Compound 20b
(2E,5S,7S,8Z,11S,13S,15R)-Ethyl 13-(tert-butyldimethylsilyloxy)-11,15-di(methoxymethoxy)-3-methyl-5,7-[(S)-methylmethylenedioxy]hexadeca-2,8-dienate
From: Total synthesis of marinomycin A using salicylate as a molecular switch to mediate dimerization
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InChIKey OJTFIUZFYQZWEX-UZEBIVQQSA-N
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Compound 20b was prepared by the method outlined for compound 20a. Rf = 0.53 (TLC, petroleum ether/Et2O, 1:1); [α]D20 −25.9 (c = 0.90, CHCl3); 1H-NMR (500 MHz, CDCl3) δ 5.73 (s, 1H), 5.69 (dt, J = 15.2, 7.6 Hz, 1H), 5.54 (dd, J = 15.5, 6.3 Hz, 1H), 4.69 (q, J = 5.1 Hz, 1H), 4.66 (d, J = 6.9 Hz, 1H), 4.65−4.61 (m, 3H), 4.12 (q, J = 7.2 Hz, 2H), 4.09−4.06 (m, 1H), 3.90−3.84 (m, 2H), 3.77−3.67 (m, 2H), 3.36 (s, 3H), 3.35 (s, 3H), 3.09 (dd, A of ABX, JAB = 12.7 Hz, JAX = 4.0 Hz, 1H), 2.50 (dd, B of ABX, JAB = 12.7 Hz, JBX = 8.4 Hz, 1H), 2.29 (app. t, J = 6.2 Hz, 2H), 1.97 (d, J = 1.2 Hz, 3H), 1.72 (ddd, A of ABXY, JAB = 13.7 Hz, JAX = 7.4 Hz, JAY = 6.2 Hz, 1H), 1.66−1.61 (m, 2H), 1.56 (ddd, J = 14.1, 7.2, 4.8 Hz, 1H), 1.52 (ddd, B of ABXY, JAB = 13.8 Hz, JBX = 6.7 Hz, JBY = 5.8 Hz, 1H), 1.42 (app. dt, J = 12.9, 11.3 Hz, 1H), 1.31 (d, J = 5.1 Hz, 3H), 1.26 (t, J = 7.2 Hz, 3H), 1.18 (d, J = 6.2 Hz, 3H), 0.87 (s, 9H), 0.06 (s, 6H); 13C-NMR (125 MHz, CDCl3) δ 166.49 (e), 158.21 (e), 132.67 (o), 128.21 (o), 117.38 (o), 98.43 (o), 95.91 (e), 95.37 (e), 76.71 (o), 76.42 (o), 74.88 (o), 71.19 (o), 67.41 (o), 59.67 (e), 55.73 (o), 55.47 (o), 46.02 (e), 43.11 (e), 39.55 (e), 38.11 (e), 36.68 (e), 27.45 (o), 26.07 (o), 26.05 (o), 21.27 (o), 18.18 (e), 14.46 (o), −3.86 (o), −3.91 (o); IR (neat) 2929 (w), 2886 (w), 2857 (w), 1712 (w), 1646 (w), 1443 (w), 1375 (w), 1335 (w), 1256 (w), 1213 (m), 1147 (m), 1126 (m), 1097 (m), 1033 (s), 947 (m), 918 (m), 835 (m), 774 (m) cm−1; HRMS (ESI, [M+Na]+) calcd for C31H58O9NaSi 625.3748, found 625.3756.
