Document Detail

Stereoselective Synthesis of Unsaturated and Functionalized L-NHBoc aminoacids, using Wittig Reaction under Mild Phase-Transfer Conditions.
MedLine Citation:
PMID:  22870957     Owner:  NLM     Status:  Publisher    
The stereoselective synthesis of a new amino acid phosphonium salt was described by quaternization of melting triphenylphosphine with the γ-iodo NHBoc-amino ester, derived from L-aspartic acid. The deprotection of the carboxylic acid function to afford the phosphonium salt with a free carboxylic acid group, was achieved by a palladium catalyzed desallylation reaction. This phosphonium salt was used in the Wittig reaction with aromatic or aliphatic aldehydes and trifluoroacetophenone, under solid-liquid phase-transfer conditions in chlorobenzene and in presence of K3PO4 as weak base, to afford the corresponding unsaturated amino acids without racemization. Thus, the reaction with substituted aldehydes allows to graft various functionalized groups on the lateral chain of the amino acid, such as trifluoromethyl, cyano, nitro, ferrocenyl, boronato or azido. In addition, the reaction of the amino acid Wittig reagent with α,β-unsaturated aldehydes, leads to amino acids bearing a diene on the lateral chain. Finally, this amino acid phosphonium salt appears to be a new powerful tool for the preparation of unsaturated and non-proteinogenic α-amino acids, directly usable for the synthesis of customized peptides.
Emmanuelle Rémond; Jérôme Bayardon; Marie-Joêlle Ondel-Eymin; Sylvain Jugé
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-7
Journal Detail:
Title:  The Journal of organic chemistry     Volume:  -     ISSN:  1520-6904     ISO Abbreviation:  J. Org. Chem.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985193R     Medline TA:  J Org Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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