In situ generation of trityl carbocation (Ph3C+) as a homogeneous organocatalyst for the efficient synthesis of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s

Trityl chloride (Ph3CCl) efficiently catalyzes the condensation of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and aromatic aldehydes under mild and solvent-free conditions, affording 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s in high to excellent yields and in short reaction time. The presence of the requisite organocatalytic trityl carbocation (Ph3C+) species was confirmed by analysis of infrared, 1H NMR, and ultra violet spectral data. A plausible mechanism was proposed for the reaction based on the observations and literature precedent.

Graphical AbstractEfficient synthesis of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s from 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and arylaldehydes using Ph3CCl under solvent-free conditions is described. A plausible reaction mechanism for the process based on the experimental data and that from similar literature studies is proposed.Figure optionsDownload full-size imageDownload as PowerPoint slide