Butyryl chloride → HCID 9831299, compound

Participants

Reaction Steps

50 μ(0.495 mmol) of butyric acid chloride and 2 mg (0.017 mmol) of DMAP are added to an ice-cooled mixture of 200 mg (0.33 mmol) of 1-[2(S)-hydroxy-3(S)-(N-(methoxy-carbonyl)-(L)-valyl)amino-4-phenyl-butyl]-1-[cyclohexylmethyl]-2-[N-methoxycarbonyl-(L)-valyl]-hydrazine (Example 73a) in 2.6 ml of dioxane and 0.4 ml of pyridine. After 18 h at RT, according to HPLC there is still 1-[2(S)-hydroxy-3(S)-(N-(methoxycarbonyl)-(L)-valyl)amino-4-phenyl-butyl]-1-[cyclohexylmethyl]-2-[N-methoxycarbonyl-(L)-valyl]-hydrazine present in the reaction mixture, and therefore a further 0.75 equivalents of butyric acid chloride and a few granules of DMAP are added. After a further 18 h, a 3rd portion of 1.5 equivalents of butyric acid chloride is added and the mixture is further stirred for one night at RT (→HPLC: fully reacted). The reaction mixture is diluted with ethyl acetate and washed with 2 portions of saturated NaHCO3 solution, water and brine, the aqueous phases are extracted twice with ethyl acetate, and the organic phases are dried with Na2SO4 and concentrated by evaporation. Digestion of the oily residue from hexane in an ultrasound bath yields the pure title compound: TLC Rf (O)=0.67; tRet (V)=17.2 min; FAB-MS (M+H)+ =676.

Provenance & Evidence