Synthesis of novel pentacyclic thiopyrano indole-annulated benzo-δ-sultone derivatives via a domino Knoevenagel-hetero-Diels-Alder reaction in water

An efficient synthesis of novel pentacyclic thiopyrano indole-annulated benzo-delta-sultone derivatives is achieved via intramolecular domino Knoevenagel-hetero-Diels-Alder reaction of 2-formylphenyl (E)-2-phenylethenyl sulfonates and indoline-2-thiones in aqueous medium. The products are formed in good yields with high regio- and stereoselectivity. (c) 2013 Elsevier Ltd. All rights reserved.