crosscouplingtype

Cross-coupling type refers to a family of catalytic reactions in organic chemistry that form a new covalent bond between two fragments by joining them in the presence of a transition-metal catalyst, typically palladium or nickel. The typical partners are an organic electrophile, such as an aryl or vinyl halide or triflate, and a nucleophilic reagent generated from an organometallic species. These reactions are valued for their ability to construct carbon–carbon bonds and, in some variants, carbon–heteroatom bonds under relatively mild conditions and with broad functional-group tolerance.

Most cross-coupling mechanisms share a catalytic cycle that includes oxidative addition of the electrophile to the metal center, transmetalation with the nucleophilic partner, and reductive elimination to form the coupled product and regenerate the catalyst. Ligand choice, base, solvent, and additives strongly influence rate, selectivity, and functional-group compatibility.

Representative cross-coupling types include Suzuki–Miyaura coupling, which uses organoboron reagents with aryl or vinyl halides; Negishi coupling, employing organozinc reagents; Kumada coupling, using Grignard reagents; Stille coupling, involving organotin reagents; Sonogashira coupling, which combines terminal alkynes with aryl or vinyl halides (often with copper co-catalysis); Heck reaction, which couples aryl or vinyl halides with alkenes; and Hiyama coupling, using organosilicon reagents. Each type offers distinct advantages and limitations related to reagent availability, toxicity, and substrate scope.

Applications span pharmaceutical synthesis, agrochemicals, and materials science, where precise construction of carbon–carbon backbones is essential. Limitations include moisture or air sensitivity for some reagents, environmental and handling concerns for certain coupling partners, and the need for carefully chosen catalysts and conditions to maximize yield and minimize side reactions.