Enantioselective α-Arylation of Carbonyls via Cu(I)-Bisoxazoline Catalysis
摘要:
The enantioselective alpha-arylation of both lactones and acyl oxazolidones has been accomplished using a combination of diaryliodonium salts and copper catalysis. These mild catalytic conditions provide a new strategy for the enantioselective construction and retention of enolizable alpha-carbonyl benzylic stereocenters, a valuable synthon for the production of medicinal agents.
Weak force in action: In the title reaction, the palladium catalyst (see figure, left) uses weak CH⋅⋅⋅O hydrogen bonding to control the absolute configuration of the new stereocenter. A similar palladium catalyst (right) used conventional NH⋅⋅⋅O hydrogen bonding to guide stereoselection.