Herstellung enantiomerenreiner, α‐alkylierter Lysin‐, Ornithin‐ und Tryptophan‐Derivate

Synthesis of Enantiomerically Pure, α‐Alkylated Lysine, Ornithine, and Tryptophan Derivatives The imidazolidinones 9 and 10 as well as the oxazolidinone 18a were prepared in several steps by known methods from lysine and ornithine with an overall yield of ca. 20%. After double deprotonation with LDA, the corresponding dianionic derivatives could be diastereoselectively alkylated with electrophiles (MeI, C 6 H 5 CH 2 Br, C 6 H 5 CHO, CH 3 CHO). Acid hydrolysis led to the two enantiomeric 2‐methyl‐ and 2‐benzyllysines and to the enzyme inhibitor ( S )‐2‐methylornithine. Several α‐alkylated tryptophan derivatives were obtained through alkylation of the heterocycles derived from various amino acids with 1‐( tert ‐butyloxycarbonyl)‐3‐(bromomethyl)indole ( 26 ). Alkaline hydrolysis of the five‐membered auxiliary ring of 30b followed by treatment with HCl afforded ( S )‐2‐methyltryptophan ( 31 ).