Boron tribromide → [1R*,8S*,9aR*]1-Amino-5,6-dihydroxy-8-phenyl-2,3,7,8,9,9a-hexahydrophenalene hydrobromide

Participants

Reaction Steps

To a solution of 0.4 g (1.2 mmol) of [1R*,8S*,9aR*]1-amino-5,6-dimethoxy-8-phenyl-2,3,7,8,9,9a-hexahydrophenalene in 9 mL of methylene chloride at -78° C., was added dropwise 4.4 mL (4.4 mmol) of a 1M solution of boron tribromide in methylene chloride. The reaction mixture was warmed to ambient temperature for 1 hour and cooled to -78° C. and the reaction was quenched by the addition of 5 mL of methanol. The reaction was allowed to lo warm to ambient temperature and stirred for 1 hour. The solvent was removed in vacuo. Methanol (5 mL) was added and the solution was concentrated to remove methyl borate by azeotropic distillation. The title compound was obtained (0.32 g, 69% yield) after recrystallization from ethanol/diethyl ether as a white solid; DCI MS: 279 (M+H)+, 296 (M-NH4)+. 1H NMR (d6 -DMSO) δ: 1.4-1.6 (m, 1H), 1.7-1.9 (m, 1H), 2.1-2.2 (m, 1H), 2.2-2.3 (m, 1H), 2.4-2.5 (m, 2H), 2.7-3.2 (m, 5H), 6.41 (s, 1H), 7.2-7.4 (m, 5H), 8.0 (br s, 5H). Analysis calculated for C19H22BrNO2 +0.5 H2O: C, 59.23; H, 5.99; N, 3.64. Found: C, 59.26; H, 5.86; N, 3.59.

Provenance & Evidence