Triphenylphosphine → 4-{(S)-4-Carboxy-2-[(5-cyclobutoxy-1-phenyl-1H-pyrazole-3-carbonyl)-amino]butyryl}-piperazine-1-carboxylic acid ethyl ester

Participants

Reaction Steps

To a solution of 50 mg of 4-{(S)-4-tert-Butoxycarbonyl-2-[(5-hydroxy-1-phenyl-1H-pyrazole-3-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester and 8 mg of Cyclobutanol in 2 ml of THF, 37 mg of polymerbound triphenyl phosphine (Fluka, 3 mmol triphenylphosphine/g resin) and 20 mg of Diethyl azodicarboxylate was added and stirred for 16 h. Then, the reaction mixture was filtered and the solvents were removed under reduced pressure. The residue was dissolved in 1 ml of DCM and 0.2 ml TFA. After 4 h 10 ml of toluene was added and the solvents were removed under reduced pressure. The residue was purified by preparative HPLC (C18 reverse phase column, elution with a water/MeCN gradient with 0.1% TFA). The fractions containing the product were evaporated and lyophilized to yield a white solid. Yield: 2 mg MS (ES+): m/e=528.

Provenance & Evidence