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Synlett 2002(10): 1688-1690
DOI: 10.1055/s-2002-34221
LETTER
© Georg Thieme Verlag Stuttgart · New York

Palladium-based Kinetic Resolution of Racemic Tosylaziridines

Wa-Hung Leung*a, Wing-Leung Maka, Eddie Y. Y. Chana, Tony C. H. Lama, Wing-Sze Leeb, Hoi-Lun Kwongb, Lam-Lung Yeung*a
a Department of Chemistry and Open Laboratory of Chirotechnology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
e-Mail: chleung@ust.hk; e-Mail: chyeungl@ust.hk;
b Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
Fax: +852(2358)1594;
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Publication History

Received 23 August 2002
Publication Date:
23 September 2002 (online)

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Abstract

Dicationic Pd(II) complexes with chiral pyridine bis(oxazoline) ligands are catalysts for kinetic resolution of racemic styrene tosylazirdines. Treatment of styrene tosylaziridine with 0.5 equivalents of alcohol in the presence of the chiral Pd catalyst affords β-alkoxy tosylamide with ee up to 71%.

Key words

palladium - kinetic resolution - aziridine - asymmetric - alcoholysis

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Typical procedure for Pd-catalyzed alcoholysis of styrene tosylaziridine: To a mixture of aziridine (50 mg, 0.18 mmol) and S-1 (12 mg, 0.018 mmol) in CH2Cl2 (1 mL) was added dried MeOH (4 µL, 0.09 mmol) under nitrogen at 0 °C. The mixture was stirred at that temperature for 1-5 h and purified by flash chromatography (silica gel, 50% ether-hexane). Spectroscopic data for PhCH(OMe)CH2NHTs: 1H NMR (400 MHz, acetone-d 6): δ 7.90 (d, J = 8.0 Hz, 2 H), 7.53 (d, J = 8.0 Hz, 2 H), 7.45 (m, 5 H), 6.65 (s, br, 1 H), 4.35 (dd,
J = 8.8, 4.4 Hz, 1 H), 3.20 (m, 2 H), 3.25 (s, 3 H), 2.56 (s,
3 H); 13C NMR (100 MHz, acetone-d 6): δ 143.5, 140.0, 139.0, 130.1, 129.1, 128.7, 127.6, 127.3, 83.0, 56.8, 50.2, 21.3; MS (+CI) m/z (relative intensity): 306 (M + H+, 18), 274 (M - OMe+, 100). Anal. Calc. for C16H19NOS3 (305.39): C, 62.93; H, 6.27; N, 4.59. Found: C, 62.91; H, 6.35; N, 4.54.

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Leung, W.-H.; Chan, E. Y. Y.; Wong, W.-T., unpublished results.

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Initial rates of reactions were estimated by monitoring the concentration of aziridine using GLC.