1,3-Bis(diphenylphosphino)propane → 6-(4-tert-butyl-phenyl)-5H-pyrazolo[1,5-a]pyrazin-4-one

Participants

Reaction Conditions

Reaction Steps

140 mg (0.473 mmol) 6-(4-tert-butyl-phenyl)-4-oxo-4,5-dihydro-pyrazolo[1,5-a]pyrazine-2-carbaldehyde are dissolved in 1 ml diethyleneglycoldimethylether. 12 mg (0.028 mmol) 3-diphenylphosphanylpropyl(diphenyl)phosphane and 3.7 mg (0.014 mmol) rhodium(III)-chloride trihydrate are added. The reaction mixture is stirred for 42 hours at 160° C. The mixture is cooled to room temperature and partitioned between dichloromethane and water. The organic phase is dried over sodium sulfate and evaporated. The residue is chromatographed on a silica gel column with cyclohexane/ethyl acetate as eluent to give 6-(4-tert-butyl-phenyl)-5H-pyrazolo[1,5-a]pyrazin-4-one (“A15”) as colourless crystals; HPLC/MS: 1.88 (C), [M+H] 268.

Provenance & Evidence