Synlett 2008(3): 367-370  
DOI: 10.1055/s-2008-1032047
LETTER
© Georg Thieme Verlag Stuttgart · New York

Preparation of Optically Active 1,2-Diol Monotosylates by Enzymatic Hydrolysis

Yasutaka Shimada, Hiroshi Sato, Shinji Minowa, Kazutsugu Matsumoto*
Department of Chemistry, Meisei University, Hodokubo 2-1-1, Hino, Tokyo 191-8506, Japan
Fax: +81(42)5917360; e-Mail: mkazu@chem.meisei-u.ac.jp;
Further Information

Publication History

Received 14 November 2007
Publication Date:
16 January 2008 (online)

Abstract

An easy preparation of optically active 1,2-diol monotosylate derivatives by enzymatic hydrolysis is disclosed. Lipase PS (Burkholderia cepacia) catalyzes the hydrolysis of racemic 2-acetoxyhexyl tosylate with excellent enantioselectivity to afford the corresponding optically active compounds. In this reaction, a unique temperature effect is observed. After optimizing the reaction conditions, this procedure is widely applicable to the practical preparation of both enantiomers of various optically active compounds with high ee.

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The substrate (±)-1 was prepared form 1-hexene in 3 steps; 1) OsO4, NMO, acetone-H2O; 2) TsCl, Bu2SnO, Et3N, CH2Cl2; [18] 3) Ac2O, pyridine. The details will be reported separately.

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In the screening test, we used the following enzymes: lipase type II, type VII (Sigma), lipase PS, lipase AY, lipase A, PLE-A, lipase d-360, lipase AK, lipase D (Amano Enzyme, Inc.), lipase OF (Meito Sangyo Co., Ltd), lipase (Nagase ChemteX Corp.), Novozym (NovoNordisk A/S). The hydrolysis of (±)-1 with lipase type II, lipase type VII, PLE-A or lipase OF proceeded with low enantioselectivity. The other enzymes did not catalyze the reaction.

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The absolute configurations of 1 and 2 were confirmed by comparing the obtained optical rotation value with the reported value: (R)-1, lit. [5a] [α]D 25 +13.4 (CHCl3), 86% ee; (S)-2, lit. [5a] [α]D 25 +4.2 (CHCl3), 66% ee.

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The ee of 1 was determined by HPLC analysis with CHIRALCEL AD-H (Daicel Chemical Industries, Ltd.); eluent: hexane-i-PrOH (90:10); flow rate: 0.5 mL min-1; t R = 18 (S) and 19.5 (R) min. A similar analysis of 2 was also performed with CHIRALCEL OD-H; eluent: hexane-i-PrOH (95:5); flow rate: 0.5 mL min-1; t R = 32 (R) and 35.5 (S) min.

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Compound (S)-1: 1H NMR (300 MHz, CDCl3): δ = 0.86 (t, J = 7.0 Hz, 3 H) 1.13-1.34 (m, 4 H), 1.46-1.65 (m, 2 H), 1.98 (s, 3 H), 2.46 (s, 3 H), 4.05 (dd, J 1 = 5.5 Hz, J 2 = 10.5 Hz, 1 H), 4.10 (dd, J 1 = 3.5 Hz, J 2 = 10.5 Hz, 1 H), 4.90-5.00 (m, 1 H), 7.35 (d, J = 8.5 Hz, 2 H), 7.79 (d, J = 8.5 Hz, 2 H). 13C NMR (75 MHz, CDCl3): δ = 13.7, 20.8, 22.2, 27.0, 30.0, 70.0, 70.9, 127.8, 130.0, 132.7, 145.0, 170.3. IR (neat): 3460, 2957, 2870, 1730, 1597, 1454, 1362, 1177 cm-1. MS (EI): m/z (%) = 314 (7.2) [M+], 254 (27), 228 (38), 198 (16), 172 (16), 143 (36), 129 (17), 91 (100), 82 (16). HRMS: m/z [M+] calcd for C15H22O5S: 314.1188; found: 314.1187.

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Compound (R)-2: 1H NMR (300 MHz, CDCl3): δ = 0.87 (t, J = 7.0 Hz, 3 H), 1.10-1.53 (m, 6 H), 2.19 (br s, 1 H), 2.45 (s, 3 H), 3.78-3.91 (m, 1 H), 3.84-3.94 (m, 1 H), 4.00-4.08 (m, 1 H), 7.36 (d, J = 8.5 Hz, 2 H), 7.80 (d, J = 8.5 Hz, 2 H). 13C NMR (75 MHz, CDCl3): δ = 13.8, 21.5, 22.4, 27.2, 32.2, 69.2, 73.9, 132.5, 144.9. IR (neat): 3539, 2955, 2872, 1599, 1454, 1360, 1177, 1098, 974 cm-1. MS (EI): m/z (%) = 242 (25), 172 (11), 155 (52), 139 (10) 107 (20), 91 (100), 87 (42). HRMS: m/z [M+] calcd for C13H20O4S: 272.1082; found: 272.1085.

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In the cases of 3a and 3e, the isolated yields of the compounds were low for the high volatility.