Pyridine → (1R,2S,5R)-2-isopropyl-5-methylcyclohexyl (E)-3-(3,4-difluorophenyl)-2-propenoate

Participants

Reaction Conditions

Reaction Steps

A solution of L-menthol (7.1 kg) in toluene (8.5 kg) was added over a 20 minute period to the solution of (E)-3-(3,4-difluorophenyl)-2-propenoyl chloride (prepared as in Example 2) and pyridine (0.18 kg, 2.28 mol) stirring at 65° C. The reaction mixture was stirred at 65° C. for a further 4 hours and 40 minutes after the addition was complete, then cooled to 25° C. and stirred for a 14 hours. The solution was diluted with toluene (16 kg), washed with 5% aqueous sodium chloride (6.4 kg), then 6% sodium hydrogen carbonate (6.47 kg), then water (6.1 kg). The solution was dried azeotropically by distillation of the solvent (20 L) under reduced pressure. Dimethyl sulfoxide (33.9 kg) was added and the remaining toluene was distilled off under reduced pressure, affording 47.3 kg of a solution of (1R,2S,5R)-2-isopropyl-5-methylcyclohexyl (E)-3-(3,4-difluorophenyl)-2-propenoate (approx. 13.3 kg) in dimethyl sulfoxide.

Provenance & Evidence