Lithium iodide → 1-(9,10-Dihydro-9,10-methanoanthracen-9-ylmethyl)-4-(4-methoxybenzyl)piperidin-4-ol

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Reaction Steps

Magnesium turnings (0.32 g, 1.32 mmol, 1.3 eq) were stirred in the absence of solvent for 15 min under nitrogen. Diethyl ether (20 mL) and catalytic lithium iodide were added, and the suspension was stirred vigorously for an additional 15 min at which time 4-methoxybenzyl chloride (1.08 mL, 7.0 mmol, 8 eq) was syringed into the reaction flask in portions. The reaction was refluxed for 3 h to assure Grignard formation and recooled to room temperature. 1-(9,10-Dihydro-9,10-methanoanthracen-9-ylmethyl)-4-piperidinone (described in example 5d) (0.30 g, 1.00 mmol) was added dropwise as a tetrahydrofuran solution (25 mL). After stirring for 18 h, the reaction was quenched with water (10 mL). The aqueous phase was extracted with ethyl acetate (200 mL). The organic extract was washed with water (2×100 mL), dried with anhydrous sodium sulfate, filtered, and reduced to an oil. The reaction mixture was purified by flash chromatography over silica gel (25 mL, eluent: 20% ethyl acetate in hexane) to yield 0.29 g (69%) of the title compound as a white solid. 1H NMR (CDCl3, 300 MHz) 7.23 (m, 2H), 7.13 (m 4H), 6.88 (m, 6H), 4.25 (s, 1H), 3.78 (s, 3H), 3.41 (s, 2H), 2.76 (m, 2H), 2.66 (s, 2H), 2.57 (d, J=1.2 Hz, 2H), 2.52 (m, 2H), 1.67 (m, 2H), 1.47 (m, 2H), 1.57 (s, 1H) MS (CI, CH4) m/z 426 (M+1,100), 454 (M+29,13), 408 (20). The free base was dissolved in methanol and methylene chloride, acidified with ethereal HCl and the salt precipitated with ether dilution. The hydrochloride salt was filtered, rinsed with fresh ether, and dried in vacuo (50° C. 10 pascal 18 h) to yield a white solid, mp 267°-268° C. (dec).

Provenance & Evidence