Efficient and convenient synthesis of methyl (S)-5-chloro-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylate: a key intermediate for (S)-indoxacarb using aqueous TBHP as oxidant†

Abstract

Indoxacarb is a novel broad-spectrum oxadiazine insecticide, and only (S)-indoxacarb is the active ingredient. (S)-5-Chloro-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylate is the key intermediate for synthesising (S)-indoxacarb. However, the current process for producing the intermediate is inconvenient and difficult to scale up. Herein, we report an improved protocol for the efficient, highly stereoselective and industrially feasible preparation of the intermediate, which features the use of tert-butyl hydroperoxide (TBHP, 70% in H₂O) as oxidant, purification by filtration and mild conditions.