Formic Acid → 1,1-Dimethylethyl N-((1S,2S)-3-chloro-2-hydroxy-1-(phenylmethyl)propyl)carbamate

Participants

Reaction Steps

(3S)-3-tert-Butoxycarbonylamino-1-chloro-4-phenyl-2-butanone (1.49 g, 5.0 mmol), 90% formic acid (0.224 ml, 5.25 mmol), and triethylamine (0.730 ml, 5.25 mmol) were added to a solution of chloro(pentamethylcyclopentadienyl)rhodium (III) (1S,2S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine (3.4 mg, 0.005 mmol, s/c=1000) in dichloromethane (10.0 ml), followed by stirring at room temperature for 1 hour. Dichloromethane (20.0 ml) was added to the reaction mixture, and the stirring was continued for 1 hour at room temperature. After completion of the reaction, the reaction mixture was quantitatively analyzed by HPLC to confirm production of a desired compound, (2S, 3S)-3-tert-butoxycarbonylamino-1-chloro-2-hydroxy-4-phenylbutane (1.50 g; yield: 99.9%). The production ratio of the desired (2S,3S)-form to the isomeric (2R,3S)-form, (2S,3S):(2R,3S), was found to be 12.5:1. The resulting dichloromethane solution was evaporated, and the residue was crystallized from a mixed solvent of water, toluene and ethanol (1:1:3) to give a mixture at a (2S,3S) to (2R,3S) ratio of 99.6:0.4 in a yield of 80%.

Provenance & Evidence