title: Diarylmethanes through an Unprecedented Palladium-Catalyzed C-C Cross-Coupling of 1-(Aryl)methoxy-1H-Benzotriazoles with Arylboronic Acids.
abstract: 1-(Aryl)methoxy-1H-benzotriazoles (ArCH2OBt) are bench-stable reagents that are prepared readily from 1H-benzotriazol-1-yl-4-methylbenzenesulfonate (BtOTs) and benzylic alcohols. These compounds, which contain a N-O-C bond, undergo cross-coupling with arylboronic acids by C-O bond scission with catalysts that comprise Pd(OAc)2and biarylphosphine ligands. Such reactivity of ArCH2OBt derivatives, leading to diarylmethanes, has not been described previously and constitutes a new activation of benzylic alcohols. With regard to the various ligands-metal complexes that support catalytic activity, it appears that those with smaller "percent buried volumes" (%Vbur) provide better outcomes. This factor has been evaluated in the initial optimization studies and in further reactions with difficult coupling partners. Ligand electronics of the biaryl moiety seem to play a lesser role in this type of reaction. The bis-coordinating bis[(2-diphenylphosphino)phenyl]ether appears to be suitable to improve the yields of low-yielding reactions.
authors.affiliation: Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031.
authors.forename: Manish K
authors.initials: MK
authors.lastname: Singh
authors.affiliation: Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031.
authors.forename: Mahesh K
authors.initials: MK
authors.lastname: Lakshman
keywords: Csp3–Csp2 cross-coupling; Pd catalysis; benzotriazole; boronic acid; phosphine ligands