The arylation or alkenylation of aldehydes with boronic acids is conveniently effected by a catalyst system comprising RhCl3⋅3 H2O (1 mol %), the sterically hindered imidazolium salt 2 (1 mol %), and a base. The N-heterocyclic carbene 6 derived from 2 is believed to be the actual ligand to the catalytically active rhodium species formed in situ. The method is compatible with various functional groups
Not only symmetrical, but also unsymmetrical α,α‐diaryl allylic alcohols are employed as substrates in the title reaction. A number of arenes and even heteroarenes underwent radical 1,2‐arylmigration (“neophyl rearrangement”) to produce α‐aryl β‐trifluoromethyl ketones. The preferential migration of electron‐deficient arylgroups over electron‐rich ones in unsymmetrical substrates supports the radical