Catellani reaction

[6] Thereafter, the Pd(II) species undergoes electrophilic cyclopalladation at the ortho position of the aryl group.

Subsequently, the palladacyclic intermediate undergoes a second oxidation addition with the alkyl halide coupling partner to form a Pd(IV) intermediate, which undergoes reductive elimination to forge the first C–C bond of the product.

After β-carbon elimination of norbornene, the resultant Pd(II) species then undergoes a second C–C bond forming step via a Heck reaction or cross coupling with an organoboron reagent to afford the final organic product and close the catalytic cycle.

[13][14] Likewise in the case of terminating ipso coupling partners with Heck-type termination with olefins,[1] Suzuki-type reaction with boronic esters,[9] borylation with bis(pinacolato)diboron,[10][15] protonation with i-PrOH,[11] decarboxylative alkynylation with alkynyl carboxylic acids.

[12] With tethered cross-coupling partners, Lautens, Malacria, and Catellani used this reaction to construct a variety of fused ring systems since 2000.