332-25-2Relevant articles and documents
Electrochemical Trifluoromethoxylation of (Hetero)aromatics with a Trifluoromethyl Source and Oxygen
Ouyang, Yao,Qing, Feng-Ling,Xu, Xiu-Hua
supporting information, (2021/12/06)
Trifluoromethoxylated aromatics (ArOCF3) are valuable structural motifs in the area of drug discovery due to the enhancement of their desired physicochemical properties upon the introduction of the trifluoromethoxy group (CF3O). Although significant progress has been made recently in the introduction of CF3O group into aromatics, current methods either require the use of expensive trifluoromethoxylation reagents or require harsh reaction conditions. We present a conceptually new and operationally simple protocol for the direct C?H trifluoromethoxylation of (hetero)aromatics by the combination of the readily available trifluoromethylating reagent and oxygen under electrochemical reaction conditions. This reaction proceeds through the initial generation of CF3 radical followed by conversion to CF3O radical, addition to (hetero)aromatics and rearomatization. The utility of this electrochemical trifluoromethoxylation is illustrated by the direct incorporation of CF3O group into a variety of (hetero)aromatics as well as bio-relevant molecules.
Development and Molecular Understanding of a Pd-Catalyzed Cyanation of Aryl Boronic Acids Enabled by High-Throughput Experimentation and Data Analysis
De Jesus Silva, Jordan,Bartalucci, Niccolò,Jelier, Benson,Grosslight, Samantha,Gensch, Tobias,Schünemann, Claas,Müller, Bernd,Kamer, Paul C. J.,Copéret, Christophe,Sigman, Matthew S.,Togni, Antonio
, (2021/11/10)
A synthetic method for the palladium-catalyzed cyanation of aryl boronic acids using bench stable and non-toxic N-cyanosuccinimide has been developed. High-throughput experimentation facilitated the screen of 90 different ligands and the resultant statistical data analysis identified that ligand σ-donation, π-acidity and sterics are key drivers that govern yield. Categorization into three ligand groups – monophosphines, bisphosphines and miscellaneous – was performed before the analysis. For the monophosphines, the yield of the reaction increases for strong σ-donating, weak π-accepting ligands, with flexible pendant substituents. For the bisphosphines, the yield predominantly correlates with ligand lability. The applicability of the designed reaction to a wider substrate scope was investigated, showing good functional group tolerance in particular with boronic acids bearing electron-withdrawing substituents. This work outlines the development of a novel reaction, coupled with a fast and efficient workflow to gain understanding of the optimal ligand properties for the design of improved palladium cross-coupling catalysts.
Visible-Light-Promoted Metal-Free Synthesis of (Hetero)Aromatic Nitriles from C(sp3)?H Bonds**
Murugesan, Kathiravan,Donabauer, Karsten,K?nig, Burkhard
supporting information, p. 2439 - 2445 (2020/12/07)
The metal-free activation of C(sp3)?H bonds to value-added products is of paramount importance in organic synthesis. We report the use of the commercially available organic dye 2,4,6-triphenylpyrylium tetrafluoroborate (TPP) for the conversion of methylarenes to the corresponding aryl nitriles via a photocatalytic process. Applying this methodology, a variety of cyanobenzenes have been synthesized in good to excellent yield under metal- and cyanide-free conditions. We demonstrate the scope of the method with over 50 examples including late-stage functionalization of drug molecules (celecoxib) and complex structures such as l-menthol, amino acids, and cholesterol derivatives. Furthermore, the presented synthetic protocol is applicable for gram-scale reactions. In addition to methylarenes, selected examples for the cyanation of aldehydes, alcohols and oximes are demonstrated as well. Detailed mechanistic investigations have been carried out using time-resolved luminescence quenching studies, control experiments, and NMR spectroscopy as well as kinetic studies, all supporting the proposed catalytic cycle.
