Download PDF
Synlett 2002(9): 1496-1499
DOI: 10.1055/s-2002-33527
LETTER
© Georg Thieme Verlag Stuttgart · New York

Syntheses of the D-, E-, F-, and I-Ring Parts of Ciguatoxin by a Common Strategy Starting from Tri- O -acetyl- d -glucal

Kenshu Fujiwara*a, Yasuhito Koyamaa, Eriko Doia, Ken Shimawakia, Yuko Ohtaniuchia, Atsushi Takemura, Shin-ichiro Soumaa, Akio Murai*a,b
Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
Fax: +81(11)7062714; e-Mail: fjwkn@sci.hokudai.ac.jp;
Present address: 6-14-44 Asabu-cho, Kita-ku, Sapporo 001-0045, Japan
Fax: +81(11)7476963; e-Mail: amurai@rmail.plala.or.jp;
Further Information

Publication History

Received 29 May 2002
Publication Date:
17 September 2002 (online)

    Permissions and Reprints All articles of this category

Abstract

Chiral medium-sized monocyclic ethers corresponding to the D-, E-, F-, and I-ring parts of ciguatoxin have been synthesized from tri-O-acetyl-d-glucal through a common synthetic route involving ring-closing olefin metathesis.

Key words

Heterocycles - stereoselective synthesis - natural products - ethers - metathesis

16

Representative data for 2: a colorless oil; [α]D 22 +23.3 (c, 0.06, CHCl3); 1H NMR (300 MHz, CDCl3), δ 7.48 (2 H, m, Ph), 7.36 (3 H, m, Ph), 5.77 (2 H, m, H4, H5), 5.30 (1 H, s, acetal), 4.53 (1 H, dd, J = 12, 4.3 Hz, H8a), 4.31-4.17 (4 H, m, H1eq, H3, H6, H8b), 3.64 (1 H, t, J = 10 Hz, H1ax), 3.60-3.56 (1 H, m, H7), 3.52 (1 H, dt, J = 10, 4.8 Hz, H2), 2.92 (1 H, d, J = 5.7 Hz, 6-OH), 1.24 (9 H, s, t-Bu); IR (film): 3487, 2971, 2860, 1729, 1481, 1456, 1399, 1287, 1167, 1115, 1032, 977, 752, 698 cm-1; HR-EIMS, calcd for C20H26O6 (M)+: 362.1729, found: 362.1722.

19

Representative data for 3: a colorless oil; [α]D 21 -9.2 (c 0.29, CHCl3); 1H NMR (400 MHz, CDCl3, 55 °C), δ 7.28-7.48 (5 H, m, Ph), 5.74-5.82 (2 H, m, H5, H6), 5.40 (1 H, s, acetal), 4.52 (1 H, dd, J = 4.3, 10.3 Hz, H1eq), 3.77 (1 H, dd, J = 1.8, 10.6 Hz, H10a), 3.62-3.70 (2 H, m, H3, H8), 3.57 (1 H, dt, J = 4.3, 10.3 Hz, H2), 3.50 (1 H, t, J = 10.3 Hz, H1ax), 3.44 (1 H, dd, J = 7.7, 10.6 Hz, H10b), 3.32 (1 H, dt, J = 1.8, 7.7 Hz, H9), 2.68-2.80 (1 H, m, H4a), 2.44-2.58 (2 H, m, H7a, H4b), 2.28-2.43 (1 H, m, H7b), 0.91 (9 H, s, TBS), 0.90 (9 H, s, TBS), 0.098 (3 H, s, TBS), 0.070 (3 H, s, TBS), 0.066 (3 H, s, TBS), 0.049 (3 H, s, TBS); IR(film): 2955, 2928, 2856, 1471, 1462, 1389, 1361, 1294, 1258, 1213, 1148, 1103, 1027, 977, 836, 811, 776, 747, 665 cm-1; HR-FDMS, calcd for C29H51O5Si2 (M + H)+: 535.3298, found: 535.3275.

23

Representative data for 4: a colorless oil; [α]D 25 +13.3 (c 0.15, CHCl3); 1H NMR [400 MHz, C6D6-CDCl3 (1:1)], δ 7.66-7.72 (4 H, m, Ph), 7.51-7.47 (2 H, m, Ph), 7.33-7.15 (9 H, m, Ph), 5.29 (1 H, s, acetal), 4.08-4.17 (1 H, m, H1eq), 3.75 (1 H, dd, J = 10.5, 5.4 Hz, H9a), 3.69 (1 H, dd, J = 10.5, 5.9 Hz, H9b), 3.50-3.59 (1 H, m, H7), 3.42-3.50 (1 H, m, H3), 3.35-3.41 (2 H, m, H1ax, H2), 3.26 (1 H, brdt, J = 8.9, 5.5 Hz, H8), 2.28 (1 H, m, 7-OH), 1.91 (1 H, brdd, J = 13.8, 3.5 Hz, H4a), 1.62-1.64 (1 H, m, H5), 1.53-1.62 (3 H, m, H4b, H6), 1.09 (9 H, s, t-Bu), 1.00 (3 H, d, J = 7.1 Hz, 5-Me); IR(film): 3490, 3071, 3047, 2928, 2857, 1589, 1455, 1428, 1391, 1372, 1292, 1215, 1112, 1029, 916, 823, 744, 701, 615 cm-1; HR-EIMS, calcd for C29H33O5Si (M - t-Bu)+: 489.2097, found: 489.2105.