During the elucidation of the structure of the peptide antibiotic Etamycin, NI8-dimethylleucine (I) was disc0vered. l This new amino acid is of biogenetic interest since the corresponding aldehyde, derived from hypochlorite degradation of the amino acid, is structurally and stereochemically identical to the aldehyde obtained from the ozonization of the ergosterol side chain2 In this communication, the synthesis of the, &methylleucines (11), 3 the ...