Reversible Formation of a Cationic Palladium(II) Hydride [HPd(PPh3)2]+ in the Oxidative Addition of Acetic or Formic Acid to Palladium(0) in DMF

Palladium-Catalyzed Intramolecular 5-exo-dig Hydroarylations of N-Arylpropiolamides: Thermodynamics-Controlled Stereoselective Synthesis of 3-Methyleneoxindoles

“…Two possible mechanisms were proposed as outlined in Scheme on the basis of the reported mechanism and the present results. − , Sequential C−H activation/complexation with alkyne affords intermediate B , followed by cis - and/or trans -addition to yield intermediates ( Z )- C and/or ( E )- C . Protonation of intermediates C takes place to give the desired products ( Z )- 2 and/or ( E )- 2 .…”

Palladium-Catalyzed Intramolecular 5-exo-dig Hydroarylations of N-Arylpropiolamides: Thermodynamics-Controlled Stereoselective Synthesis of 3-Methyleneoxindoles

“…Two possible mechanisms were proposed as outlined in Scheme on the basis of the reported mechanism and the present results. − , Sequential C−H activation/complexation with alkyne affords intermediate B , followed by cis - and/or trans -addition to yield intermediates ( Z )- C and/or ( E )- C . Protonation of intermediates C takes place to give the desired products ( Z )- 2 and/or ( E )- 2 .…”

Pd Catalyzed, Acid Accelerated, Rechargeable, Liquid Organic Hydrogen Carrier System Based on Methylpyridines/Methylpiperidines

“…On the basis of the control experiments, preliminary mechanistic studies, and the literature, 34,35 a plausible dehydrogenation mechanism (Scheme 3a) and pathway (Scheme 3b) of 2-picoline and 2,6-lutidine formation are proposed. The oxidative addition of carboxylic acid (from added acid or the carboxyl group on the activated carbon surface) to Pd(0) generates an active Pd(II) species RCO 2 − Pd−H.…”

“…The oxidative addition of carboxylic acid (from added acid or the carboxyl group on the activated carbon surface) to Pd(0) generates an active Pd(II) species RCO 2 − Pd−H. 35 Coordination of the N-heterocycle to Pd(II) on the nanoparticle surface results in an increase of the acidity of the N−H group, which could be deprotonated by the counter carboxylate anions of Pd(II) to generate an amido-palladium species and carboxylic acid. This is followed by β-hydride elimination to generate an imine and a palladium dihydride species.…”

Enantiodivergent Synthesis of Tertiary α-Aryl 1-Indanones: Evidence Toward Disparate Mechanisms in the Palladium-Catalyzed Decarboxylative Asymmetric Protonation

“…Upon fragmentation of intermediate III (steps C, D) the catalyst is regenerated. Expelled β-keto acid II undergoes a second oxidative addition by the active palladium species (step E) and decarboxylation (step F) to form hydridopalladum species VI . In contrast to the homogeneous protonation, the protonated product is formed via intramolecular reductive elimination (step G).…”

Palladium-Catalyzed Intramolecular 5-exo-dig Hydroarylations of N-Arylpropiolamides: Thermodynamics-Controlled Stereoselective Synthesis of 3-Methyleneoxindoles

“…Two possible mechanisms were proposed as outlined in Scheme on the basis of the reported mechanism and the present results. − , Sequential C−H activation/complexation with alkyne affords intermediate B , followed by cis - and/or trans -addition to yield intermediates ( Z )- C and/or ( E )- C . Protonation of intermediates C takes place to give the desired products ( Z )- 2 and/or ( E )- 2 .…”

Pd Catalyzed, Acid Accelerated, Rechargeable, Liquid Organic Hydrogen Carrier System Based on Methylpyridines/Methylpiperidines

“…On the basis of the control experiments, preliminary mechanistic studies, and the literature, 34,35 a plausible dehydrogenation mechanism (Scheme 3a) and pathway (Scheme 3b) of 2-picoline and 2,6-lutidine formation are proposed. The oxidative addition of carboxylic acid (from added acid or the carboxyl group on the activated carbon surface) to Pd(0) generates an active Pd(II) species RCO 2 − Pd−H.…”

“…The oxidative addition of carboxylic acid (from added acid or the carboxyl group on the activated carbon surface) to Pd(0) generates an active Pd(II) species RCO 2 − Pd−H. 35 Coordination of the N-heterocycle to Pd(II) on the nanoparticle surface results in an increase of the acidity of the N−H group, which could be deprotonated by the counter carboxylate anions of Pd(II) to generate an amido-palladium species and carboxylic acid. This is followed by β-hydride elimination to generate an imine and a palladium dihydride species.…”

Enantiodivergent Synthesis of Tertiary α-Aryl 1-Indanones: Evidence Toward Disparate Mechanisms in the Palladium-Catalyzed Decarboxylative Asymmetric Protonation

“…Upon fragmentation of intermediate III (steps C, D) the catalyst is regenerated. Expelled β-keto acid II undergoes a second oxidative addition by the active palladium species (step E) and decarboxylation (step F) to form hydridopalladum species VI . In contrast to the homogeneous protonation, the protonated product is formed via intramolecular reductive elimination (step G).…”

Palladium-Catalyzed Intramolecular 5-exo-dig Hydroarylations of N-Arylpropiolamides: Thermodynamics-Controlled Stereoselective Synthesis of 3-Methyleneoxindoles

“…Two possible mechanisms were proposed as outlined in Scheme on the basis of the reported mechanism and the present results. − , Sequential C−H activation/complexation with alkyne affords intermediate B , followed by cis - and/or trans -addition to yield intermediates ( Z )- C and/or ( E )- C . Protonation of intermediates C takes place to give the desired products ( Z )- 2 and/or ( E )- 2 .…”

Pd Catalyzed, Acid Accelerated, Rechargeable, Liquid Organic Hydrogen Carrier System Based on Methylpyridines/Methylpiperidines

“…On the basis of the control experiments, preliminary mechanistic studies, and the literature, 34,35 a plausible dehydrogenation mechanism (Scheme 3a) and pathway (Scheme 3b) of 2-picoline and 2,6-lutidine formation are proposed. The oxidative addition of carboxylic acid (from added acid or the carboxyl group on the activated carbon surface) to Pd(0) generates an active Pd(II) species RCO 2 − Pd−H.…”

“…The oxidative addition of carboxylic acid (from added acid or the carboxyl group on the activated carbon surface) to Pd(0) generates an active Pd(II) species RCO 2 − Pd−H. 35 Coordination of the N-heterocycle to Pd(II) on the nanoparticle surface results in an increase of the acidity of the N−H group, which could be deprotonated by the counter carboxylate anions of Pd(II) to generate an amido-palladium species and carboxylic acid. This is followed by β-hydride elimination to generate an imine and a palladium dihydride species.…”

Enantiodivergent Synthesis of Tertiary α-Aryl 1-Indanones: Evidence Toward Disparate Mechanisms in the Palladium-Catalyzed Decarboxylative Asymmetric Protonation

“…Upon fragmentation of intermediate III (steps C, D) the catalyst is regenerated. Expelled β-keto acid II undergoes a second oxidative addition by the active palladium species (step E) and decarboxylation (step F) to form hydridopalladum species VI . In contrast to the homogeneous protonation, the protonated product is formed via intramolecular reductive elimination (step G).…”