Recently the syntheses of several cyclic tripeptides have been claimed. In two instances only amorphous products were~ btained.~.~ In a third case the cyclic peptide product was stated to be crystalline, although it consisted presumably of four stereoisomeric forms (two racemates), since it was obtained by heating glycyl-DL-alanyl-DL-phenylalanine methyl ester under reflux in a methanolic solution containing ammonia.? The cyclic peptide- ...