We report a direct C–H to C–C bond functionalization of electron-deficient heteroaromatics enabled by mild C–C bond cleavage of cyclopropanols as a new route to β-aryl carbonyl-containing products. Additionally, as an alternative to using a “catalyst” that requires an excess amount of a sacrificial oxidant for regeneration and/or oxidative aromatization, this paper features manganese(IV) oxide as an inexpensive “dual role” reagent – effecting both C–C bond cleavage and ultimate rearomatization. Under the specified conditions, a variety of heterocycles proved competent for regioselective C–C bond formation, alongside a diverse array of cyclopropanols with broad functional-group tolerance. We highlight applications to complex-molecule synthesis and direct derivatization of biologically active alkaloids. Furthermore, kinetic isotope effect (KIE) experiments, radical scavengers, and some insight into the application of tri- and tetravalent manganese species are invoked to shape an initial mechanistic hypothesis.

To expand upon the recent pioneering reports of catalyzed sp³ CH fluorination methods, the next rational step is to focus on directing “radical-based fluorination” more effectively. One potential solution entails selective CC bond activation as a prelude to selective fluorination. Herein, we report the tandem photocatalyzed ring-opening/fluorination reactions of cyclopropanols by 1,2,4,5-tetracyanobenzene (TCB) and Selectfluor to afford a process tantamount to site-selective β-fluorination of carbonyl-containing compounds. This new approach provides a synthetically mild and operationally simple route to otherwise difficult-to-prepare β-fluorinated products in good yields and with good-to-excellent regioselectivity. Remarkably, substrates that contain other usually reactive (e.g., benzylic) sites undergo ring-opening fluorination preferably. The versatility of this method to give cyclic β-fluorides from tertiary cyclopropanols and γ-fluoro alcohols is also highlighted.

Reported herein is the synthesis of a molecule containing an unusually strong hydrogen bond between an OH donor and a covalent F acceptor, a heretofore somewhat ill-defined if not controversial interaction. This unique hydrogen bond is to a large extent a product of the tight framework of the rigid caged system. Remarkably, the interaction shows little to no perceptible shift in the OH stretch of the IR spectrum relative to appropriate nonhydrogen-bound standards in fairly non-interactive solvents. This fascinating example of what has been termed a virtual “no-shift” hydrogen bond is investigated through NMR (coupling constants, isotopic chemical shift perturbations, proton exchange rates) and IR studies which all tell a consistent story.

Reported herein is the synthesis of a molecule containing an unusually strong hydrogen bond between an OH donor and a covalent F acceptor, a heretofore somewhat ill-defined if not controversial interaction. This unique hydrogen bond is to a large extent a product of the tight framework of the rigid caged system. Remarkably, the interaction shows little to no perceptible shift in the OH stretch of the IR spectrum relative to appropriate nonhydrogen-bound standards in fairly non-interactive solvents. This fascinating example of what has been termed a virtual “no-shift” hydrogen bond is investigated through NMR (coupling constants, isotopic chemical shift perturbations, proton exchange rates) and IR studies which all tell a consistent story.