Practical Stereoselective Synthesis of β-Branched α-Amino Acids through Efficient Kinetic Resolution in the Phase-Transfer-Catalyzed Asymmetric Alkylations

Takashi Ooi, Daisuke Kato, Koji Inamura, Kohsuke Ohmatsu and Keiji Maruoka*

*Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan, Email: maruokakuchem.kyoto-u.ac.jp

T. Ooi, D. Kato, K. Inamura, K. Ohmatsu, K. Maruoka, Org. Lett., 2007, 9, 3945-3948.

DOI: 10.1021/ol701558e

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Abstract

Phase-transfer-catalyzed alkylation of glycinate Schiff base with racemic secondary alkyl halides proceeded with excellent levels of syn- and enantioselectivities under the influence of a chiral quaternary ammonium bromide and 18-crown-6. The alkylation product can be selectively converted to the corresponding anti isomer, allowing the preparation of all the stereoisomers of β-alkyl-α-amino acid derivatives.

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N-Spiro Chiral Quaternary Ammonium Bromide Catalyzed Diastereo- and Enantioselective Conjugate Addition of Nitroalkanes to Cyclic α,β-Unsaturated Ketones under Phase-Transfer Conditions

T. Ooi, S. Takada, S. Fujioka, K. Maruoka, Org. Lett., 2005, 7, 5143-5146.

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Key Words

O'Donnell Amino Acid Synthesis, Organocatalysis

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ID: J54-Y2007-3060