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Synlett 2003(11): 1698-1700
DOI: 10.1055/s-2003-40986
LETTER
© Georg ThiemeVerlag Stuttgart ˙ New York

Total Synthesis of Marine OxylipinsConstanolactone A and B

Jörg Pietruszka*, Thorsten Wilhelm
Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring55, 70569 Stuttgart, Germany
Fax: +49(711)6854269; e-Mail: joerg.pietruszka@po.uni-stuttgart.de;
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Publication History

Received 5 June 2003
Publication Date:
05 August 2003 (online)

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Abstract

A short, high-yielding synthesis of the marine oxylipins constanolactoneA and B was reported. Starting from cinnamyl alcohol (3), the cylopropyl lactone moiety 2 was obtained in 28% yield (11steps). The second coupling partner, vinyl iodide 1,was isolated in 7 steps and 32% yield. Chromium mediatedaddition yielded the natural products as a 2:1 mixture (74%).

Key words

natural products - total synthesis - asymmetricsynthesis - cyclopropane - ozonolysis

17

Spectroscopic data of the key intermediate 15: [α]D 20 = 57(c 0.96, CHCl3). IR(film): ν = 2957(br OH), 2861, 2622, 1729 (C=O), 1718 (C=O) cm-1.HRMS (CI, 70 eV) for [M + H+] (C9H13O4):Calcd 185.0755. Found: 185.0808. 1H NMR (500MHz, CDCl3): δ = 1.09 (ddd, 3 J = 8.5 Hz, 3 J = 6.8 Hz, 2 J 4a,4b = 4.7Hz, 1 H, 4-Ha), 1.29 (ddd, 3 J = 9.4 Hz, 3 J = 4.7 Hz, 2 J 4b,4a = 4.6Hz, 1 H, 4-Hb), 1.72 (1 H, dddd, 2 J 5 ′ a,5 ′ b = 13.8 Hz, 3 J 5 ′ a,4 ′ a = 11.7Hz, 3 J 5 ′ a,6 ′ = 10.6 Hz, 3 J 5 ′ a,4 ′ b = 5.0Hz, 5′-Ha), 1.75-1.79 (2 H, m c , 2-H, 3-H), 1.84 (ddddd, 2 J 4 ′ a,4 ′ b = 13.0 Hz, 3 J 4 ′ a,5 ′ a ′ = 11.7 Hz, 3 J 4 ′ a,3 ′ a = 9.0 Hz, 3 J 4 ′ a,3 ′ b = 7.0Hz, 3 J 4 ′ a,5 ′ b = 4.7Hz, 1 H, 4′-Ha), 1.97 (ddddd, 2 J 4 ′ b,4 ′ a = 13.0 Hz, 3 J 4 ′ b,3a ′ = 7.1Hz, 3 J 4 ′ b,3 ′ b = 5.0Hz, 3 J 4 ′ b,5 ′ a = 5.0Hz, 3 J 4 ′ b,5 ′ b = 4.7Hz, 1 H, 4′-Hb), 2.05 (1 H, ddddd, 2 J 5 ′ b,5 ′ a = 13.8Hz, 3 J 5 ′ b,4 ′ b = 4.7Hz, 3 J 5 ′ b,4 ′ a = 4.7Hz, 3 J 5 ′ b,6 ′ = 3.3Hz, 4 J 5 ′ b,3 ′ b = 1.3Hz, 5′-Hb), 2.48 (ddd, 2 J 3 ′ a,3 ′ b = 17.9 Hz, 3 J 3 ′ a,4 ′ a = 9.0Hz, 3 J 3 ′ a,4 ′ b = 7.1Hz, 3′-Ha), 2.59 (dddd, 2 J 3 ′ b,3 ′ a = 17.9 Hz, 3 J 3 ′ b,4a ′ = 7.0 Hz, 3 J 3 ′ b,4b ′ = 5.0 Hz, 4 J 3 ′ b,5 ′ b = 1.3Hz, 1-H, 3′-Hb), 3.91 (1 H, ddd, 3 J 6 ′ ,5 ′ b = 10.6 Hz, 3 J 6 ′ ,3 = 6.7Hz, 3 J 6 ′ ,5 ′ b = 3.3Hz, 6′-H), 10.74 (1 H, b, COOH). 13CNMR (125 MHz, CDCl3): δ = 12.1 (C-4),17.8 (C-3), 18.3 (C-4′), 26.6 (C-2), 27.8 (C-5′),29.4 (C-3′), 80.9 (C-6′), 171.4 (C-2′),179.0 (COOH).