Asymmetric PTC for Preparation of a-Amino Acids

H.-g Park; M.-J. Kim; M.-K. Park; H.-J. Jung; J. Lee; S.-h Choi; Y.-J. Lee; B.-S. Jeong; J.-H. Lee; M.-S. Yoo; J.-M. Ku; S.-s Jew

doi:10.1055/s-2005-869889

Synfacts, Table of Contents

Synfacts 2005(0): 0085-0085
DOI: 10.1055/s-2005-869889

Polymer-Supported Synthesis

Asymmetric PTC for Preparation of a-Amino Acids

Contributor(s): Yasuhiro Uozumi, Yoichi M. A. Yamada, Naoshi Fukuyama

H-g. Park*, M.-J. Kim, M.-K. Park, H.-J. Jung, J. Lee, S-h. Choi, Y.-J. Lee, B.-S. Jeong, J.-H. Lee, M.-S. Yoo, J.-M. Ku, S-s. Jew*
Seoul National University, Korea
Highly Enantioselective Phase-Transfer Catalytic Alkylation in the Preparation of Non-Natural α-Amino Acids via Solid Phase Synthesis Using Aldimine Linker
J. Org. Chem. 2005, 70: 1904-1906

Abstract

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Key words

aldimine linker - phase-transfer catalysts - alkylation

Significance

A polystyrene resin-bound phenylmethyleneglycinimine tert-butyl ester was prepared from a Merrifield resin in two steps. The polymer-bound glycinimine was alkylated with alkyl halides (e.g., hexyl bromide, allyl bromide, propargyl bromide, benzyl bromide, etc.) in the presence of 10 mol% of a cinchona-derived phase transfer catalyst and 50% aqueous CsOH in toluene/chloroform at 0 °C, for four days to give the corresponding non-natural α-amino acids in 50-82% yields with up to 99% ee. Eleven examples of the alkylation are shown.

Comment

This method is very useful to construct the chiral non-natural α-amino acids library for combinatorial synthesis.

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