Allyl bromide → Cyclopropanecarboxylic acid, 1-(2-propenyl)-, 1,1-dimethylethyl ester

関与物質

反応条件

反応手順

15.9 ml (1.15 equiv.) diisopropylamine were dissolved in 65 ml tetrahydrofuran and cooled to ca −10° C. 65 ml (1.08 equiv.) 1.6 M butyllithium solution in hexane were added over 25 min, maintaining the temperature between −10° C. and 0° C. After 50 nm in at ca. −5° C., the reaction mixture was cooled to −75° C. A solution of 15 g (96.7 mmol, 1 equiv., 92% w/w purity) cyclopropanecarboxylic acid tert-butyl ester in 20 ml tetrahydrofuran was added over 15 min keeping the temperature between −75° C. and −70° C. The reaction mixture was stirred 5 h at −75° C. (milky reaction mixture obtained after 2.5 h). A solution of 12.87 g (1.10 equiv.) allyl bromide was added over 20 min keeping the temperature between −75° C. and −60° C. The reaction mixture was stirred at −78° C. for 1 h, warmed to room temperature and stirred overnight. The reaction mixture was cooled to 0° C. 100 ml sat. aq. ammonium chloride solution were added followed by 30 ml water providing a clear biphasic mixture. The mixture was extracted 3 times with 50 ml tert-butyl methyl ether. The organic phases were combined, dried over sodium sulfate, filtered and concentrated under reduced pressure (40° C./20 mbar) to afford 16.44 g of crude product. The crude product was distilled (2 mbar; ca 40° C. distillation head temperature) to provide the title compound in ca 65% yield.

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