Compound 19

(4R,6S,7E,10S,12S,14R)-12-(tert-Butyldimethylsilyloxy)-10,14-di(methoxymethoxy)-4,6-[(S)-methylmethylene­dioxy]-7-pentadecen-2-one

From: Total synthesis of marinomycin A using salicylate as a molecular switch to mediate dimerization

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InChIKey WEUDJIHCORYWIX-CNINBBRCSA-N

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Hoveyda–Grubbs second generation catalyst (0.20 g, 0.32 mmol) dissolved in CH2Cl2 (20 mL) was added to a stirred solution of the homoallyl ether 4 (2.0 g, 5.31 mmol) and syn-1,3-dioxane 5 (2.94 g, 15.93 mmol) in CH2Cl2 (20 mL) at room temperature. The resulting mixture was heated at reflux for ca. 53 hours then concentrated in vacuo to afford the crude product. Purification by flash chromatography (silica gel, 10–50% diethyl ether in petroleum ether) furnished the E-alkene 19 (2.26 g, 80%) as a colorless oil: Rf = 0.15 (TLC, 3:7 diethyl ether/petroleum ether); [α]D24 +2.0 (c = 1.00, CHCl3); 1H-NMR (500 MHz, CDCl3) δ 5.74–5.68 (m, 1H), 5.54 (dd, J = 15.6, 6.1 Hz, 1H), 4.76 (q, J = 5.1 Hz, 1H), 4.66 (d, A of AB, JAB = 6.8 Hz, 1H), 4.65 (d, A of AB, JAB = 6.3 Hz, 1H), 4.64 (d, B of AB, JAB = 6.3 Hz, 1H), 4.63 (d, B of AB, JAB = 6.9 Hz, 1H), 4.15–4.10 (m, 2H), 3.90–3.85 (m, 1H), 3.78–3.68 (m, 2H), 3.36 (s, 6H), 2.78 (dd, A of ABX, JAB = 16.4 Hz, JAB = 7.2 Hz, 1H), 2.48 (dd, B of ABX, JAB = 16.4 Hz, JBX = 5.4 Hz, 1H), 2.29 (app. t, J = 6.3 Hz, 2H), 2.19 (s, 3H), 1.73 (ddd, A of ABXY, JAB = 13.7 Hz, JAX = 7.5 Hz, JAY = 6.1 Hz, 1H), 1.66–1.50 (m, 4H), 1.36 (app. dt, B of ABX2, JAB = 13.0, JAX = 11.4 Hz, 1H), 1.31 (d, J = 5.1 Hz, 3H), 1.18 (d, J = 6.2 Hz, 3H), 0.87 (s, 9H), 0.06 (s, 3H), 0.06 (s, 3H); 13C-NMR (125 MHz, CDCl3) δ 206.72 (e), 132.38 (o), 128.46 (o), 98.61 (o), 95.87 (e), 95.36 (e), 76.46 (o), 74.80 (o), 72.18 (o), 71.18 (o), 67.41 (o), 55.73 (o), 55.46 (o), 49.53 (e), 46.01 (e), 43.07 (e), 38.04 (e), 36.61 (e), 31.31 (o), 26.06 (o), 21.27 (o), 21.20 (o), 18.18 (e), −3.85 (o), −3.92 (o); IR (neat) 2930 (w), 2881 (w), 2857 (w), 1719 (w), 1375 (w), 1255 (w), 1212 (w), 1130 (m), 1099 (m), 1034 (s), 918 (m), 836 (m), 775 (m) cm−1; HRMS (ESI, [M+Na]+) calcd for C27H52O8NaSi 555.3329, found 555.3325.

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