Studies in spiroheterocycles. Part XVII. synthesis of novel fluorine containing spiro[indole‐pyranobenzopyran] and spiro[indenopyran‐indole] derivatives

An elegant one‐step synthesis of two novel spiro ring systems viz : spiro[3 H ‐indole‐3,4′‐(2′‐amino‐3′‐carbonitrile‐[4′ H ]‐pyrano[3,2‐ c ]benzopyran)]‐2,5′(1 H )‐dione8 and spiro[(2‐amino‐3‐carbonitrile‐indeno[1,2‐ b ]pyran)‐4(5 H )>3′‐[3 H ]indole]‐2′,5(1′ H )‐diones in 80–85% yields is described. The spiro heterocycles were prepared by the reactions of fluorine containing 3‐dicyanomethylene‐2 H ‐indol‐2‐ones with 4‐hydroxy‐2 H ‐1‐benzopyran‐2‐one and 1 H ‐indene‐1,3(2 H )‐dione respectively. The synthesized compounds have been characterized on the basis of elemental analyses, ir, pmr, 19 F nmr and mass spectral data.