Cyclohexylamine → (E)-2(R)-[1(R)-(tert-butoxycarbonyl)-4-phenyl-3-butenyl]-4-methylvaleric acid

Participants

Reaction Steps

A solution of 5.19 g of 4-tert-butyl hydrogen 2(R)-isobutylsuccinate in 50 ml of dry tetrahydrofuran was cooled to −78° C. while stirring under nitrogen. 25 ml of a 2M solution of lithium diisopropylamide in tetrahydrofuran was added dropwise and the mixture was stirred at −78° C. for 15 minutes. A solution of 5.55 g of cinnamyl bromide in 25 ml of dry tetrahydrofuran was then added dropwise and the mixture was left to come to room temperature gradually. After stirring overnight the tetrahydrofuran was evaporated and the residue was partitioned between ethyl acetate and 5% citric acid solution. The ethyl acetate layer was washed with two further portions of 5% citric acid solution, water and saturated sodium chloride solution and then dried over anhydrous magnesium sulphate. The solvent was evaporated to give an orange oil. This was dissolved in 100 ml of hexane to which 2.35 g of cyclohexylamine were added. The mixture was left to stand for 2 hours and the solid formed was collected by filtration. The solid was suspended in ethyl acetate and shaken with two portions of 2M sulphuric acid to give a clear solution. The ethyl acetate solution was washed twice with water and then with saturated sodium chloride solution and subsequently dried over anhydrous magnesium sulphate. After evaporation of the solvent there were obtained 6.41 g of (E)-2(R)-[1(R)-(tert-butoxycarbonyl)-4-phenyl-3-butenyl]-4-methylvaleric acid in the form of a pale cream coloured solid.

Provenance & Evidence