A homogeneous Pd-catalyzed stereodivergent reduction of alkynes to Z and E alkenes by using H O as the H source is presented. Mediated by a diboron reagent, the transfer hydrogenation has been accomplished to yield the desired geometrical isomer by rational ligand selection. The switchable stereoselectivity achieved using simple phosphine ligands is generally excellent. D O has also been used as a D source for synthesizing the corresponding deuterated olefins. Supported by a gram-scale synthesis, the reaction can easily be scaled up making it an efficient way to prepare alkenes commercially as well. Mechanistic studies suggest formation of H-PdL -OAc as the crucial step leading to the presence of two pathways involving H-Pd-B(OR) and molecular H as active intermediates.

Tris(pentafluorophenyl)borane-catalyzed CÀC bond functionalization of arylallyl alcohols using donor-acceptor carbenes is presented. The allylic hydroxyl group is found to assist the product formation by neighboring group participation providing a clue towards mechanistic understanding. This method can also be employed to effect homologation of allyl alcohols to homoallyl alcohols. Overall, this metal-free transformation presents a novel disconnection strategy towards carbon-carbon bond scission and formation.

A carbene transfer reaction has been studied to understand the nature of the tris(pentafluorophenyl)borane stabilized donor-acceptor carbene. For this, a carbonate (or dicarbonate) molecule has been employed resulting in an overall carbonate functionality transfer. The results show that the diazo-derived carbenic carbon displays an electrophilic character. This also presents an opportunity to develop future carbene transfer reactions using a multitude of unconventional nucleophiles with the tris(pentafluorophenyl)borane catalyst.

A gold-catalyzed [2,3]-sigmatropic rearrangement reaction has been developed. The intermolecular rearrangement occurs between in situ generated donor-acceptor gold-carbenes and cinnamyl alcohols via tandem oxonium ylide formation. The desired rearranged product has been accomplished selectively over more conventional O-H insertion, cyclopropanation, cycloaddition, and C-H functionalization products under mild, open-air conditions. The scope of the work has been illustrated by synthesizing a new class of substrates that can be used for constructing complex molecular targets.

We present an approach to utilize water as the hydride source via Pd(II)/Pd(0) catalysis. As a case study, we have achieved a diboron mediated Pd(II)-catalyzed hydroarylation of alkynes using arylboronic acids. This approach not only complements conventional reactivity of Pd via Pd(0)/Pd(II) cycle for the hydroarylation but also utilizes water as the hydride source. We believe this would particularly be beneficial in utilizing water as a reagent.