Copper-Catalyzed Enantioselective Arylation of 2-Methylacetoacetates

Significance

The authors have recently disclosed conditions for Ullmann couplings of aryl halides with active methylene compounds. In this report they describe the asymmetric variant between aryl iodides and β -keto esters by using CuI and trans-4-hydroxy-l-proline. The reaction temperatures are the lowest reported for Ullmann-type couplings. Many substituents on the aryl ring are tolerated, particularly electron-donating ones, which provide the highest yields and ee values. The products are pharmaceutically desirable since they contain α-aryl all-carbon quaternary centers. Conversion into oxindoles is also attainable in two steps, though the first step is low-converting.