Mechanistic significance of the si-o-pd bond in the palladium-catalyzed cross-coupling reactions of arylsilanolates.

Through the combination of reaction kinetics (both stoichiometric and catalytic), solution- and solid-state characterization of arylpalladium(II) arylsilanolates, and computational analysis, the intermediacy of covalent adducts containing Si-O-Pd linkages in the cross-coupling reactions of arylsilanolates has been unambiguously established. Two mechanistically distinct pathways have been demonstrated: (1) transmetalation via a neutral 8-Si-4 intermediate that dominates in the absence of free silanolate (i.e.

Cross-coupling reactions of arylsilanols with substituted aryl halides.

[reaction: see text] The palladium-catalyzed cross-coupling of arylsilanols with aryl iodides and aryl bromides (in the presence of cesium carbonate) furnished various biaryl products in high yield. An extensive series of optimizations led to the identification of key variables, including activator, solvent, catalyst, and hydration level, that influence the rate and selectivity of the process. Manipulation of these features provided an effective coupling method of wide scope and generality.