Synlett 2006(8): 1177-1180  
DOI: 10.1055/s-2006-932487
LETTER
© Georg Thieme Verlag Stuttgart · New York

A New Synthesis of Tetrahydrofuran Fragment of Amphidinolides X and Y

Yile Chena, Jian Jina, Jinlong Wua, Wei-Min Dai*a,b
a Laboratory of Asymmetric Catalysis and Synthesis, Department of Chemistry, Zhejiang University, Hangzhou 310027, P. R. of China
Fax: +86(571)87953128; e-Mail: chdai@zju.edu.cn;
b Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, P. R. of China
Fax: +85223581594; e-Mail: chdai@ust.hk;
Further Information

Publication History

Received 29 November 2005
Publication Date:
10 March 2006 (online)

Abstract

A new synthesis of the tetrasubstituted tetrahydrofuran fragment of the marine secondary metabolites amphidinolides X and Y is described. The oxygenated chiral quaternary carbon was assembled by asymmetric dihydroxylation in high enantioselec­tivity and the tetrahydrofuran ring was constructed by an acid-catalyzed 5-endo ring-opening cyclization of the epoxide possessing a vinyl moiety.

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Spectroscopic data of 23: [α]D 20 -23.3 (c 0.60, CHCl3). IR (film): 2959, 2932, 1613, 1514, 1249, 1111, 1090, 1072, 1037 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.30-7.23 and 6.89-6.86 (A2B2, 4 H), 5.86 (ddd, J = 17.6, 10.8, 6.8 Hz, 1 H), 5.35 (dt, J = 17.2, 1.6 Hz, 1 H), 5.15 (dt, J = 10.4, 1.6 Hz, 1 H), 4.47 and 4.43 (ABq, J = 11.6 Hz, 2 H), 4.38 (dd, J = 6.4, 6.4 Hz, 1 H), 3.86-3.80 (m, 1 H), 3.80 (s, 3 H), 2.03 (dd, J = 12.8, 8.0 Hz, 1 H), 1.81 (dd, J = 13.2, 5.2 Hz, 1 H), 1.52-1.46 (m, 2 H), 1.40-1.32 (m, 2 H), 1.33 (s, 3 H), 0.92 (t, J = 7.2 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 159.1, 137.8, 130.2, 129.1 (2×), 116.2, 113.7 (2×), 84.0, 83.5, 83.0, 71.4, 55.2, 45.0, 42.3, 26.3, 17.8, 14.6. MS (+ESI): m/z (%) = 603 (80) [2 M + Na+], 313 (100) [M + Na+],
290 (10) [M+]. HRMS (+ESI): m/z calcd for C18H26O3Na+: 313.1780 [M + Na+]; found: 313.1776.

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Spectroscopic data of 24: [α]D 20 -52.2 (c 0.8, CHCl3, >96% ee); lit. (ref. 4) [α]D 20 -37.1 (c 1.0, CHCl3, 83% ee). 1H NMR (400 MHz, CDCl3): δ = 7.24 (d, J = 8.5 Hz, 2 H), 6.88 (d, J = 8.5 Hz, 2 H), 4.48 and 4.39 (ABq, J = 11.5 Hz, 2 H), 4.06 (ddd, J = 8.5, 5.0, 5.0 Hz, 1 H), 3.81 (s, 3 H), 3.80-3.74 (m, 3 H), 2.96 (br s, 1 H), 2.05 (dd, J = 12.5, 8.0 Hz, 1 H), 1.89-1.70 (m, 2 H), 1.78 (dd, J = 13.0, 5.0 Hz, 1 H), 1.50-1.45 (m, 2 H), 1.38-1.28 (m, 2 H), 1.31 (s, 3 H), 0.92 (t, J = 7.5 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 159.2, 129.8, 129.2 (2×), 113.9 (2×), 83.4, 83.2, 82.1, 71.5, 61.3, 55.2, 45.0, 42.3, 35.9, 26.3, 17.7, 14.5. MS (+ESI): m/z (%) = 639 (100) [2 M + Na+], 617 (53) [2 M + H+], 331 (100) [M + Na+], 309 (64) [M + H+]. HRMS (+ESI): m/z calcd for C18H28O4Na+: 331.1885 [M + Na+]; found: 331.1876.