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Published on: November 30, 2022
Ligand-Dependent Site-Selective Suzuki Cross-Coupling of 4-Bromopyrazol-5-yl Triflates
Ryo Sakakibara1, Kennosuke Itoh, Hideaki Fujii
1Sohyaku, Innovative Research Division , Mitsubishi Tanabe Pharma Corporation , 2-2-50, Kawagishi , Toda , Saitama 335-8505 , Japan.
Abstract:
Ligand-dependent Suzuki cross-coupling of 4-bromopyrazol-5-yl triflates has been developed. This approach enabled selective introduction of an aryl substituent at the C4 or C5 position in pyrazoles. This protocol is the first example in which the cross-coupling proceeded predominantly at the C4 position in pyrazoles, which is generally recognized as the least reactive position. The selection of phosphine ligands switched the order of arylation. This method should be highly useful for preparing diverse poly-substituted pyrazole derivatives.
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