Transition-metals govern the catalytic organometallic cross-coupling area of organic synthesis. However, the industry relies on a narrow group of transition-metals, namely noble metals, which abundancy and toxicity issues must be addressed. Therefore, the development of low-cost, abundant and non-toxic catalysts for sustainable processes is necessary to have a better impact on the environment and our society. Bismuth, a main group element, is a viable option for such catalytic alternative. In this work our group reports for the first time that high-valent Bi(III)/(V) redox platform is a viable option to perform challenging catalytic transformations using arylboronic acid derivatives. Such bismuth redox cycle was achieved by mimicking the canonical organometallic catalytic steps of transition-metals. Transmetallation of arylboronic species to bismuth(III) salts allowed the formation of Bi–aryl bonds. Strong oxidant was necessary for Bi(III) species to undergo oxidative addition to yield organobismuth(V) salt, which, together with highly electron-withdrawing diarylsuflone ligands, unlocked various reductive elimination pathways. One of them is allowing to forge C(sp2)–F bonds catalytically from arylboronic esters in good yields, which is of capital importance, as fluorine-containing molecules find applications in medicinal, agrochemical, materials and radiolabeling chemistry. Furthermore, detailed experimental and theoretical mechanistic investigation of C(sp2)–F bond forming step from organobismuth(V) fluorides allowed us to improve the stoichiometric and catalytic protocols and expand the Bi(III)/(V) redox platform towards the reactivities beyond transition-metals. A rather unique catalytic oxidative C(sp2)–O coupling process was also developed, which employs weakly coordinating anions such as trifluoromethanesulfonate and nonafluorobutanesulfonate as coupling partners with arylboronic acids undergoing an umpolung at the ipso-carbon in an oxidative Ullman-type coupling to yield aryl triflates and nonaflates in good to excellent yields.

Catalytic C–heteroatom bond formation at a high-valent Bi redox platform

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.