proposed for 1d on the basis of 1H-and 13C-NMR data.