Authors
Nada Saïdi, Thomas Simonet, Daniel P Kloer, Mark Montgomery, Myriem El Qacemi
Published in
Chimia. Volume 80. Issue 7-8. Pages 473-478. Aug 19, 2026. Epub Aug 19, 2026.
Abstract
Isothiazoles are valuable heterocycles in agrochemical and pharmaceutical research, yet they remain synthetically less accessible than their isoxazole counterparts. We report here a gold-catalyzed cyclization of propargylic N-tert-butanesulfinamides that provides direct and efficient access to isothiazoles under mild conditions. The transformation proceeds through an unusual cascade: cationic gold activation of the alkyne triggers a 5-endo-dig ring closure with sulfur as the nucleophile followed by irreversible loss of the tert-butyl group and dehydrative aromatization. The substrate scope encompasses a range of alkyl and aryl substituents, affording isothiazoles in yields of up to 79%. Reaction monitoring and isolation of key intermediates establish that the cyclic sulfinamide is a direct precursor to the aromatic product and that protic solvents, particularly acetic acid, facilitate the cascade of events, dramatically reducing reaction times. A complementary base-catalyzed pathway from CF3-substituted substrates selectively delivers cyclic sulfoximines, demonstrating that both heterocyclic classes are accessible from a common precursor by simply switching the activation mode. These results originate from a serendipitous observation made during insecticide research at Syngenta and have broader implications for the design of sulfur-containing heterocyclic scaffolds.
PMID:
42633626
Bibliographic data and abstract were imported from PubMed on 24 Aug 2026.
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