NiH‐Catalyzed Migratory Defluorinative Olefin Cross‐Coupling: Trifluoromethyl‐Substituted Alkenes as Acceptor Olefins to Form
<i>gem</i>
‐Difluoroalkenes
a NiH-catalyzed migratory defluorinative coupling between two electronically differentiated olefins. A broad range of unactivated donor olefins can be joined directly to acceptor olefins containing an electron-deficient trifluoromethyl substituent in both intra- and intermolecular fashion to form gem-difluoroalkenes. This migratory coupling shows both site- and chemoselectivity under mild conditions
Monofluoroalkenylation of Dimethylamino Compounds through Radical–Radical Cross‐Coupling
作者:Jin Xie、Jintao Yu、Matthias Rudolph、Frank Rominger、A. Stephen K. Hashmi
DOI:10.1002/anie.201602347
日期:2016.8
An unprecedented and challenging radical–radicalcross‐coupling of α‐aminoalkyl radicals with monofluoroalkenyl radicals derived from gem‐difluoroalkenes was achieved. This first example of tandem C(sp3)−H and C(sp2)−F bond functionalization through visible‐light photoredox catalysis offers a facile and flexible access to privileged tetrasubstituted monofluoroalkenes under very mild reaction conditions
which otherwise are essentially reluctant towards F‐nucleoplilic addition, now readily participate in this fluoroallylation reaction. Furthermore, this strategy provides an elegant example for the generation, as well as functionalization, of α‐CF3‐substituted benzylic radical intermediates using cheap and readily available starting materials.
Photocatalytic syntheses of gem-difluoroolefins were performed using the B12–TiO2 hybrid catalyst during the CC bondreduction of α-trifluoromethyl styrenes with C–F bondcleavage at room temperature under nitrogen. The gem-difluoroolefins were used as synthetic precursors for fluorinated cyclopropanes.