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Synlett 2007(1): 0087-0090  
DOI: 10.1055/s-2006-956498
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthetic Studies toward Amphidinolide H1: Segment C14-C26

Lisheng Deng, Zhixiong Ma, Yazhu Zhang, Gang Zhao*
Laboratory of Modern Synthetic Organic Chemistry, Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, P. R. of China
Fax: +86(21)64166128; e-Mail: zhaog@mail.sioc.ac.cn;
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Publication History

Received 25 August 2006
Publication Date:
20 December 2006 (online)

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Abstract

Stereoselective synthesis of the C14-C26 moiety of ­amphidinolide H1 is described. The key features of the approach ­include the convergent fragment assembly with a highly diastereoselective aldol reaction to establish the C18 stereochemistry and ­using commercially available chiral pool.

Key words

amphidinolide H1 - macrolide - aldol reaction - Wittig reaction - dihydroxylation

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Aldehyde 6: R f 0.41 (PE-EtOAc, 20:1); [α]D 26 +4.7 (c = 0.70, CHCl3). IR (film): 2962, 2169, 1729, 1250 cm-1. 1H NMR (300 MHz, CDCl3): δ = 9.78 (t, J = 2.1 Hz, 1 H), 2.96-3.03 (m, 1 H), 2.45-2.63 (m, 2 H), 1.23 (d, J = 7.2 Hz, 3 H), 0.13 (s, 9 H). 13C NMR (75 MHz, CDCl3): δ = 201.1, 109.2, 85.6, 49.8, 21.6, 20.9, 0.1. HRMS (EI): m/z [M]+ calcd for C9H16OSi: 168.0970; found: 168.0972.

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AD-mix-α*: OsO4·H2O (1 mol%), (DHQ)2PHAL (2 mol%), K3Fe(CN)6 (3 equiv), K2CO3 (3 equiv), NaHCO3 (3 equiv), and MeSO2NH2 (1 equiv). The reaction occurred at a significantly slower rate using commercially available AD-mix-α.

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Methyl ketone 11: R f 0.36 (PE-EtOAc, 15:1); [α]D 26 +3.1 (c = 0.76, CHCl3). IR (film): 2955, 1717, 1030 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.65-7.68 (m, 4 H), 7.26-7.42 (m, 6 H), 4.59-4.70 (m, 4 H), 4.06 (d, J = 5.1 Hz, 1 H), 3.82 (m, 1 H), 3.71 (m, 1 H), 3.42 (ddd, J = 5.1, 10.2, 10.5 Hz, 2 H), 3.32 (s, 3 H), 3.31 (s, 3 H), 2.18 (m, 3 H), 1.77-1.89 (m, 2 H), 1.41-1.48 (m, 1 H), 1.04 (s, 9 H), 1.01 (d, J = 6.9 Hz, 3 H), 0.89 (t, J = 7.8 Hz, 9 H), 0.52 (q, J = 7.8 Hz, 6 H). 13C NMR (75 MHz, CDCl3): δ = 208.4, 135.6, 133.5, 129.7, 127.7, 97.9, 97.4, 84.5, 81.8, 71.8, 67.9, 56.4, 56.2, 38.7, 31.4, 27.2, 26.9, 19.2, 15.6, 6.9, 5.0. HRMS (MALDI): m/z [M + Na]+ calcd for C35H58O7Si2Na: 669.3605; found: 669.3613.

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C14-C26 segment of 1: R f 0.48 (PE-EtOAc, 19:1); [α]D 26 +15.6 (c = 1.70, CHCl3). IR (film): 2956, 2163, 1719 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.65-7.67 (m, 4 H), 7.34-7.43 (m, 6 H), 4.58-4.64 (m, 4 H), 4.33-4.37 (m, 1 H), 4.13 (d, J = 4.2 Hz, 1 H), 3.82 (m, 1 H), 3.70 (m, 1 H), 3.51 (ddd, J = 5.1, 8.1, 10.2 Hz, 1 H), 3.30 (s, 3 H), 3.28 (s, 3 H), 2.90 (dd, J = 4.8, 10.8 Hz, 1 H), 2.60 (dd, J = 4.8, 10.8 Hz, 1 H), 2.42-2.50 (m, 1 H), 1.86 (m, 2 H), 1.54-1.65 (m, 3 H), 1.35-1.42 (m, 1 H), 1.15 (d, J = 9.6 Hz, 3 H), 1.04 (s, 9 H), 1.01 (d, J = 6.6 Hz, 3 H), 0.90 (t, J = 7.8 Hz, 9 H), 0.85 (s, 9 H), 0.54 (q, J = 7.8 Hz, 6 H), 0.13 (s, 9 H), 0.09 (s, 3 H), 0.05 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 209.0, 135.6, 133.5, 129.6, 127.7, 111.8, 97.6, 97.0, 84.4, 84.1, 82.1, 72.0, 68.1, 66.7, 56.4, 56.2, 46.3, 44.4, 38.5, 31.8, 26.9, 25.9, 23.1, 21.1, 19.2, 18.0, 16.1, 7.0, 5.1, 0.2, -4.4, -4.6. HRMS (ESI): m/z [M + Na]+ calcd for C50H88O8Si4: 951.5498; found: 951.5449.