Synlett 2009(20): 3271-3274  
DOI: 10.1055/s-0029-1218360
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Enantiopure Dicyclopropanes from trans-Cyclohexadienediols

Tobias Hausmann, Jörg Pietruszka*
Institut für Bioorganische Chemie, Heinrich-Heine Universität Düsseldorf im Forschungszentrum Jülich, Stetternicher Forst Geb. 15.8, 52426 Jülich, Germany
Fax: +49(2461)616196; e-Mail: j.pietruszka@fz-juelich.de;
Further Information

Publication History

Received 2 October 2009
Publication Date:
11 November 2009 (online)

Abstract

The protecting-group-induced highly regio- and enantioselective syntheses of dicyclopropanated building blocks starting from microbially produced trans-2,3-dihydroxy-2,3-dihydrobenzoic acid are described. Key to the success was a two-step cycloaddition-photolysis sequence for the second cyclopropanation. The structure of the unexpected inverse [3+2]-cycloaddition product of the 1,3-dipolar cycloaddition was verified.

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Crystallographic data for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-745676 (4) and 745677 (10). Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: +44 (1223)336033;
E-mail: deposit@ccdc.cam.ac.uk].

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[3+2]-Dipolar Cycloaddition; General Procedure
A freshly prepared solution of CH2N2 [¹7] in Et2O (0.4 M, 10 equiv) was added to a solution of cyclopropane 4 (1 equiv) in dry Et2O (6 mL/equiv). After 3 d in the dark at r.t. and without stirring, complete conversion (as judged by TLC) was detected. The excess CH2N2 was destroyed, and the mixture was concentrated under reduced pressure. Flash column chromatography on silica gel (eluent: PE-EtOAc, gradient 85:15 to 60:40), provided 9a (84%) as colourless crystals and 9b (15%) as colourless oil.
Selected Data of Regioisomer 9a
¹H NMR (600 MHz, CDCl3): δ = 0.67 (m, 1 H, 4-Ha), 0.67 (m, 1 H, 3b-H), 0.76 (m, 1 H, 4-Hb), 1.12 (dddd, ³ J 4a,4b = 4.4 Hz, ³ J 4a,4-a = 5.4 Hz, ³ J 4a,3b = 8.5 Hz, ³ J 4a,4-b = 8.5 Hz, 1 H, 4a-H), 1.30 (s, 3 H, 6-CH3), 1.36 (s, 3 H, 7-CH3), 2.59 (dd, ³ J 3a,3-a = 1.3 Hz, ³ J 3a,3-b = 7.6 Hz, 1 H, 3a-H), 3.21 (s, 3 H, 6-OCH3), 3.30 (s, 3 H, 7-OCH3), 3.66 (s, 3 H, CO2CH3), 3.90 (dd, ³ J 4b,4a = 4.4 Hz, ³ J 4b,8a = 10.5 Hz, 1 H, 4b-H), 4.36 (dd, ² J 3-b,3-a = 17.5 Hz, ³ J 3-b,3a = 7.6 Hz, 1 H, 3-Hb), 4.37 (d, ³ J 8a,4b = 10.5 Hz, 1 H, 8a-H), 4.78 (dd, ² J 3-a,3-b = 17.5 Hz, ³ J 3-a,3a = 1.3 Hz, 1 H, 3-Ha) ppm. ¹³C NMR (151 MHz, CDCl3): δ = 7.6 (C-4), 14.7 (C-4a), 16.2 (C-3b), 18.0 (7-CH3), 18.1 (6-CH3), 37.6 (C-3a), 48.0 (6-OCH3), 48.4 (7-OCH3), 53.0 (CO2 CH3), 63.7 (C-4b), 66.5 (C-8a), 84.9 (C-3), 96.9 (C-8b), 100.0 (C-6), 100.9 (C-7), 169.0 (CO2CH3) ppm.
Selected Data of Regioisomer 9b ¹H NMR (600 MHz, CDCl3): δ = 0.78 (dddd, ² J 8-a,8-b = 6.3 Hz, ³ J 8-a,7b = 8.2 Hz, ³ J 8-a,8a = 9.4 Hz, 4 J 8-a,7a = 0.6 Hz, 1 H, 8-Ha), 1.00 (ddd, ² J 8-b,8-a = 6.3 Hz, ³ J 8-b,7b = 5.2 Hz, ³ J 8-b,8a = 6.3 Hz, 1 H, 8-Hb), 1.17 (s, 3 H, 5-CH 3), 1.20 (dddd, ² J 7b,7a = 3.8 Hz, ³ J 7b,8-b = 5.2 Hz, ³ J 7b,8-a = 8.2 Hz, ³ J 7b,8a = 8.7 Hz, 1 H, 7b-H), 1.24 (s, 3 H, 6-CH 3), 1.86 (dddd, ³ J 8a,8b = 1.2 Hz, ³ J 8a,8-b = 5.4 Hz, ³ J 8a,7b = 8.7 Hz, ³ J 8a,8-a = 9.4 Hz, 1 H, 8a-H), 3.16 (s, 3 H, 5-OCH3), 3.18 (s, 3 H, 6-OCH3), 3.66 (s, 3 H, CO2CH3), 3.66 (ddd, ³ J 7a,7b = 3.8 Hz, ³ J 7a,3b = 10.4 Hz, 4 J 7a,8-a = 0.6 Hz, 1 H, 7a-H), 4.25 (d, ³ J 3b,7a = 10.4 Hz, 1 H, 3b-H), 4.86 (dd, ² J 3-b,3-a = 19.4 Hz, 4 J 3-b,8b = 3.0 Hz, 1 H, 3-Hb), 5.03 (ddd, ³ J 8b,8a = 1.2 Hz, 4 J 8b,3-a = 1.1 Hz, 4 J 8b,3-b = 3.0 Hz, 1 H, 8b-H), 5.13 (dd, ² J 3-a,3-b = 19.4 Hz, 4 J 3-a,8b = 1.1 Hz, 1 H, 3-Ha) ppm. ¹³C NMR (151 MHz, CDCl3): δ = 5.3 (C-8), 13.5 (C-8a), 14.4 (C-7b), 17.7 (6-CH3), 17.9 (5-CH3), 48.1 (5-OCH3), 48.2 (6-OCH3), 50.0 (C-3a), 53.0 (CO2 CH3), 63.9 (C-7a), 65.7 (C-3b), 82.1 (C-3), 92.3 (C-8b), 99.8 (C-6), 100.2 (C-5), 173 (CO2CH3) ppm.