Pdcatalyzed

Pd-catalyzed refers to chemical reactions that are accelerated by palladium catalysts, typically enabling the formation of carbon–carbon bonds and, in some cases, carbon–heteroatom bonds under mild conditions. The central idea is a catalytic cycle in which palladium alternates oxidation states to facilitate bond construction and catalyst turnover. A hallmark of many Pd-catalyzed processes is cross-coupling, where two fragments are joined by a new bond through oxidative addition of a substrate to Pd, transmetalation with a nucleophilic partner, and reductive elimination to release the product and regenerate Pd(0).

The most prominent examples are palladium-catalyzed cross-couplings. Suzuki–Miyaura coupling links aryl or vinyl halides with boronic acids or esters; Negishi coupling uses organozinc nucleophiles; Stille employs organotin reagents; Kumada uses Grignard reagents. The Heck reaction couples aryl or vinyl halides with alkenes to give substituted alkenes, while the Sonogashira coupling connects aryl or vinyl halides with terminal alkynes (often with copper co-catalysis). These reactions are valued for broad substrate scope, functional-group tolerance, and scalability, contributing to pharmaceutical synthesis, agrochemicals, and materials science.

Catalysts typically feature palladium precursors such as Pd(PPh3)4 or PdCl2-based complexes paired with ligands (phosphines, N-heterocyclic carbenes) that modulate reactivity and selectivity. Advances include ligand design, new Pd sources, and expanded reaction types, such as Pd-catalyzed C–H activation and carbonylations. Limitations include cost, sensitivity to air or sulfur compounds, and contamination concerns in pharmaceutical contexts.

Historical note: palladium-catalyzed cross-coupling earned the 2010 Nobel Prize in Chemistry for Heck, Negishi, and Suzuki.