(-)-Pseudoephedrine → Cyclohexanecarboxylate

Participants

Reaction Steps

(1R,2R)-2-(methylamino)-1-phenylpropan-1-ol (0.25 g, 1.50 mmol) was added to a solution of racemic trans-4-[1-(5-bromo-1,3-thiazol-2-yl)-1-hydroxyethyl]cyclohexanecarboxylic acid (500 mg, 1.50 mmol) and the resulting solution was stirred at room temperature overnight, at which point crystallization occurred. The resulting solid was collected by filtration and washed with 1:1 EtOAc:hexane. The resulting mother liquor was concentrated in vacuo and then isopropanol (3.5 mL) and (1S,2S)-2-(methylamino)-1-phenylpropan-1-ol were added. The reaction was stirred overnight, at which point crystallization occurred. Then EtOAc (3 mL) was added and after 20 minutes, the solid was collected via filtration and the filter cake was washed with EtOAc and then dried under a nitrogen bag to afford (1S,2S)-1-hydroxy-N-methyl-1-phenylpropan-2-aminium trans-4-[(1R or 1S)-1-(5-bromo-1,3-thiazol-2-yl)-1-hydroxyethyl]cyclohexanecarboxylate as a white solid. MS ESI calc'd. for C12H17BrNO3S [M+H]+ 334, 336. found 334, 336. 1H NMR (500 MHz, DMSO-d6) δ 7.73 (s, 1H), 7.30-7.27 (m, 4H), 7.25-7.19 (m, 1H), 5.95 (s, 1H), 4.20 (d, J=7.7, 1H), 2.60-2.52 (m, 1H), 2.29 (s, 3H), 2.03-1.92 (m, 1H), 1.92-1.86 (m, 1H), 1.86-1.78 (m, 2H), 1.63-1.52 (m, 1H), 1.48-1.37 (m, 4H), 1.27-1.08 (m, 4H), 1.06-0.89 (m, 1H), 0.68 (d, J=6.4, 3H).

Provenance & Evidence