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Versatile Stereoselective Synthesis of Completely Protected Trifunctional α‐Methylated α‐Amino Acids Starting from Alanine
Author(s) -
Altmann Eva,
Nebel Kurt,
Mutter Manfred
Publication year - 1991
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19910740414
Subject(s) - chemistry , alanine , stereoselectivity , enantiomer , amino acid , stereochemistry , catalysis , organic chemistry , biochemistry
A new route to completely protected α‐methylated α‐amino acids starting from alanine is described (see Scheme ). These derivatives, which are obtained via base‐catalyzed opening of the oxazolidinones (2 S ,4 R )‐ and (2 R ,4 S )‐ 2 , can be directly employed in peptide synthesis. The synthesis of both enantiomers of Z‐protected α‐methylaspartic acid β‐( tert ‐butyl)ester ( O 4 ‐( tert ‐butyl) hydrogen 2‐methylaspartates ( R ) or ( S )‐ 4a ), α‐methyl‐glutamic acid γ‐( tert ‐butyl) ester ( O 5 ‐( tert ‐butyl) hydrogen 2‐methylglutamate ( R )‐ or ( S )‐ 4b ), and of N ε ‐bis‐Boc‐protected α‐methyllysine ( N 6 , N 6 ‐bis[( tert ‐butyloxy)carbonyl]‐2‐methyllysine ( R )‐ or ( S )‐ 4c ) is described in full detail.