phenyl piperazine-1-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 100 mg (S)-2-({5-[2-((S)-2-cyclobutylcarbamoyl-pyrrolidin-1-yl)-2-oxo-ethoxy]-1-phenyl-1H-pyrazole-3-carbonyl}-amino)-pentanedioic acid 5-tert-butyl ester in 5 ml DMF were added 55 μl DIPEA, 64 mg HATU and 54 mg piperazine-1-carboxylic acid phenyl ester hydrotrifluoroacetate. After stirring for 36 h the solution was concentrated, the residue dissolved in 1.5 ml dichloromethane and treated with 190 μl TFA. After stirring for 4 h the solvents were removed under reduced pressure and the residue purified by preparative HPLC (C18 reverse phase column, elution with a water/MeCN gradient with 0.1% TFA). The fractions containing the product were lyophilized to yield the pure product. Yield: 40 mg MS (ES+): m/e=730. was concentrated the residue dissolved in 1.5 ml dichloromethane treated with 190 μl TFA After stirring for 4 h the solvents were removed under reduced pressure the residue purified by preparative HPLC ( C18 reverse phase column, elution with a water/MeCN gradient with 0.1% TFA) The fractions containing the product to yield the pure product

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Crude piperazine-1,4-dicarboxylic acid tert-butyl ester phenyl ester was dissolved in 10 ml dichloromethane and treated with 4 ml TFA. After stirring for 12 h the solution was concentrated and the residue codistilled twice with toluene. Yield: 3.0 g. was concentrated