N‑Protonated Acridinium Catalyst Enables Anti-Markovnikov Hydration of Unconjugated Tri- and Disubstituted Olefins

The preparation of alcohols with anti-Markovnikov selectivity directly from olefins and water is a sought-after reaction due to its atom-economy and potential cost-effectiveness. Herein, we present the first general method for direct, catalytic anti-Markovnikov hydration of unconjugated tri- and disubstituted olefins. The key advancement is made possible by an oxidative (E*_red = 2.15 V) N-H acridinium catalyst, which allowed for the functionalization of alkenes that were previously unreactive in such transformations due to their high oxidation potential. The developed protocol is not limited to hydration but also enables other hydrofunctionalizations, such as hydroetherifications, following the same mechanistic pathway.