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Synlett 2007(11): 1703-1706  
DOI: 10.1055/s-2007-984503
LETTER
© Georg Thieme Verlag Stuttgart · New York

3-Vinyl-2,5-dihydrofuran Derivatives via Enyne Metathesis

M. Mercedes Rodriguez-Fernandez, Sophie Vuong, Brigitte Renoux, Christophe Len*
Synthèse et Réactivité des Substances Naturelles, UMR 6514, FR 2703, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France
Fax: +33(5)49453501; e-Mail: christophe.len@univ-poitiers.fr;
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Publication History

Received 14 March 2007
Publication Date:
25 June 2007 (online)

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Abstract

Acyclic enynes having the alkyne moiety directly ­connected to the asymmetric carbon atom of an acetal were obtained in two steps. These reactive substrates were then subjected to ruthenium-catalyzed enyne metathesis to produce (5-ethoxy-4-­vinyl-2,5-dihydrofuran-2-yl)methanol derivatives in racemic and enantiomerically pure form. These products are useful glycosyl ­donors for the preparation of d4T analogues.

Key words

enyne - metathesis - carbohydrate - cyclization - furan

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RCEYM Reaction of rac -15 and rac -16 - Typical Procedure
The ruthenium catalyst 5 (3% mol) was dissolved in CH2Cl2 (26 mL) and ethylene gas was passed through the solution for 20 min. The enyne mixture of rac-15 and rac-16 (400 mg, 0.98 mmol) in CH2Cl2 (12 mL) was then added and the mixture was stirred under ethylene at 20 °C during 5 d. The volatiles were eliminated under reduced pressure and the residue was purified by flash chromatography (5% EtOAc in hexane) to give rac-cis-22 (100 mg, 25%) and rac-trans-22 (100 mg, 25%) in order of fractions eluted.

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Selected physico-chemical data for compound cis-12: R f = 0.50 (5% EtOAc-hexane). 1H NMR (300 MHz, CDCl3): δ = 7.71 (m, 4 H, Ph), 7.45 (m, 6 H, Ph), 6.48 (dd, 1 H, J = 12, 18 Hz, =CH), 6.18 (s, 1 H, H3), 5.87 (s, 1 H, H5), 5.46 (d, 1 H, J = 18 Hz, =CH), 5.23 (d, 1 H, J = 12 Hz, =CH), 4.80 (m, 1 H, J = 1 Hz, H2), 3.68 (m, 4 H, OCH 2CH3, CH2OSi), 1.23 (t, 3 H, J = 8 Hz, CH3), 1.06 (s, 9 H, 3 CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 138.9 (C4), 136.0 (Ph), 135.9 (Ph), 133.9 (C3), 133.8 (Ph), 130.4 (=CH), 128.1 (Ph), 118.0 (=CH2), 107.6 (C5), 85.7 (C2), 67.6 (CH2OSi), 62.6 (OCH2), 27.2 (CH3 of t-Bu), 19.6 (Cq of t-Bu), 15.8 (CH3) ppm. ESI-HRMS: m/z calcd [M + Na+]: 431.2018; found: 431.2034.

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Selected physico-chemical data for compound trans-12: R f = 0.20 (5% MeOH-CH2Cl2). 1H NMR (300 MHz, CDCl3): δ = 7.65 (m, 4 H, Ph), 7.38 (m, 6 H, Ph), 6.43 (m, 1 H, J = 12, 18Hz, =CH), 5.98 (s, 1 H, H3), 5.96 (d, 1 H, J = 4 Hz, H5), 5.43 (d, 1 H, J = 18, =CH), 5.24 (d, 1 H, J = 12 Hz, =CH), 4.90 (m, 1 H, H2), 3.72 (m, 4 H, OCH 2CH3, CH2OSi), 1.26 (t, 3 H, J = 8 Hz, CH3), 1.04 (s, 9 H, 3 CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 138.8 (C4), 136.0 (Ph), 133.9 (Ph), 130.6 (C3), 130.0 (Ph), 129.0 (=CH), 128.1 (Ph), 118.0 (=CH2), 107.6 (C5), 85.6 (C2), 66.6 (CH2OSi), 62.1 (OCH2), 27.2 (CH3 of t-Bu), 19.6 (Cq of t-Bu), 15.8 (CH3). ESI-HRMS: m/z calcd [M + Na+]: 431.2018; found: 431.2025.