1,2-Dichloroethane → (S)--N--[(1S,2R,3RS)-1-(cyclohexylmethyl)-4-ethyl-2,3-dihydroxyhexyl]-alpha-[(R)-alpha-(3,3-dimethyl-2-oxobutyl)hydrocinnamamido]imidazole-4-propionamide

Participants

Reaction Steps

A mixture of 880 mg (2.23 mmol) of (S)-α-amino-N-[(1S,2R,3RS)-1-(cyclohexylmethyl)-4-ethyl-2,3-dihydroxyhexyl]imidazole-4-propionamide, 608 mg (2.45 mmol) of (R)-α-(pivaloylmethyl)hydrocinnamic acid (see EpA 0 184 550), 0.35 ml (2.76 mmol) of 4-ethylmorpholine, 662 mg (4.9 mmol) of HBT and 529 mg (2.76 mmol) of EDC in 20 ml of dimethylformamide is stirred at room temperature overnight. Thereafter, the reaction mixture is evaporated to dryness in a high vacuum, the residue is poured into a mixture of ice and 2N sodium bicarbonate solution and extracted three times with ethyl acetate. The extracts are washed in succession with saturated ammonium chloride solution, 2N sodium bicarbonate solution and saturated sodium chloride solution and combined. After drying the organic solution over magnesium sulphate the solvent is evaporated under reduced pressure and the residue (1.01 g), for purification, is chromatographed on 70 g of silica gel using a 20:1:0.1 mixture of methylene chloride, methanol and ammonia as the eluting agent. Crystallization of the thus-obtained crude product from methylene chloride/methanol/ether yields 900 mg of (S)-N-[(1S,2R,3RS)-1-(cyclohexylmethyl)-4-ethyl-2,3-dihydroxyhexyl]-α-[(R)-α-(3,3-dimethyl-2-oxobutyl)hydrocinnamamido]imidazole-4-propionamide, melting point 160° , MS: 624 (M)+.

Provenance & Evidence