A Base-Promoted Annulation Cascade: One-Pot Construction of C2-Spiropseudoindoxyls from 2-Nitrobenzaldehydes and Sulfonyl Hydrazones

A metal- and oxidant-free protocol for the construction of diverse C2-spiropseudoindoxyl derivatives from 2-nitrobenzaldehydes and readily prepared sulfonyl hydrazones has been developed. Mechanistic studies suggest an intramolecular addition/S N Ar/1,5-H shift sequence. This strategy delivers valuable C2-spiro-piperidine and -azetidine indolin-3-one scaffolds for bioactive molecule modification.