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 1-phenyl-2-thio-hydanroin (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, H-1 NMR, F-19 NMR and mass spectral studies. All the compounds have been screened in vitro for antifungal activity against Alternaria alternata.