A novel protocol for the palladium-catalyzed intramolecular direct arylation of benzoic acids is reported, which combines decarboxylation and C-H activation into one efficient process. With the optimized catalyst system of palladium trifluoroacetate, silver carbonate, and the proper solvent mixture (5% DMSO/dioxane), dibenzofuran derivatives are formed in excellent yield and selectivity.

A family of thiazolium salt derived N‐heterocyclic carbenes (NHCs) bearing sterically demanding aryl substituents on the nitrogen and with varying backbone substitution patterns have been synthesized. Investigation of the catalytic activity of these NHCs in a number of benzoin‐type coupling reactions revealed markedly different levels of reactivity and selectivity. To elucidate the underlying factors leading to differences in reactivity, a study of the electronic and steric properties of these NHC catalysts was conducted. By using the best catalyst in this study, the intermolecular cross‐benzoin condensation reaction was explored in more detail.

NHC‐catalysis proto(n)type: The title reaction produces 21 different chroman‐4‐one‐type products in good yields and excellent enantioselectivities, in each case building up a new all‐carbon quaternary stereocenter (see scheme). Based on DFT calculations a mechanistic scenario involving proton transfer, possible transition states, and a mode of enantioinduction is presented.

An intramolecular N-heterocyclic carbene (NHC)-catalyzed hydroacylation of unactivated double bonds is reported. Systematic variation of the catalyst structure revealed an N-mesitylthiazolylidene annulated with a seven-membered ring to be especially reactive. This NHC enables a unique C-C bond-forming reaction to afford substituted chroman-4-ones in moderate to excellent yields, even ones containing all-carbon quaternary centers.