A Metal-free and Operationally Simple Radical Trifluoromethylative Borylation of Unactivated Alkenes

We herein describe a protocol to synthesize trifluoromethylated alkyl boronates from alkenes by the mutual activation of the Togni II and the bis(catecholato)diboron reagents in the absence of any catalyst and additives. This reaction enables synthesizing a series of trifluoromethylated alkyl boronates using unactivated alkenes, including natural products and drug derivatives, in a regioselective manner. Moreover, the synthetic utility of the boronic ester present in the product allows access to a range of trifluoromethyl containing compounds. The radical trapping and gas detection experiments reveal that the more Lewis acidic diboron reagent determines the rapid formation of trifluoromethyl and boron centered radicals. A simple and efficient protocol has been developed to generate a trifluoromethyl and boron centered radical under metal-free conditions by the synergetic interaction of highly Lewis acidic boron reagent with Togni reagent. This method establishes a new approach for the installation of trifluoromethyl and boron moiety to the unactivated alkenes simultaneously.image

Automated summary

We describe a protocol for synthesizing trifluoromethylated alkyl boronates from alkenes using the mutual activation of Togni II and bis(catecholato)diboron reagents without the need for a catalyst or additives. This method enables the regioselective synthesis of trifluoromethylated alkyl boronates from unactivated alkenes, including natural products and drug derivatives. The boronic esters in the product can be further used to access a range of trifluoromethyl containing compounds. The reaction mechanism involves the formation of trifluoromethyl and boron centered radicals, with the more Lewis acidic diboron reagent driving the rapid radical formation.