Catalyst-free 1,6-conjugate addition of indoles and 4-hydroxycoumarins to<i>para</i>-quinone methides: synthesis of unsymmetrical triarylmethanes
Subramani Kumaran, Mohan Prabhakaran, Narayanan Mariyammal, Kanniyappan Parthasarathy
Abstract
The catalyst-free 1,6-conjugate addition of indoles and 4-hydroxycoumarins to para-quinone methides is reported. This protocol allowed us to access a range of unsymmetrical triarylmethanes in good to excellent yields. The outlined procedure is operationally simple, efficient, atom and step economical. The synthesized heterocyclic triarylmethanes were further converted into highly substituted indoloisoquinolines and pyranochromenones via metal-catalyzed C-H activation/annulation.
Topics & Concepts
ChemistryCatalysisAnnulationConjugateOrganic chemistryCombinatorial chemistryMathematicsMathematical analysisSynthesis of Indole DerivativesChemical Synthesis and ReactionsSulfur-Based Synthesis Techniques