Synthesis of Spiro(indenepyrazole) and Indenotriazinone Derivatives from 4-substituted Thiosemicarbazides and (1,3-dioxo-2,3-dihydro-1 H -Inden-2-Ylidene)Propanedinitrile

In a multistep reaction, N-substituted-5′-amino-4′-cyano-1,3-dioxo-1,3-dihydro-spiro[indene-2,3′-pyrazole]-2′(1 H) carbothioamides (63–71 %) and 4-substituted-3-thioxo-3 H-indeno[1,2- e][1,2,4] triazin-9(4 H)-ones (17–26 %) have been formed, from a series of 4-substituted thiosemicarbazides 1a–f with (1,3-dioxo-2,3-dihydro-1 H-inden-2-ylidene)propanedinitrile 3 in aerated ethyl acetate. Rationales of these conversions involving the nucleophilic reactions and condensation are presented.