Synthesis Of Pyrimido Research Articles

Ring closure reaction of 4‐(2‐hydroxyanilino)‐2‐phenyl‐5‐pyrimidinecarboxylic acid with acetic anhydride. Synthesis of pyrimido[5,4‐c] [1,5]benzoxazepin‐5(11H)ones

AbstractSyntheses of 11‐acety1‐2‐phenylpyrimido[5,4‐c][1,5]benzoxazepin‐5(11H)one (16a) and analogs (16b,c, 22) were described. The reaction of 4‐chloro‐2‐phenyl‐5‐pyrimidinecarboxylic acid ethyl ester (7) with 2‐aminophenol afforded 4‐(2‐hydroxyanilino)‐2‐phenyl‐5‐pyrimidine‐carboxylic acid ethyl ester (8a). The latter was also prepared by catalytic reduction of 4‐(2‐nitrophenoxy)‐2‐phenyl‐5‐pyrimidinecarboxylic acid ethyl ester (9), which was obtained from 7 and 2‐nitrophenol. Involvement of 4‐(2‐aminophenoxy)‐2‐phenyl‐5‐pyrimidinecarboxylic acid ethyl ester (12a) in this reduction as an intermediate was demonstrated by an independent synthesis of 12a and its subsequent rearrangement to 8a. Hydrolysis of 8a or 12a gave 4‐(2‐hydroxyanilino)‐2‐phenyl‐5‐pyrimidinecarboxylic acid (15a). Reaction of 15a with acetic anhydride afforded 16a, the first member of a novel ring system, the pyrimido[5,4‐c][1,5]‐benzoxazepin. Additional examples (16b,c) were prepared similarly. The corresponding 11‐ethyl derivative (22) was prepared in similar fashion, starting with 7 and 2‐ethylaminophenol. A possible reaction mechanism for the formation of 16a‐c from 15a‐c and acetic anhydride was discussed.

Pyrimidines. Part XXIII. Synthesis of pyrimido[4,5-b][1,4]oxazines by reaction of 4,5-diaminopyrimidine derivatives with α-halogeno-ketones

Condensation of certain 4,5-diaminopyrimidine derivatives with α-bromoisopropyl methyl ketone is shown to give pyrimido [4,5-b][1,4]oxazines and not the expected dihydropteridine derivatives. Similar condensations with a number of different α-halogeno-aldehydes and α-halogeno-ketones have been studied, and the factors which control the nature of the product have been determined. Some preliminary studies of the chemical reactivity of pyrimido-[4,5-b][1,4]oxazines have been carried out.

アミノキノリン誘導体の合成研究(第6報) : Pyrimido[1,2-α]quinoline誘導体の合成

アミノキノリン誘導体の合成研究(第6報) : Pyrimido[1,2-α]quinoline誘導体の合成

The synthesis of pyrimido[4,5‐d] pyridazines

AbstractThe synthesis of pyrimido[4,5‐d]pyridazin‐2‐one‐4‐thione (II), pyrimido[4,5‐d]pyridazine‐2,4‐dithione (VI), 4‐aminopyrimido[4,5‐d]pyridazine‐2‐thione (III), 2‐aminopyrimido[4,5‐d]‐pyridazin‐4‐one (X), 2‐methylpyrimido[4,5‐d]pyridazin‐4‐one (XII), and pyrimido[4,5‐d]‐pyridazin‐4‐one (XIII) are reported together with several new pyridazine intermediates.

The synthesis of pyrimido[4,5‐c]pyridazines and pyrimido[5,4‐c]pyridazines

AbstractThe Hofmann reaction on 6‐methylpyridazine‐3,4‐dicarboxamide (1) gave a mixture of 3‐methylpyrimido[4,5‐c]pyridazine‐5,7‐dione (2), 3‐methylpyrimido[5,4‐c]pyridazine‐6,8‐dione (3) and an acid (4) of unknown structure. The Hofmann reaction on pyridazine‐3,4‐dicarboxamide (9) gave a mixture of pyrimido[4,5‐c]pyridazine‐5,7‐dione (10) and an acid (11) of unknown structure. The reaction of 3‐amino‐6‐methylpyridazine‐4‐carboxamide (18) with ethyl orthoformate gave 3‐methylpyrimido[4,5‐c]pyridazin‐5‐one (21). 4‐Aminopyridazine‐3‐carboxamide (36) upon fusion with urea gave pyrimido[5,4‐c]pyridazine‐6,8‐dione (37) while with ethyl orthoformate 36 gave pyrimido[5,4‐c]pyridazin‐8‐one (38). Pyrimido[5,4‐c]‐pyridazine‐8‐thione (39) was obtained by the action of phosphorus pentasulfide on 38. 4‐Amino‐3‐cyanopyridazine (16) when treated with formamide produced 8‐aminopyrimido[5,4‐c]‐pyridazine (41). The synthesis of 4‐aminopyridazine‐3‐carboxamide (36) and 4‐amino‐3‐cyanopyridazine (16), both key intermediates in the synthesis of the novel pyrimido[5,4‐c]pyridazine ring system was accomplished by the Reissert reaction of 4‐aminopyridazine‐2‐oxides and subsequent conversion of the nitrile to the amide.

Synthesis of pyrimido[4, 5-b][1, 4]thiazine derivatives

Synthesis of pyrimido[4, 5-b][1, 4]thiazine derivatives