Type: Article
A novel reaction between benzothiazoles and diaroylacetylenes in the presence of Meldrum's acid: ring expansion of benzothiazoles to functionalized 1,4-benzothiazines
Journal: Tetrahedron Letters (00404039)Year: 2009/08/05Volume: Issue: 31
DOI:10.1016/j.tetlet.2009.04.110Language: English
Abstract
A novel and efficient ring expansion of benzothiazoles to functionalized 1,4-benzothiazines is described. The reactive 1:1 zwitterionic intermediates formed by addition of benzothiazoles to diaroylacetylenes were trapped with Meldrum's acid under mild reaction conditions to produce 2-[2-hydroxy-2-aryl-2H-1,4-benzothiazin-3(4H)-yliden]-1-aryl-1-ethanones in excellent yields. © 2009 Elsevier Ltd. All rights reserved.