Synlett 2003(13): 2009-2012  
DOI: 10.1055/s-2003-42039
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Novel 1,3-Central-to-Axial Chirality Induction Approach to Cyclooctadiene Lignans

Olivier Baudoin*, Anne Décor, Michèle Cesario, Françoise Guéritte
Institut de Chimie des Substances Naturelles, CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
Fax: +33(1)69077247; e-Mail: baudoin@icsn.cnrs-gif.fr;
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Publikationsverlauf

Received 16 July 2003
Publikationsdatum:
08. Oktober 2003 (online)

Abstract

The catalytic asymmetric synthesis of an axially chiral biaryl, potentially useful intermediate in the synthesis of dibenzocyclooctadiene lignans, has been performed. The key step consisted of a diastereoselective Suzuki coupling between a chiral benzylic alcohol and a sterically hindered boronic ester. The 1,3-induction from the benzylic stereocenter to the biaryl axis proceeded with very good diastereoselectivity.

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(+)-3: [α]D 23 +38.8 (c 1.1, CHCl3); HPLC (Chiracel OD, hexane-EtOH, 95:5, 1.0 mL/min) t R 7.8 min (minor enantiomer), 9.2 min (major enantiomer).

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Compound (-)-2d: mp 70 °C; [α]D 24 -21.4 (c 1.0, CHCl3); HPLC (C18 Symmetry column, H2O-CH3CN, 35:65, 1.0 mL/min) t R 16.6 min (diastereoisomer 1, 4%), 17.9 min (diastereoisomer 2, 96%); HPLC (Chiralpak AD, heptane-i-PrOH, 98:2, 1.0 mL/min) diastereoisomer 2: t R 10.8 min (enantiomer 1, 5%), 24.5 min (enantiomer 2, 95%), diastereoisomer 1: t R 11.4 min (enantiomer 1, 95%), 13.0 min (enantiomer 2, 5%). 1H NMR [300 MHz, (CD3)2CO]
δ = 1.15 (d, J = 6.3 Hz, 3 H), 3.23 (s, 3 H), 3.61 (s, 3 H), 3.74 (s, 3 H), 3.89 (s, 3 H), 4.15 (d, J = 12.0 Hz, 1 H), 4.21 (d,
J = 12.0 Hz, 1 H), 4.25 (q, J = 6.5 Hz, 1 H), 4.33 (d, J = 12.3 Hz, 1 H), 4.45 (d, J = 12.3 Hz, 1 H), 4.57 (s, 2 H), 6.04 (s, 1H), 6.06 (s, 1 H), 6.63 (s, 1 H), 6.98 (s, 1 H), 7.12 (s, 1 H), 7.20-7.32 (m, 5 H) (major diastereoisomer). 13C NMR [75.5 MHz, (CD3)2CO] δ = 23.9, 55.3, 56.2, 60.9, 61.0, 67.7, 70.8, 74.9, 96.7, 102.1, 105.9, 108.7, 111.0, 126.6, 127.7, 127.9, 128.5, 128.9, 133.5, 138.4, 140.7, 142.5, 147.2, 148.6, 151.2, 154.1 (major diastereoisomer). HRMS (ESI): m/z for [(M + Na)+] calcd for C28H32NaO8: 519.1995; found: 519.1982.

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Crystallographic data for 2d have been deposited with the Cambridge Crystallographic Data Center under number CCDC-203288.