Arynes are extremely versatile and highly reactive electrophilic intermediates. While they offer virtually unparalleled versatility in terms of reactivity, the control over the regioselectivity with which arynes react remains challenging. Regiocontrol of aryne captures is typically achieved using comparatively simple and/or chemically inutile substituents adjacentto the reactive triple bond. This poses a challenge for the broad acceptance of arynes as the basis of genuinely useful synthetic building blocks for the constraction of more complex structures.1-3 Our research attempts to overcome this limitation by developing a strategy in which the functional group that drives the regioselectivity2-3 of an aryne capture is installed at a remote location of the molecule and offers ample opportunity for further derivatisation. This has been achieved via a catalytic C-H borylation strategy of trimethylsilylil aryltriflates (readily available aryne precursors) previously demonstrated by our group.4 Using experimental, mechanistic and computational studies, we show that a distal, boron-based functional group is temporarily activated in-situ into a form able to furnish unprecedented levels of aryne capture regioselectivity. We show the possibility to use this boronate in a single pot aryne capture/cross-coupling reaction to afford complex heterocyclic structures in a simple fasion, that would be otherwise difficult to synthesisze. Furthermore, we demonstrate that the in situ generated boronate is able to reverse the inherent regioselectivity of certain arynes in aryne capture reactions.

Remote regiocontrol of aryne capture by an in-situ formed boronate

ACS Fall 2021

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