Kinetic Analysis of Domino Catalysis: A Case Study on Gold-Catalyzed Arylation

Domino catalysis is a well-explored route to increasing the efficiency of multistep reactions. However, the kinetic features required for efficient turnover of a process where "multiple transformations are effected by a single catalytic mechanism"have not been explored in any detail. The kinetics of a nominally simple two-stage domino catalytic reaction have been analyzed by way of a gold-catalyzed coupling of two electron-deficient arylsilanes to generate an arylated fluorene. A combination of in situ interleaved 1H and 19F NMR spectroscopic kinetic measurements, kinetic simulations, and variations in substitution reveal how the catalyst partitioning between the two different cycles impacts both the rate and the selectivity of the process. The insight enables identification that sequential catalyst speciation and accumulation of the domino intermediate are general kinetic criteria for efficient domino catalysis.