Phenylhydrazine → Ethyl 2-chloro-2-fluorocyclopropanecarboxylate

Participants

Reaction Conditions

Reaction Steps

Cyclohexane (76.6 g), 2,2′-isopropylidenebis[(4S)-4-tert-butyl-2-oxazoline] (500 mg, 1.7 mmol), and copper (II) trifluoromethanesulfonate (360 mg, 1.0 mmol) were added in an autoclave, and the mixture was cooled to a temperature below −30° C., and then 1-chloro-1-fluoroethylene (80 g, 1.0 mol) was charged under elevated pressure. Phenylhydrazine (0.11 g, 1.0 mmol) was added to this mixture under elevated pressure, and then temperature was raised to 30° C. Then, a mixed solution containing 97.6% of ethyl diazoacetate (11.69 g, 100 mmol) and cyclohexane (50 g) was charged under elevated pressure over five hours. Cyclohexane (20 ml) was further charged under elevated pressure and stirring was continued at the same temperature for 1 hour, and then the internal pressure was released to give a solution of ethyl 2-chloro-2-fluorocyclopropanecarboxylate in cyclohexane (166.7 g). The content of was 3.95% (yield based on ethyl diazoacetate: 39.5%), and the ratio of cis-isomer/trans-isomer was 65.0/35.0. The optical purity of the cis-isomer was 98% e.e. (1S,2R) or more, and the optical purity of the trans-isomer was 94% e.e. (1S,2S).

Provenance & Evidence