2-Chloro-3-methylquinoxaline reacts with aromatic amines in basic medium forming 2-arylamino-3-methylquinoxalines, also it reacts with mercaptoacetic acid. The 3-methyl-2(1H)-quinoxalinone condenses with aromatic aldehydes forming the corresponding 3-(substituted styryl)-2(1H)-quinoxalinones which add bromine in acetic acid to yield the corresponding dibromo derivatives which react with morpholine, sodium methoxide, and piperidine to give the corresponding compounds. 3-Methyl-2(1H)-quinoxalinone undergoes side-chain bromination to yield 3-bromomethyl-2(1H)-quinoxalinone, which reacts with aromatic amines, sodium salt of saccharine, potassium phthalimide··· 3-Methyl-2(1H)-quinoxalinone with P2S5 gave 3-methyl-2(1H)-quinoxalinethione which reacts with 2-aminoethanol, dimethyl sulfate, and halo acids.

2-Hydrazinobenzoxazole (1), -benzimidazole (2), and benzothiazole (3) were condensed with ethyl chloroformate and/or diethyl oxalate to produce, 1,2,4-triazolo- and 1,2,4-triazino-fused ketones of the title azoles respectively. Condensation of 1 and 2 with aromatic aldehydes and/or acetic anhydride produced, 3-aryl- and 3-methyl-substituted 1,2,4-triazolo-fused azoles respectively. The hydrazines 1 and 2 cyclized with acetylacetone to produce the corresponding 2-(1-pyrazolyl) derivatives. 2-Acetylthiazolobenzimidazole reacted with hydroxylamine and/or alkylamines, to produce the corresponding condensation products. Also it condensed with aromatic aldehydes to give the chalcones. When reacted with benzenediazonium salt, it gave the corresponding 2-arylazo-substituted compounds.

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1‐(Phenylthio)‐ and 1‐(hydroxycarbonylmethylthio)‐4‐methylphthalazines were prepared from 1‐chloro‐4‐methylphthalazines (1). A series of 2‐benzyl‐ and benzenesulphonyl derivatives was prepared from the corresponding halides and 4‐methyl‐1(2H)‐phthalazinone (4). 4‐Methyl‐1(2H)‐phthalazinthione (6) was substituted at SH group to give 1‐(benzylthio)‐ and 1‐(ethoxycarbonylmethylthio)‐4‐methylphthalazines, 7 and 8 respectively. Treatment of hydrazine hydrate with 8 produced 1‐hydrazino‐4‐methylphthalazine (10). However, when the latter compound was treated with 1 it gave 1,2‐bis‐(4‐methylphthalazinyl)hydrazine. Treatment of 10 with aromatic aldehydes in glacial acetic acid gave the corresponding 3‐phenyl‐s‐triazolo‐[3,4‐a]‐6‐methylphthalazines 13. 1‐Hydrazino‐4‐methylphthalazine (10) underwent cyclization reactions with acetic anhydride, ethyl chloroformate, carbon disulphide, ethylformate, ethyl oxalate and with nitrous acid to give the corresponding triazolo‐, triazino‐ and tetrazolophthalazine compounds.

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