- Tricyclic Heteroaromatic Systems Containing a Bridgehead Nitrogen Atom. Part 3. Triazolopyrazolopyrimidines, Tetrazolopyrazolopyrimidines and Pyrimidopyrazolotriazines
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6-Phenyl-1H-pyrazolopyrimidin-3(2H)-one 16 has been prepared and converted into its 3-chloro 6, 3-thioxo 17 and 3-methylthio derivatives 9.Each of these could be converted into the 3-hydrazino derivative 3, cyclisation of which with carbon disulfide or triethyl orthoformate generated the fused 1,2,4-triazoles 23 and 20, respectively.Alternatively, the hydrazino derivative 3 gave a substituted hydrazide 26 or thiosemicarbazide 25, from which the 1,2,4-triazoles 21 and 22 respectively were obtained.The equilibrium between 3-azido-6-phenyl-1H-pyrazolopyrimidine 5 and 2-phenyl-9H-tetrazolopyrazolopyrimidine 27 was studied. 3-Diazo-4-methyl-6-phenyl-1H-pyrazolopyrimidine 29 was prepared by diazotisation of the corresponding amine 1 and converted into the 3-azido compound 4, which could not be cyclised to form a tetrazole.Finally, the diazo compound 29 readily formed the pyrimidopyrazolotriazine derivatives 32 and 33, when treated with pentane-2,4-dione and ethyl acetoacetate respectively.
- Golec, Julian M. C.,Scrowston, Richard M.,Dunleavy, Michael
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p. 239 - 244
(2007/10/02)
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- Reactions of Ethyl 4-Chloro-5-pyrimidinecarboxylates with 2-Aminopyridine. Synthesis of 5H-Pyridopyrimidopyrimidin-5-ones and 5H-Pyridopyrimidopyrimidin-5-ones and Rearrangement of the Former to the Latter
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5H-Pyridopyrimidopyrimidin-5-ones IVa,b and 5H-pyridopyrimidopyrimidin-5-ones Va,b were synthesized from ethyl 4-chloro-5-pyrimidinecarboxylate and 2-aminopyridine.The former compounds were obtained directly upon heating the reactants in ethanol, and the latter were prepared by the fusion of ethyl 4-(2-pyridylamino)-5-pyrimidinecarboxylates obtained as minor products from the above reaction.The angular fused cyclic compounds IVa,b were rearranged to the linear tricycles Vb-f upon heating with amines.
- Kim, Dong Han
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p. 173 - 176
(2007/10/02)
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- Antiallergy agents. I. 1,6-dihydro-6-oxo-2-phenylpyrimidine-5-carboxylic acids and esters
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The synthesis of some 1,6-dihydro-6-oxo-2-phenylpyrimidine-5-carboxylic acids and esters with potent oral and intravenous antiallergic activity against passive cutaneous anaphylaxis in the rat is described. Requirements for high activity include a free NH group in the pyrimidinone nucleus and a small to medium size ortho alkoxy or alkenyloxy group on the phenyl ring. It is suggested that in the case of the highly active compounds hydrogen bonding occurs between a nitrogen of the pyrimidine ring and the ethereal oxygen. The nature of this bonding and its possible contribution to an optimum configuration for the molecules is discussed.
- Juby,Hudyma,Brown,et al.
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p. 263 - 269
(2007/10/08)
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- Bis(4-[4'-hydroxy-5'-carboxy-2'-pyrimidinyl]phenoxy)alkanes
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5-Carboxypyrimidine derivatives and their pharmaceutically acceptable basic salts, and their use as antiallergy agents.
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