2,5-Dimethylpiperazine, trans- → (+/-)-trans-1-(4-Bromo-alpha-(3-(tert-butyldimethylsilyloxy)phenyl)benzyl)-2,5-dimethylpiperazine

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Reaction Steps

The crude benzhydryl chloride (approx. 135 mmol) was combined with 46.3 g (405 mmol) of trans-2,5-dimethylpiperazine (purified by recrystallization from toluene to mp=115°-119° C.) and 30 mL of toluene and heated at reflux overnight under nitrogen. The toluene was removed under vacuum, and the residue was redissolved in 2000 mL of diethyl ether and washed with 500 mL of 1.0M sodium hydroxide and 1000 mL of water. The ether solution was dried over sodium sulfate and the solvent removed to give a dark oil. The product was purified by chromatography on silica gel with 1-10% ethanol in dichloromethane to give 41.0 g (62%) of (±)-trans-1-(4-bromo-α-(3-(tert-butyldimethylsilyloxy)phenyl)benzyl)-2,5-dimethylpiperazine as a 1:1 mixture of diastereomers. NMR (300 MHz, CDCl3); δ 0.15 (s, 6H); 0.9 (m,12H); 1.2 (d,J=6 Hz,3H); 1.4-1.6 (m,2H); 2.2-3.0 (m,5H); 5.2 and 5.3 (s,1H); 6.6-7.5 (m,8H).

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