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Synthesis 2010(10): 1673-1677
DOI: 10.1055/s-0029-1218707
DOI: 10.1055/s-0029-1218707
PAPER
© Georg Thieme Verlag
Stuttgart ˙ New York
N-Benzyl-Protection of Amino Acid Derivatives by Reductive Alkylation with α-Picoline-Borane
Further Information
Received
19 January 2010
Publication Date:
24 March 2010 (online)
Publication History
Publication Date:
24 March 2010 (online)
Abstract
A convenient method for N-protection of amino acid derivatives with a benzyl group by reductive alkylation of amino acid derivatives with α-picoline-borane is described. Amino acid esters or amino alcohols were treated with aryl aldehydes in methanol/acetic acid in the presence of α-picoline-borane to give N-benzyl-protected amino acid derivatives in good yields.
Key words
amino acid esters - amino alcohols - benzylation - protecting groups - reductions
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Thermal stabilities of α- and γ-picoline-borane were examined. They were non-explosive at 100 ˚C and did not decompose under ambient conditions over two years judging from the HPLC analysis of the products.