Synlett 2003(12): 1931-1933  
DOI: 10.1055/s-2003-41478
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© Georg Thieme Verlag Stuttgart · New York

A New N-Spiro C2-Symmetric Chiral Quaternary Ammonium Bromide Consisting of 4,6-Disubstituted Biphenyl Subunit as an Efficient Chiral Phase-Transfer Catalyst

Takashi Ooi, Yasushi Kubota, Keiji Maruoka*
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
Fax: +81(75)7534041; e-Mail: maruoka@kuchem.kyoto-u.ac.jp;
Further Information

Publication History

Received 4 June 2003
Publication Date:
19 September 2003 (online)

Abstract

A new N-spiro chiral quaternary ammonium bromide has been designed and assembled from optically active 4,6-disubstitute­d biphenyl subunits. Its utility as an efficient chiral phase-transfer catalyst has been clearly demonstrated by application to the highly enantioselective alkylation of tert-butyl glycinate benzophenon­e Schiff base.

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Spectroscopic Characterization of 1b: [α]D 22 +156.2 (c 0.31, CHCl3). 1H NMR (400 MHz, CDCl3): δ = 7.37 (4 H, m, Ar-H), 7.21-7.32 (16 H, m, Ar-H), 7.14-7.19 (4 H, m, Ar-H), 7.04 (4 H, br d, J = 1.6 Hz, Ar-H), 3.87 (4 H, d, J = 13.2 Hz, ArCH2), 3.64 (4 H, d, J = 13.2 Hz, ArCH2), 2.18 (12 H, s, ArCH3), 1.68 (24 H, s, ArCCH3). 13C NMR (100 MHz, CDCl3): δ = 150.8, 149.7, 137.5, 135.5, 131.2, 128.2, 127.5, 126.7, 126.5, 125.8, 60.3, 42.9, 31.0, 30.5, 20.2. IR (KBr): 2963, 2928, 2870, 1740, 1680, 1601, 1495, 1445, 1383, 1364, 1232, 1202, 1097, 1076, 1030, 845, 768, 702 cm-1. HRMS (ESI-TOF): Calcd for C68H72N: 902.5659 (M+). Found: 902.5673 (M+).