Sulfuric Acid → Ethyl (1R,2S)-1-amino-2-ethenylcyclopropanecarboxylate sulphate (2:1)

Temperature

40 °C

An ethyl acetate solution of the (1R,2S)-1-amino-1-ethoxycarbonyl-2-vinylcyclopropane obtained in Example 30 was cooled to 2° C., and then, using a dropping funnel, 69.34 g (1.372 mmol) of 97% sulfuric acid was added dropwise thereto over 50 minutes. Sulfuric acid remaining in the dropping funnel was transferred to the mixture using 87.64 g of ethyl acetate. Thereafter, the temperature of the mixture was increased to 40° C., and the mixture was then concentrated under reduced pressure to result in a liquid amount of 3.2 L. To the obtained concentrate, 1.2606 kg of toluene was added, and the mixture was then cooled to 0° C. over 2 hours. After the mixture had been kept cold at 0° C. for 2 hours, the generated crystal was collected by filtration. The obtained crystal was washed with 420.3 g of toluene, and it was then dried at room temperature for 2 hours under nitrogen current. Thereafter, it was dried under reduced pressure at 40° C. for 10 hours, so as to obtain 267.79 g of (1R,2S)-1-amino-1-ethoxycarbonyl-2-vinylcyclopropane hemisulfate salt in the form of a white crystal.

1. concentrationthe mixture was then concentrated under reduced pressure
2. customto result in a liquid amount of 3.2 L
3. concentrationTo the obtained concentrate
4. addition1.2606 kg of toluene was added
5. temperaturethe mixture was then cooled to 0° C. over 2 hours
6. waitAfter the mixture had been kept cold at 0° C. for 2 hours
7. filtrationthe generated crystal was collected by filtration
8. washThe obtained crystal was washed with 420.3 g of toluene, and it
9. customwas then dried at room temperature for 2 hours under nitrogen current
10. customThereafter, it was dried under reduced pressure at 40° C. for 10 hours

ORD record

ord-a4128a3b16c84af28835b203a2403633

Source dataset

uspto-grants-2015_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09061991B2