title: Palladium-Catalyzed Chelation-Assisted Regioselective Oxidative Dehydrogenative Homocoupling/Ortho-Hydroxylation in N-Phenylpyrazoles.
abstract: A palladium-catalyzed pyrazole-directed regioselective oxidative C(sp2)-H functionalization of the N-phenyl ring in N-phenylpyrazoles to afford either a biaryl bis-pyrazole (via dehydrogenative homocoupling) or N-(o-hydroxyphenyl)pyrazole (via C-H oxygenation) or their mixture is described. The substitutions on the N-phenyl ring and the pyrazole ring and the dilution of the reaction medium with respect to the TFA/TFAA mixture (substrate concentration) have a remarkable influence on the outcome of the reaction. It was discovered that if the reactions were performed under highly dilute conditions (ca. 10 times) then N-(o-hydroxyphenyl)pyrazoles were the major or the sole products.
authors.forename: Harikrishna
authors.initials: H
authors.lastname: Batchu
authors.forename: Soumya
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: Ruchir
authors.initials: R
authors.lastname: Kant
authors.affiliation: §Academy of Scientific and Innovative Research, New Delhi, 110025, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Batra
mesh_terms: D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry*; D006900:Hydroxylation; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; C000604318:N-(o-hydroxyphenyl)pyrazole; D011720:Pyrazoles; D010165:Palladium