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

Participants

Reaction Conditions

Reaction Steps

Tetrahydrofuran (80 g) was poured into (1R,2S)-1-amino-2-vinylcyclopropanecarboxylic acid ethyl ester 4-chlorobenzoate (8.0 g, 25.7 mmol) obtained in Example 25. After stirring, a mixed liquid of 96% sulfuric acid (1.31 g, 12.8 mmol) and tetrahydrofuran (80 g) was added dropwise over 2.5 hours. The obtained mixture was stirred at room temperature for 1 hour, cooled to 1° C. over 2.5 hours and then filtered at the same temperature to obtain a solid. The obtained solid was washed with a mixed liquid of tetrahydrofuran (8 g) and toluene (4 g) and then dried under reduced pressure to obtain (1R,2S)-1-amino-2-vinylcyclopropanecarboxylic acid ethyl ester hemisulfate having an optical purity of more than 99% e.e. (3.98 g, 19.5 mmol). Yield: 76%.

Provenance & Evidence