MEDIATING REAGENTS BRIDGE THE GAP FOR CF_2 TRANSFER

摘要

Researchers on the hunt for new synthetic pathways to develop novel fluorochemicals have recently turned to an old friend for a new purpose. Trifluoromethyl trimethylsilane (TMSCF_3), which has been utilized for decades in the addition of CF_3, is now being used to incorporate CF_2 into organic molecules. However, before such a reaction can be developed on a larger, potentially industrial scale, the kinetics and mechanism behind it must be further understood. Guy Lloyd-Jones, Andrew Leach, and co-workers have studied the addition of CF_2 to alkenes and alkynes, uncovering the crucial role that the substoichiometric initiators, TBAT and NaI, play in liberating CF_2 from the TMSCF_3 reagent (DOI: 10.1021/jacs.0c06751). The team's work, using stopped-flow NMR and computation, has detailed how the reaction's essential destabilizing a CF_3-anionoid depends on the initiator used. While both initiators facilitate the final reaction, their mechanisms differ greatly. TBAT results in a reaction that has well-defined kinetics but becomes progressively inhibited in unproductive side reactions. NaI, however, induces chain-branching-driven auto-acceleration, leading to unpredictable kinetics but highly efficient generation of the desired products. This study's insight into these two disparate mechanisms will be valuable in the development of techniques that incorporate CF_2 reactions into industrial processes.