Synthesis of Indole-Fused Dihydrothiopyrano Scaffolds <i>via</i> (3 + 3)-Annulations of Donor–Acceptor Cyclopropanes with Indoline-2-Thiones
Braj Gopal, Prasoon Raj Singh, Madan Kumar, Avijit Goswami
Abstract
A new methodology for the synthesis of N-haloindole-fused dihydrothiopyrano derivatives via (3 + 3)-annulation of donor–acceptor cyclopropanes (DACs) with indoline-2-thiones in the presence of Sc(OTf)3 as a Lewis acid catalyst has been developed. This protocol provides a variety of indole-fused dihydrothiopyrano molecules in good to excellent yields, which architecturally resemble other indole-fused tricyclic molecules having potential medicinal value. In addition, we have described a detailed reaction mechanism and transformation of the furnished product into N-fused thiazino indole molecule.
Topics & Concepts
IndolineAnnulationIndole testChemistryCombinatorial chemistryMoleculeCatalysisStereochemistryAcceptorRing (chemistry)Organic chemistryCondensed matter physicsPhysicsCyclopropane Reaction MechanismsSulfur-Based Synthesis TechniquesCatalytic C–H Functionalization Methods