Lithium Bromide → 1-(2-Chloro-9,10-dihydro-9,10-methanoanthracen-9-ylmethyl)-4-(1,1-dimethylethyl)piperidin-4-ol

Participants

Reaction Steps

To a cooled solution (-78° C.) of lithium bromide (770 mg, 8.87 mmol, 1.5 eq) in tetrahydrofuran (60 mL) under nitrogen was added recently titrated t-butyllithium (1.7M in pentane, 4.20 mL, 7.10 mmol, 1.2 eq). The resulting strong yellow color was quenched on the addition of a 1-(2-chloro-9,10-dihydro-9,10-methanoanthracen-9-ylmethyl)-4-piperidinone (described in example 1m) (2.00 g, 5.92 mmol) solution in tetrahydrofuran (15 mL). The reaction was warmed to room temperature over 10 min and quenched with water (50 mL). The aqueous phase was extracted with ethyl acetate (3×60 mL). Combined organic extracts were dried over anhydrous magnesium sulfate, filtered and concentrated to an oil. The reaction mixture was purified by flash chromatography over silica gel (150 mL, eluent: 15% ethyl acetate in hexane) to obtain 1.22 g (52%) of the title compound as a white solid. TLC analysis (Rf 0.23, 20% ethyl acetate in hexane). 1H NMR (CDCl3, 300 MHz) 7.24 (m, 1H), 7.14 (m, 2H), 6.95 (m, 3H), 6.87 (m, 1H), 4.24 (br s, 1H), 3.56 (s, 2H), 2.82 (m, 2H), 2.59 (d, J=1.4 Hz, 2H), 2.50 (m, 2H), 1.74 (m, 2H), 1.50 (m, 2H), 0.91 (br s, 9H) MS (CI, CH4) m/z 396 (M+1,100), 398 (35), 424 (M+29,17), 378 (45), 360 (6). The free base was dissolved in diethyl ether containing a small amount of methylene chloride and acidified with ethereal HCl. The hydrochloride salt was filtered, washed with fresh ether and dried in vacuo (60° C., 13 pascal, 18 h) to yield a white solid, mp 294°-296° C.

Provenance & Evidence