Dearomative Diazo [1,2]-Wittig Rearrangement/[1,2]-Migration Cascade: Synthesis of Quaternary 3-Aminooxindoles
1College of Chemistry (Pingyuan Laboratory), Zhengzhou University, Zhengzhou 450001, China.
None:
A dearomative diazo [1,2]-Wittig rearrangement/[1,2]-migration cascade has been developed for the efficient synthesis of quaternary 3-aminooxindoles from readily accessible indole-pyrazolone precursors. Under the catalysis of Sc(OTf)3, the reaction proceeds under mild conditions at room temperature, accommodating a broad range of substituents on both the indole and pyrazolone fragments. Mechanistic investigations support a pathway involving a diazo [1,2]-Wittig rearrangement, water-trapping, and a final [1,2]-migration. Furthermore, a preliminary asymmetric variant was achieved by using a chiral Pybox ligand with Cu(OTf)2.
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