Stable sulfonate esters as C1-synthons for cyclopropanation reaction to access antimicrobial active 3,3′-spirocyclopropyloxindoles†

Abstract

Alkyl sulfonyl chlorides widely serve as sulfene precursors to facilitate diverse transformations but suffer from poor hydrolytic stability under basic conditions, posing notable operational challenges. Consequently, the development of stable, easy-to-handle alternatives has garnered considerable interest for broad synthetic applications. Herein, we describe the efficient synthesis of spirocyclopropyloxindoles through a NaH-mediated formal [2 + 1] annulation using stable while reactive 4-nitrophenyl sulfonates as C1 synthons. Unexpectedly, the reaction proceeds through an unconventional [(2 + 2) − 1] pathway under basic conditions when using sulfonates and alkylidene oxindole substrates, deviating from conventional reaction modes. This approach affords spirocyclopropyloxindoles with high yields and good diastereoselectivity. Furthermore, these scaffolds demonstrate promising antibacterial activity against plant pathogens, highlighting their potential as novel agrochemical agents.