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)‐ bi...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.展开更多
Carbocations such as tropylium and trityl cation, can be stable enough to be isolated and used without inert conditions. They can act as Lewis acids to lower the LUMO of electrophile, thus promoting reactions with nuc...Carbocations such as tropylium and trityl cation, can be stable enough to be isolated and used without inert conditions. They can act as Lewis acids to lower the LUMO of electrophile, thus promoting reactions with nucleophiles. Additionally, the interaction between carbocations and alcohols can form Bronsted acids with enhanced acidity. Furthermore, electrophoto activation of TAC^(+)(trisaminocyclopropenium ion)delivers the excited radical dication TAC·^(2+*), which is a strong oxidant and capable of oxidizing a range of challenging substrates. Moreover,^(n)Pr-DMQA^(+) is disclosed as a versatile photoredox catalyst as its excited state can be quenched through both oxidation and reduction. This review summarizes recent advance in carbocation-catalyzed reactions. These developed methods provide an environmentally friendly pathway for the synthesis of valuable compounds and will inspire chemists to discover more interesting transformations promoted by carbocations.展开更多
文摘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.
基金Financial support from National Natural Science Foundation of China (No. 21871053)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (No. 2019R01005)the Open Research Fund of School of Chemistry and Chemical Engineering, Henan Normal University (No. 2020ZD04) is gratefully acknowledged。
文摘Carbocations such as tropylium and trityl cation, can be stable enough to be isolated and used without inert conditions. They can act as Lewis acids to lower the LUMO of electrophile, thus promoting reactions with nucleophiles. Additionally, the interaction between carbocations and alcohols can form Bronsted acids with enhanced acidity. Furthermore, electrophoto activation of TAC^(+)(trisaminocyclopropenium ion)delivers the excited radical dication TAC·^(2+*), which is a strong oxidant and capable of oxidizing a range of challenging substrates. Moreover,^(n)Pr-DMQA^(+) is disclosed as a versatile photoredox catalyst as its excited state can be quenched through both oxidation and reduction. This review summarizes recent advance in carbocation-catalyzed reactions. These developed methods provide an environmentally friendly pathway for the synthesis of valuable compounds and will inspire chemists to discover more interesting transformations promoted by carbocations.
