Sodium salt of 4-hydroxy-6-methyl-2-phenylpyrimidine-5-carbonitrile (3) was subjected to alkylation with different a-halo compounds, where the corresponding O-alkylated products 4a-g were obtained. Ring closure of the O-alkylated product 4 a-c performed using sodium ethoxide in refluxing ethanol afforded furo[2,3d]pyrimidines 5a-c. The latter compounds on reaction with a variety of reagents gave other new furopyrimidines as well as a number of furodipyrimidines.

2-Hydrazino-3-phenyl-4(3H)-quinazolinone (1) underwent ring closure with aliphatic acid, aldehydes, and carbon disulfide to 1-alkyl-, 1-aryl-, and 1-mercapto-4-phenyl-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones (7) for instance. The 1-alkylthio-3-phenyl-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones were readily obtained from 7 and alkyl halides. Reaction of 1 with ethyl acetoacetate gave the corresponding hydrazone which was readily converted into 2-(3-methyl-5-oxo-2-pyrazolin-1-yl)-3-phenyl-4(3H)-quinazolinone.

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.

Die Benzylidenamino‐benzimidazole (I) reagieren mit Thioglykolsäure (II) zu den Tetrahydrothiazolonen (III) und mit den aus den Säurechloriden (IV) in situ erzeugten Ketenen zu den β‐Lactamen (V).

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