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/SNAr/1,5-H shift sequence. This strategy delivers valuable C2-spiro-piperidine and -azetidine indolin-3-one scaffolds for bioactive molecule modification.
Chen et al. (Fri,) studied this question.