Gold-Catalyzed Regiodivergent Annulations of Diazo-Alkynes Controlled by Et3N(HF)3

Selectivity control in catalytic carbene insertions is known to be dominated by the adjustment of both the electronic and steric properties of metal complexes. Herein, we report a conceptually distinct strategy that enables a regioselectivity switch for the gold-catalyzed carbohydroxylation of diazo-tethered alkynes controlled by the additive Et3N­(HF)3. Depending on the reaction conditions, either direct carbohydroxylation is observed or Michael addition/1,2-shift of the quinoid carbene intermediate in the presence of a Brønsted acid is involved. In both cases, the reaction proceeds with high regioselectivity. We also describe an intramolecular cascade fluorination process for the synthesis of aryl fluorides in high yield, which can be triggered under inert conditions and the use of Et3N­(HF)3.