Acetic Acid → N-(4-methoxybenzyl)pyrimidin-4-amine

Participants

Reaction Steps

p-Anisaldehyde (320 g, 2.35 mol, 1.0 equiv; Aldrich, St. Louis, Mo.) and 4-aminopyrimidine (246 g, 2.58 mol, 1.1 equiv; AK Scientific, Inc., Union City, Calif.) were dissolved in anhydrous DCM (8.0 L). To this solution under N2 atmosphere at room temperature was added a solution of Ti (Oi-Pr)3Cl (1348 g, 5.17 mol, 2.2 equiv; Aldrich) in anhydrous DCM (1 L) in one portion and the reaction mixture was stirred at room temperature for 30 minutes. The reaction mixture was then cooled to 10° C. and NaBH(OAc)3 (1495 g, 7.05 mol, 3.0 equiv; Aldrich) was added in portions over 30 min followed by the addition of acetic acid (10 mL). (Note: A mild exotherm of 10-19° C. was observed). Upon completion of the addition, the reaction mixture was allowed to warm up to room temperature and stirred overnight. The reaction was monitored using LC/MS. Product formation was observed along with many other peaks. Upon completion the reaction mixture was quenched slowly and carefully pouring over a well-stirred saturated aqueous NaHCO3 (30 L). The crude product was then extracted with dichloromethane (3×12 L) and the organic extracts were combined, washed with brine (5 L), dried over Na2SO4, and concentrated under reduced pressure. The crude residue was initially triturated with hexanes to obtain a solid. The crude solid was further triturated with MTBE to remove most of the impurities. The crude product was purified using column chromatography eluting with MeOH/ethyl acetate (2:98 to 5:95) to afford N-(4-methoxybenzyl)pyrimidin-4-amine (INTERMEDIATE OO) as a white solid with >99% purity (129 g, 26% yield). 1H NMR (400 MHz, DMSO) δ ppm 8.40 (s, 1H), 8.02 (d, J=6.1 Hz, 1H), 7.82 (t, J=6.0 Hz, 1H), 7.24 (d, J=8.0 Hz, 2H), 6.98-6.77 (m, 2H), 6.48 (s, 1H), 4.43 (s, 2H), 3.72 (s, 3H). m/z (ESI) 216.0 (M+H)+

Provenance & Evidence