Toluene → (R)-ethyl-3-(4-chlorophenyl)-4-(2-propenyl)hexahydro-1-pyrazinecarboxylate

Participants

Reaction Conditions

Reaction Steps

In distilled water (5 mL), (R)-2-(4-Chlorophenyl)-4-(phenylmethyl)-1-(2-propenyl)hexahydropyrazine dihydrochloride (400 mg, 1.0 mmol) produced in Example 18 was dissolved. To the solution, toluene (5 mL) and 30 wt % aqueous solution of sodium hydroxide (401 mg, 3.0 equivalents) were added. After the organic layer and aqueous layer were separated, the organic layer was washed twice with distilled water (5 mL) and then concentrated. To the concentrate, hexane (5 mL) and ethyl chlorocarbonate (163 mg, 1.5 equivalents) were added. The mixture was stirred at 25° C. for 24 hours. Further, ethyl chlorocarbonate (328 mg, 3.0 equivalents) was added, and the mixture was stirred at 40° C. for 24 hours. After the mixture was cooled to 5° C., the precipitated crystals were collected by filtration under reduced pressure, washed with hexane (2 mL), and dried under vacuum, to obtain 22.5 mg of the title compound as while crystals (yield: 7%, chemical purity: 92.5 area %). Further, the filtrate was concentrated. To the concentrate, toluene (5 mL) was added and the toluene was distilled away. The operation was repeated 3 times. The obtained concentrate was dried under vacuum, to obtain 212 mg of the title compound as while turbid oil (yield: 69%, chemical purity: 95.9 area %). The retention time in the chemical purity analysis method was 22.7 min.

Provenance & Evidence