Direct Synthesis of Diverse 3-Dialkylaminoallylideneindolin-2-ones.

The rhodium-catalyzed reaction of 1-alkyl-3-diazoquinoline-2,4-diones and enaminones directly constructs structurally diverse 3-(3-dialkylaminoallylidene)indolin-2-ones in satisfactory to excellent yields. The reaction involves the rhodium-catalyzed ring-contractive Wolff rearrangement of 3-diazoquinoline-2,4-diones followed by the [2 + 2] annulation of the generated cyclic acylketenes with enaminones and final [2 + 2] cycloreversion. Two separate Hammett plots in the linear free energy analysis were observed for the reaction and rationalized by DFT calculations. The reaction features readily available starting materials, high atom economy, and convenient derivations of medicinal molecules.