Synthesis of novel spiro[indole-pyranoimidazole] and spiro [indole-pyranopyrrole] derivatives

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "dejavu="" sans";mso-hansi-theme-font:minor-latin;mso-bidi-font-family:mangal;="" mso-bidi-theme-font:minor-bidi;color:#00000a;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">An elegant one-step synthesis of two novel spiro ring systems viz., spiro [3H-indole-3,4'(1’H)-pyrano[2,3-d-imidazol]-2-oxo-2'-thiones-5' carbonitrile (VI) and spiro[3H-indole-3,4'(1’H) pyrano [2,3-c] pyrrole]-5' carbonitrioles (VII) in 44-59% yields is described. The spiro heterocycles were prepared by the Michael reactions of 3-dicyanomethylene-2H-indol-2-ones (III) with I-phenyl-2-thio-hydamoin (IV) and 2-pyrrolidone/N-methyl-2-pyrrolidone (V), respectively, while the intermediate (III) has been synthesized from substituted indole-2,3-diones (I) with malanonitrile (II). The synthesized compounds have been characterized on the basis of elemental analyses IR' ¹<i>H</i> NMR ¹⁹F NMR and mass spectral studies. All the compounds have been screened in vitro for antifungal activity against <i style="mso-bidi-font-style: normal">Alternaria alternata</i>.</span>