Longobardo et al. SpringerPlus (2015) 4:553DOI 10.1186/s40064-015-1351-6
RESEARCH
A practical route to β2,3-amino acids with alkyl side chains
Luigi Longobardo1*, Marina DellaGreca1 and Ivan de Paola2
*Correspondence: luilongo@unina.it1 Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Via Cinthia 4, 80126 Naples, Italy
RESEARCH
A practical route to β2,3-amino acids with alkyl side chains
Luigi Longobardo1*, Marina DellaGreca1 and Ivan de Paola2
Full list of author information is available at the end of the articleOp
Abstract
Abstract
en Access
Enantiopure N(Boc)-β3-amino nitriles, valuable synthetic intermediates in the multistep homologation of α-amino
acids, were alkylated using n-BuLi as base.
Alkylations afforded easily separable, almost equimolecular mixtures of diastereomeric N(Boc)-protected syn and anti β2,3-amino nitriles.
Suitable manipulations of both cyano and amino groups eventually led to enantiopure N- and/or C-protected β2,3-amino acids.
For example, methanolysis using conc. HCl gas in MeOH, provides C-protected β2,3 amino acids in excellent yields.
This methodology is applied to the synthesis of a series N(Boc)-β2,3-dialkyl amino nitriles derived from L-phenylalanine, D-phenylalanine, L-valine and one C-protected β2,3 amino acid.
We demonstrate an efficient procedure for the preparation of anti and syn β2,3-amino acids with alkyl side chains, from α-amino acids in reasonable yields.
Alkylations afforded easily separable, almost equimolecular mixtures of diastereomeric N(Boc)-protected syn and anti β2,3-amino nitriles.
Suitable manipulations of both cyano and amino groups eventually led to enantiopure N- and/or C-protected β2,3-amino acids.
For example, methanolysis using conc. HCl gas in MeOH, provides C-protected β2,3 amino acids in excellent yields.
This methodology is applied to the synthesis of a series N(Boc)-β2,3-dialkyl amino nitriles derived from L-phenylalanine, D-phenylalanine, L-valine and one C-protected β2,3 amino acid.
We demonstrate an efficient procedure for the preparation of anti and syn β2,3-amino acids with alkyl side chains, from α-amino acids in reasonable yields.
Keywords: Beta-amino acids, Beta-amino nitriles, Alkylation, Homologation, Carbanions
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