874299-63-5

Upstream product

• 205259-72-9 rhodium(III) tetrakis(4-tolyl)porphyrin chloride 
• 7732-18-5 water 
• 104-87-0 4-methyl-benzaldehyde 
• 103533-61-5 (5,10,15,20-tetrakis-4-tolylporphyrinato)(methyl)rhodium(III) 
• 459-57-4 4-fluorobenzaldehyde 

Relevant academic research and scientific papers

Base-promoted selective activation of benzylic carbon-hydrogen bonds of toluenes with rhodium(III) porphyrin chloride: Synthetic scopes and mechanism

Toluenes underwent base-promoted selective benzylic carbon-hydrogen bond activation (CHA) with rhodium porphyrin chlorides (Rh(por)Cl). In the absence of nucleophilic base, both aryl and benzylic rhodium porphyrins were formed. In the presence of nucleophilic base, the selectivity, rates and functional group compatibilities of benzylic activation reactions were enhanced. K 2CO3 was found to be the optimal base to achieve the best yields. Ortho-, meta- and para-substituted toluenes in the presence of K 2CO3 yielded the corresponding rhodium porphyrin benzyls in high yields both in solvent-free conditions and in benzene solvent. Mechanistically, in the absence of nucleophilic base, a cationic rhodium(III) porphyrin species together with some rhodium(II) porphyrin are the most likely intermediates to account both the aryl and benzylic CHA. In the presence of a base, Rh(por)OH is generated by ligand substitution with Rh(por)Cl and rapidly undergoes reduction to give rhodium(II) porphyin dimer and H2O 2. The key rhodium porphyrin intermediates for benzylic CHA were found to be rhodium(II) porphyrin dimer and hydrides as observed by 1H NMR spectroscopy, which underwent parallel benzylic CHA reactions with the rhodium(II) porphyrin dimer being the more reactive intermediate.

Syntheses of acyl rhodium porphyrins by aldehydic carbon-hydrogen bond activation with Rh(III) porphyrin chloride and methyl

Rhodium(III) porphyrin chloride reacted with aryl aldehydes in solvent-free conditions to give acyl rhodium porphyrins. Selective aldehydic without any aromatic carbon-hydrogen bond activation (CHA) was observed. At lower temperature, reduction and side products were found. Alkanals reacted poorly. On the other hand, Rh(III) porphyrin methyl reacted more cleanly with both aryl and alkyl aldehydes. These reactions provided a facile, convenient synthesis of acyl rhodium porphyrins. These activations are unique CHA by high-valent Rh(III) species. Preliminary mechanistic experiments suggested that the rhodium(III) porphyrin chloride initially formed a cationic rhodium(III) porphyrin via chloride dissociation and then underwent oxidative addition or heterolysis to yield the product. On the other hand, rhodium(III) porphyrin methyl underwent either oxidative addition or σ bond metathesis.