Boron tribromide → (1R,10R,11S,16S)-1,11,15,15-tetramethyl-8-oxatetracyclo[8.8.0.02,7.011,16]octadeca-2,4,6-triene-3,5-diol

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Reaction Steps

To a solution of (1R,10R,11S,16S)-1,11,15,15-tetramethyl-3,5-bis(propan-2-yloxy)-8-oxatetracyclo[8.8.0.02,7.011,16]octadeca-2,4,6-triene (Compound No. 49) (0.20 g, 0.48 mmol) in CH2Cl2 (10 mL), cooled to 0° C., a 1 M BBr3 solution in CH2Cl2 (1.8 mL, 1.8 mmol) was added dropwise. The ice bath was removed and the reaction was stirred at room temperature for 5 h. The reaction was quenched with MeOH (10 mL) and concentrated. This quench/concentration step was repeated 5 times. Purification by column chromatography on silica gel (Hexanes/EtOAc, 4:1) gave (1R,10R,11S,16S)-1,11,15,15-tetramethyl-8-oxatetracyclo[8.8.0.02,7.011,16]octadeca-2,4,6-triene-3,5-diol (Compound No. 50) (0.08 g, 50%) as a tan solid. 1H NMR (CDCl3): δ 5.85 (d, 1H), 5.75 (d, 1H), 4.62 (s, 1H), 4.42 (s, 1H), 4.25 (m, 1H), 3.97 (t, 1H), 3.00 (m, 1H), 1.75-1.40 (m, 7H), 1.38 (s, 3H), 1.23-1.00 (m, 2H), 0.98-0.80 (m, 5H), 0.78 (s, 3H), 0.73 (s, 3H). MS m/z 331 (C21H30O3+H+).

Provenance & Evidence