The Ru-catalysed C2–H arylation of indoles and pyrroles by using boronic acids under oxidative conditions is reported. This reaction can be applied to tryptophan derivatives and tolerates a wide range of functional groups on both coupling partners, including bromides and iodides, which can be further derivatised selectively. New indole-based ruthenacyclic complexes are described and investigated as possible intermediates in the reaction. Mechanistic studies suggest the on-cycle intermediates do not possess a para-cymene ligand and that the on-cycle metalation occurs through an electrophilic attack by the Ru centre.

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(Pinacolato)boryl ortho-silyl(hetero)aryl triflates are presented as a new class of building blocks for arylation. They demonstrate unique versatility by delivering boronate or (hetero)aryne reactivity chemoselectively in a broad range of transformations. This approach enables the unprecedented postfunctionalization of fluoride-activated (hetero)aryne precursors, for example, as substrates in transition-metal catalysis, and offers valuable new possibilities for aryl boronate postfunctionalization without the use of specialized protecting groups.

A new, operationally simple approach is presented to access arynes and their fluoride-activated precursors based on Ru-catalyzed C−H silylation of arylboronates. Chromatographic purification may be deferred until after aryne capture, rendering the arylboronates de facto precursors. Access to various new arynes and their derivatives is demonstrated, including, for the first time, those based on a 2,3-carbazolyne and 2,3fluorenyne core, which pave the way for novel derivatizations of motifs relevant to materials chemistry.

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Aldimines and ketimines containing electron-donating and electron-withdrawing groups can be hydrosilylated with borenium catalysts at as low as 1 mol% catalyst loading at room temperature, providing the corresponding secondary amines...

This review discusses the preparation and orthogonal reactivity of boryl ortho-silyl(hetero)aryl triflates as precursors for arynes. These triflates undergo a wide variety of selective reactions of either the boronate or aryne component. Activation of the boronate group affords diverse (hetero)aryne precursors, whereas aryne activation and capture gives previously difficult-to-access arylboronates, all starting from the same set of common starting materials. Thus, the boronate and aryne functionality can be used for their mutual postfunctionalization with unprecedented flexibility.