Cyclometalated Ir(III) complexes-catalyzed aerobic hydroxylation of arylboronic acids induced by visible-light

Scalable and Practical Approach of Phenol Formation from Hydroxylation of Arylboronic Acids under Metal-, Photocatalyst-, and Light-Free Conditions

Phenols are of particular importance owing to their widespread application in various fields, including life sciences and synthetic chemistry. However, the typical synthetic strategies of phenol either rely on metal- or photo-catalysts or involve stringent conditions such as high temperature, strong oxidants, and acidic or basic environments. Herein, we present a remarkably simple, ecofriendly, and photocatalyst-free synthesis of phenols. In contrast to conventional methods, which relies on expensive catalysts or hazardous reagents, the current diacetoxyiodobenzene-mediated hydroxylation of arylboronic acid protocol offers significant improvement in terms of costs, operational simplicity, toxicity, and sustainability. The reaction does not require high temperature or light activation and shows good functional group compatibility and conversion efficiency (55-96%). Moreover, these mild reaction conditions are also useful for gram-scale synthesis without compromising the reaction yield.

Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source

Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp³)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.