Ethylmorpholine → N-[N-(tert-butoxycarbonyl)-3-methyl-L-valyl]-3-cyclopentyl-L-alanine benzyl ester

Participants

Reaction Steps

1.54 g (4.44 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester and 2.53 g (13.32 mmol) of 4-toluenesulphonic acid hydrate were dissolved in 20 ml of acetonitrile and the solution was left to standat room temperature for 18 hours. The white precipitate formed was filteredoff and added to a mixture of 867 mg (3.75 mmol) of N-(tert-butoxycarbonyl)-3-methyl-L-valine, 557 mg (3.64 mmol) of 1-hydroxybenzotriazole, 793 mg (4.14 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 475 mg (4.13 mmol) of N-ethylmorpholine in 25 ml of dichloromethane and stirred at room temperature for 18 hours. The solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution and then driedover anhydrous magnesium sulphate. Evaporation and chromatography on silicagel using ethyl acetate/petrol (1:3) for the elution gave 1.06 g of N-[N-(tert-butoxycarbonyl)-3-methyl-L-valyl]-3-cyclopentyl-L-alanine benzyl ester as an off-white foam; MS: m/e 461 [M+H].

Provenance & Evidence