Understanding existing and designing novel synthetic routes to Pd-PEPPSI-NHC and Pd-PEPPSI-PR3 pre-catalysts.

The reaction mechanism leading to the formation of cross-coupling palladium pre-catalysts of the PEPPSI family was investigated. Two intermediates were isolated and proved to be both suitable synthons to the pre-catalysts, with one permitting the design of a novel and greener user-friendly synthetic route. In light of this mechanistic understanding, the traditional one-pot method was shown to be possible using stoichiometric amounts of throw-away ligand, which represents a considerable synthetic improvement over the wasteful "in pyridine" approach.