CU2O-Catalyzed C(SP3)-H/C(SP3)-H Cross-Coupling Using TEMPO: Synthesis of 3-(2-Oxoalkyl)-3-hydroxyoxindoles
摘要:
A simple, convenient, and efficient oxidative cross-coupling reaction of oxindoles with ketones toward a variety of 3-(2-oxoalkyl)-3-hydroxyoxindoles in moderate to excellent yields has been developed. This transformation proceeds via a tandem oxidative cross-coupling by using 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) in air as an environmentally benign oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C3 position of oxindoles.
In the presence of molecular sieve (MS) 4 Å in DMF, a catalyst-free aldol condensation of a variety of aromatic and aliphatic ketones with isatins under mild reaction conditions has been developed. This approach may provide access to a wide range of 3-substituted-3-hydroxyindolin-2-ones in good to excellent yields.