反应详情

A suspension of 3.0 g (12 mmol) of (R)-α-(pivaloylmethyl)hydrocinnamic acid (see EPA 0,184,550) and 2.66 g (11 mmol) of L-histidine methyl ester dihydrochloride in 340 ml of dimethylformamide was treated at room temperature under a nitrogen atmosphere with 3.45 g (34 mmol) of triethylamine and 4.58 g (12 mmol) of HBTU. The reaction mixture was stirred at room temperature for 5 hours and subsequently evaporated in a high vacuum. The residue was dissolved in 500 ml of ethyl acetate and washed in succession with 100 ml of water, three times with 100 ml of saturated sodium bicarbonate solution each time and with 100 ml of saturated sodium chloride solution. The organic phase was dried over sodium sulfate, evaporated under reduced pressure and the yellowish crude product obtained was chromatographed on silica gel with a 95:5 mixture of methylene chloride and methanol which contained 0.1% ammonia. In this manner there were obtained 3.6 g of N-[(R)-α-(3,3-dimethyl-2-oxobutyl)hydrocinnamoyl]-L-histidine methyl ester as a colourless foam, MS: 399(M)+.

1. customsubsequently evaporated in a high vacuum
2. dissolutionThe residue was dissolved in 500 ml of ethyl acetate
3. washwashed in succession with 100 ml of water, three times with 100 ml of saturated sodium bicarbonate solution each time
4. dry with materialThe organic phase was dried over sodium sulfate
5. customevaporated under reduced pressure
6. customthe yellowish crude product obtained
7. customwas chromatographed on silica gel with a 95:5 mixture of methylene chloride and methanol which