C1(C)C=CC=CC=1.CSC.B.[Br:12][CH2:13][CH2:14][CH:15]=[C:16]1[C:22]2[CH:23]=[CH:24][CH:25]=[CH:26][C:21]=2[CH2:20][C:19](=[O:27])[C:18]2[CH:28]=[CH:29][CH:30]=[CH:31][C:17]1=2.C(=O)(O)[O-].[Na+]>CO.O1CCCC1>[Br:12][CH2:13][CH2:14][CH:15]=[C:16]1[C:22]2[CH:23]=[CH:24][CH:25]=[CH:26][C:21]=2[CH2:20][C@H:19]([OH:27])[C:18]2[CH:28]=[CH:29][CH:30]=[CH:31][C:17]1=2
In a dry 40 mL vial with a septum cap, R-CBS catalyst, 1 M in toluene (3.98 mL, 3.98 mmol), 2.0 M borane-dimethyl sulfide in tetrahydrofuran (1.69 mL, 3.37 mmol), and 10 mL dry tetrahydrofuran were premixed. The premix was cooled to −20° C. in an acetonitrile/dry ice bath. A tetrahydrofuran solution of 5-(3-bromo-propylidene)-5,11-dihydro-dibenzo[a,d]cyclohepten-10-one (6) (1.00 g, 3.06 mmol) which had been stored over molecular sieves was then added dropwise. The reaction was allowed to slowly come to room temperature over ˜90 minutes. When complete, the reaction was cooled to 0° C. and 1 mL methanol added to quench the reaction. After 15 minutes of further stirring, 1 mL saturated sodium bicarbonate was added. The reaction mixture was then concentrated under reduced pressure and the residue separated between water (50 mL) and dichloromethane (50 mL). The organic layer was then separated, evaporated, and the crude residue was purified by silica gel chromatography using a 5-25% hexanes:ethyl acetate gradient. 0.90 g (89%) (S)-5-(3-Bromo-propylidene)-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-10-ol (7a) was obtained as a faintly yellow oil. ESI MS m/z 623.3 (2(M−H2O)+H)+.
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