Novel α,α-disubstituted α-aminoacids with axial dissymmetry and their N- or C-protected derivatives

✍ Scribed by Jean-Paul Mazaleyrat; Anne Gaucher; Jaroslav Šavrda; Michel Wakselman

• Book ID: 104361039
• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 934 KB
• Volume: 8
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/s0957-4166(97)00009-8

✦ Synopsis

Racemic as well as enantiomerically pure 1,1'-binaphthyl-substituted 0taminoisobutyric acid (Bin), a new chiral atropoisomeric ~,tx-disubstituted glycine, and its biphenyl analogue (Bip), have been prepared with good yields by bis-alkylation of a glycine tert-butyl ester Schiff base with 2,2'-bis(bromomethyl)-l,l'-binaphthyl and 2,2'bis(bromomethyl)-l,l'-biphenyi, respectively, under phase transfer conditions. The free aminoacids Bin and Bip, as well as their N-protected (Z, Boc, Fmoc) and/or C-protected (ethyl or tert-butyl esters) derivatives, useful for the incorporation of these new aminoacids into peptides, have been obtained. A slow interconversion between the two enantiomers of the Bip derivatives is generally observed in l H NMR at room temperature, with a rotational energy barrier of 59 kJ mol -l. (~) 1997 Elsevier Science Ltd. All rights reserved.