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2‐Carboxy‐1‐alkylindole‐3‐acetic acid anhydrides (I) condensed with S‐methylisothiosemicarbazide in DMF to form 5,11‐dihydro‐6‐methyl‐2‐methylthioindolo[3′,2′:4,5]pyrido[1,2‐b]‐s‐triazol‐5‐one (II). Compound II underwent ring opening on refluxing with sodium hydroxide solution to give IV. The anhydride I reacted with primary amines in benzene to give 2‐carboxy‐1‐alkylindole‐3‐acetanilide derivatives (VI) which yielded l‐methylindole‐3‐acetic acid by decarboxylation followed by hydrolysis. Compound II oxidised to the diketo compound X which could be prepared by the hydrolysis of the azomethine derivative IX with acetic acid‐hydrochloric acid mixture. Compound II reacted with benzyl chloride to yield the dibenzyl derivative XII, condensed with p‐chlorobenzaldehyde to form the 11‐p‐chlorobenzylidene derivative XI and coupled with arenediazonium salt to give the 11‐arylhydrazone derivatives XIII.

2-Mercapto-4-amino-5-cyano-6-arylpyrimidines (1a, b), 2-hydroxy derivatives 1c, d and 2-methylmercapto derivatives 4 a, b were synthesised via the reaction of either a mixture of malononitrile and aromatic aldehyde or arylidene malononitrile with thiourea, urea and S-methylisothiourea, respectively. 1c, d could also be obtained by the action of hydrogen peroxide on 1a, b or by the action of hydrochloric acid on 4a, b. Compounds 4a, b could also be prepared by the action of methyl iodide on 1a, b. 4a reacted with hydrazine hydrate to give the 2-hydrazino derivative 5 which condensed easily with aromatic aldehydes to give the Schiff’s bases 6 a, b. Compound 5 could be converted into the tetrazolo-and s-triazolopyrimidines 7 and 9 by the action of nitrous acid and carbon disulphide respectively. Structures of the newly synthesised compounds were established by chemical routes and spectral studies