Compound A12
2-Bromobenzyl 3-((3aS,5aS,6R,9aS,9bS)-3a,6-dimethyl-3,5,7-trioxododecahydro-1H-cyclopenta[a]naphthalen-6-yl)propanoate
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InChIKey HYJSOYTULKMLIR-LDVVLKKCSA-N
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Acid A8 (215 mg, 0.672 mmol) was dissolved in anhydrous dichloromethane (7 mL) and cooled to 0 °C before 2-bromobenzyl alcohol (126 mg, 0.672 mmol) was added. N,N’-Dicyclohexylcarbodiimide (125 mg, 0.605 mmol) and 4-dimethylaminopyridine (8 mg, 0.067 mmol) were added to the reaction which was allowed to warm to room temperature and stirred for 21 hours. The reaction contents were then directly passed through a half-inch plug of silica gel eluting with ethyl acetate. The product was further purified by flash chromatography by using 5:1 to 1:1 hexanes/ethyl acetate to give 208.3 mg ester A12 (63% yield) as a white amorphous solid. 1H NMR (CDCl3, 500 MHz): δ 7.55 (dd, J = 7.9, 1.2 Hz, 1H), 7.41 (dd, J = 7.7, 1.7 Hz, 1H), 7.31 (td, J = 7.5, 1.2 Hz, 1H), 7.17 (td, J = 7.7, 1.8 Hz, 1H), 5.14 (m, 2H), 2.66 - 2.53 (m, 2H), 2.48 (d, J = 13.2 Hz, 1H), 2.42 - 2.10 (m, 11H), 1.90 (ddd, J = 12.5, 10.5, 5.9 Hz, 1H), 1.71 (tt, J = 12.5, 9.2 Hz, 1H), 1.53 - 1.36 (m, 1H), 1.34 (s, 3H), 0.89 (s, 3H). 13C NMR (CDCl3, 125 MHz): δ 216.7, 212.0, 207.2, 173.4, 135.6, 133.0, 130.2, 129.9, 127.7, 123.6, 66.0, 57.7, 50.6, 50.1, 50.0, 49.9, 37.2, 36.1, 35.7, 30.3, 29.9, 28.8, 21.8, 20.5, 15.0. HRMS(ESI): m/z calc. for C25H30O5Br [M+H]+: 489.1277, found: 489.1274.
