Enantioselective construction of triaryl-substituted all-carbon quaternary stereocenters <i>via</i> organocatalytic arylation of oxindoles with azonaphthalenes
Pengquan Chen, Mei-Jun Lv, Jun Kee Cheng, Shao‐Hua Xiang, Xiangzhong Ren, Junmin Zhang, Bin Tan
Abstract
Azonaphthalenes have been verified as a class of effective arylation reagents in a variety of asymmetric transformations. Here a highly efficient approach to construct triaryl-substituted all-carbon quaternary stereocenters through chiral phosphoric acid-catalyzed enantioselective arylation of 3-aryl-2-oxindoles with azonaphthalenes is disclosed. This chemistry is scalable and displays excellent functional group tolerance, furnishing a series of 3,3-disubstituted 2-oxindole derivatives in good yields with excellent enantiocontrol. Preliminary mechanistic data suggest that the initially formed direct addition intermediate undergoes intramolecular annulation under acidic reaction conditions.