Synthesis of Spirooxindole‐Benzo[d]oxazoles and Dihydrobenzofurans through Cycloaddition and Rearrangement of N‐Vinyl Nitrones and Arynes.

Various spirooxindole‐benzo[d]oxazoles and dihydrobenzofurans were prepared in good to excellent yields by [3+2] cycloaddition and selective rearrangement of N‐vinyl oxindole nitrones and arynes under transition metal‐free conditions. Experimental results showed that the substituent on the nitrone N‐vinyl group controlled the [1,3]‐ or [3,3]‐rearrangement of their cycloadduct owing to its steric effect. The present method features broad substrate scope, good functional group tolerance, controllable [1,3]‐ or [3,3]‐rearrangement, and diverse oxindole scaffolds. [ABSTRACT FROM AUTHOR]