Recent Advances in the Synthesis and Reactivity of Isothiazoles

Abstract

AbstractIsothiazoles represent an important class of five‐membered sulfur heterocycles that are widely utilized in medicinal chemistry and organic synthesis due to the unique properties of two electronegative heteroatoms in a 1,2‐relationship. However, in contrast to other 1,2‐azoles, the facile assembly of isothiazoles has always been considered a substantial challenge. In the last decade, major advances have taken place in the fields of synthesis and functionalization of isothiazoles that make them accessible to a wide range of interested chemists through unprecedented pathways. New condensation methods have emerged that address the challenges posed by unstable thiohydroxylamine. New metal‐catalyzed approaches have been reported that deliver densely decorated isothiazoles bearing various sensitive functional groups. New functionalization strategies have been developed through both cross‐coupling and direct C−H activation chemistry. Finally, the emergence of novel heterocyclic architectures based on isothiazole opens the door for future investigations of this versatile heterocyclic scaffold. This review covers the period from January 2004 to December 2018 and is intended as a sequel to the review on isoxazoles, which represent another class of synthetically‐important 1,2‐azoles (see Adv. Synth. Catal. 2015, 357, 2583–2614).magnified image