Pd(0)/TPPMS-Catalyzed Tsuji-Trost Type Cross-Coupling of Allylic Alcohols with Organoboron Compounds in Water

We demonstrated that the combination of a Pd(0) catalyst and a water-soluble TPPMS ligand has high activity for the direct arylation of readily available allylic alcohols in the Tsuji-Trost type cross-coupling. Various organoboron reagents can be applied, enabling rapid access to the corresponding arylated products with a wide range of functional group tolerance. Kinetic studies revealed a first-order rate dependence for the allylic alcohol, boronic acid, CsF and Pd(0)/TPPMS concentrations. A Hammett study found a slightly positive rho value of 0.79, suggesting that a partial negative charge is generated on the aromatic ring of the aryl boronate in the rate-determining transmetalation step. Based on several control experiments, we concluded that the transmetalation employing CsF would proceed via the oxo-palladium mechanism. We demonstrated that the combination of a Pd(0) catalyst and a water-soluble TPPMS ligand has high activity for the direct arylation of readily available allylic alcohols in the Tsuji-Trost type cross-coupling. This synthetic protocol features the direct arylation of readily available allylic alcohols instead of allylic halides, allowing an atom- and step-economic transformation in water. image