SYNTHESIS OF NOVEL SPIRO[INDOLE-PYRANOIMIDAZOLE] AND SPIRO[INDOLE-PYRANOPYRROLE] DERIVATIVES

An elegant one-step synthesis of two novel spiro ring systems viz., sp iro[3H-indole-3,4'(1'H)-pyrano[2,3 -d-imidazol]-2-oxo-2'-thiones-5' ca rbonitrile (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 hetero cycles were prepared by the Michael reactions of 3-dicyanomethylene-2H -indol-2-ones (III) with 1-phenyl-2-thio-hydanroin (IV) and 2-pyrrolid one/N-methyl-2-pyrrolidone (V), respectively while the intermediate (I II) has been synthesized from substituted indole-2,3-diones (I) with m alanonitrile (II). The synthesized compounds have been characterized o n the basis of elemental analyses, IR, H-1 NMR, F-19 NMR and mass spec tral studies. All the compounds have been screened in vitro for antifu ngal activity against Alternaria alternata.