Metal-Free One-Pot Annulative Coupling of 2-Hydroxybenzaldehydes with β-Ketothioamides: Access to Diverse 2-Arylimino-2<i>H</i>-Chromenes
Pragya Pali, Dhananjay Yadav, Subash C. Sahoo, Maya Shankar Singh
Abstract
A concise and practical one-pot sustainable approach for expedient synthesis of 2-arylimino-2H-chromenes by two-component cascade [4 + 2] annulative coupling of easily available 2-hydroxybenzaldehydes with β-ketothioamides has been developed in good yields for the first time. Remarkably, metal- and additive-free conditions, use of simple K2CO3 as a mild base, open atmosphere, exclusive regioselectivity, step/atom economy, nonhazardous reagents, and easy purification are added characteristics to the strategy. This annulative protocol will not only provide an efficient method to access diverse chromene scaffolds, but also enrich the research domain of β-ketothioamides.
Topics & Concepts
ChemistryRegioselectivityReagentAtom economyCombinatorial chemistryCascadeBase (topology)Component (thermodynamics)Coupling (piping)Organic chemistryCatalysisChromatographyMechanical engineeringMathematical analysisMathematicsEngineeringThermodynamicsPhysicsSynthesis and biological activitySynthesis of heterocyclic compoundsSynthesis and Characterization of Heterocyclic Compounds