Compound G8
(1S,4R,5bR,8S,10aS,11S,11aS,13R)-8,13-Dihydroxy-1-methyl-9-methylene-2-oxo-2,4,5b,6,7,8,9,10,11,11a-decahydro-1H-1,4:8,10a-dimethanoazuleno[1,2-d]oxepine-11-carboxylic acid
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InChIKey SLSYEBAZQRZQID-MLHXFEACSA-N
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Compound G8 was prepared according to the modified procedure of Henderson, J. H. & Graham, H. D. (Henderson, J. H. & Graham, H. D.A possible mechanism for biological and chemical activity of gibberellic acid. Nature 193, 1055-1056 (1962).) Gibberellic acid (1.002 g, 2.89 mmol) and sodium hydroxide (954 mg, 23.9 mmol) were dissolved in water (500 mL) in a round bottom flask. After stirring at room temperature for 1.5 hours, the reaction was acidified to pH 3 and extracted with ethyl acetate (5x). The organic layers were dried over magnesium sulfate and concentrated to afford known compound G8 as a white solid (771 mg, 77% yield). 1H NMR (d6-acetone, 500 MHz): δ 5.80 (dt, J = 5.2, 2.6 Hz, 1H), 5.10 - 5.06 (m, 1H), 4.93 - 4.90 (m, 1H), 4.70 (t, J = 5.3 Hz, 1H), 4.28 (d, J = 5.3 Hz, 1H), 3.33 (dd, J = 6.1, 2.7 Hz, 1H), 2.81 (br s, 1H), 2.68 (dt, J = 16.4, 3.0 Hz, 1H), 2.61 - 2.55 (m, 1H), 2.44 (d, J = 6.1 Hz, 1H), 2.33 - 2.24 (m, 1H), 1.99 - 1.89 (m, 1H), 1.77 - 1.62 (m, 3H), 1.51 (dd, J = 11.0, 3.1 Hz, 1H), 1.49 - 1.42 (m, 1H), 1.34 (ddd, J = 10.9, 2.8, 1.1 Hz, 1H), 1.16 (s, 3H). 13C NMR (d6-acetone, 125 MHz): δ 177.5, 176.0, 155.7, 151.9, 114.6, 106.3, 79.0, 75.8, 74.9, 49.9, 49.8, 49.6, 49.1, 46.7, 46.3, 39.9, 38.6, 19.4, 17.4. HRSM(ESI): m/z calc. for C19H22O6Na [M+Na]+: 369.1314, found: 369.1317.
