Metal-Free Photoinduced Acylboration of [1.1.1]Propellane via Energy Transfer Catalysis
Saegun Kim, Hyunjung Oh, Weizhe Dong, Jadab Majhi, Mohammed Sharique, Bianca T. Matsuo, Sebastian Keeß, Gary A. Molander
Abstract
Highly strained 1,3-disubstituted bicyclo[1.1.1]pentanes (BCPs) have been established as bioisosteres of para -disubstituted benzene because they impart valuable pharmacokinetic properties. Herein, we demonstrate an energy transfer-mediated protocol for acylboration of [1.1.1]propellanes that allows the direct construction of various carbonyl species, such as carbamoyl-, carboxyl-, and acyl-, in tandem with synthetically versatile pinacol boronate (Bpin) groups onto the BCP substructure under simple reaction conditions. Moreover, drug-like molecules containing BCP boronates are further submitted to late-stage functionalization events. Several important transformations of the Bpin functional group of BCP boronates, including photoinduced cross-coupling reactions of BCP-BF 3 K, derived from BCP-Bpin, were successfully performed to showcase the synthetic utility. Additionally, diverse and elaborate mechanistic investigations were performed to provide mechanistic insights, and a plausible reaction mechanism is proposed.