- Synthesis of 2-dihydrooxadiazolinyl chromones
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Reactions of the substituted 2-formyl chromones with aroylhydrazines gave corresponding 2-(aroylhydrazonomethylidyne) chromones. Then 2-(3′-acetyl- 5′-aryl-2′,3′-dihydro-1′,3′,4′-oxadiazol- 2′-yl) chromones were prepared by these 2-(aroylhydrazonomethylidyne) chromones under refluxing with Ac2O. All target compounds were characterized through elemental analysis and IR, 1H NMR, MS.
- Cao, Ling-Hua,Cui, Peng-Yuan
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p. 903 - 908
(2007/10/03)
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- SOME REACTIONS OF 6-CHLORO-2-METHYL-4H-1-BENZOPYRAN-4-ONE. PART II
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6-Chloro-2-methyl-4H-1-benzopyran-4-one (I) gave the isoxazole derivative IIa on reaction with hydroxylamine hydrochloride. The action of hydrazine and phenylhydrazine on I resulted in pyrazole dervatives IIIa and IIIb, respectively. The reactivity of I with ethyloxalate and aromatic nitroso compounds have been investigated. Phthalide VIIIa derived from the chromone I was synthesised and rearranged easily into phthalone IX upon refluxing with alcoholic sodium methoxide. Cleavage of VIIIa with amines and hydrazine hydrate was studied. Thiation of phthalide VIIIa with either Lawesson's reagent or phosphorous pentasulphide yielded the corresponding thione VIIIe.
- Salem, Mounir A. I.,Hamed, Ashraf A.,El-Shekeil, Ali G.,Qui, A. S. Baba,Madkour, Hassan M. F.
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p. 605 - 618
(2007/10/03)
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- Synthesis and Reactions of Some 4-Oxo-4H-1-benzopyran-2-carboxaldehydes
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Some new 4-oxo-4H-1-benzopyran-2-carboxaldehydes (III) have been prepared, and the conversion of the 2-carboxaldehyde group in III into 2-carbonitrile and 2-carboxylic acid groups has been discussed.Unlike the general behaviour of the 4-oxo-4H-1-benzopyrans towards some nucleophiles, where the reaction takes place with opening of the pyronering, the 6-methyl- and 6-chloro-4-oxo-4H-1-benzopyran-2-carboxaldehydes (IIIa and IIIb) have been found to react with different nucleophiles such as hydroxylamine hydrochloride, hydrazine, phenylhydrazine and primary aromatic amines to give the corresponding condensation products (IV, VII, VIII, X, XI) without the opening of pyrone ring.The only exception to this observation is the reaction of IIIa and IIIb with ethylene diamine where the opening of pyronering does not take place to give the expected 5,6-dihydropyrazine derivatives (XIIa and XIIb).The reactions of IIIa and IIIb with active methylene compounds, malonic acid, malonodinitrile, cyanoacetic acid, ethyl cyanoacetate, cyanoacetamide and hippuric acid have also been discussed.
- Sami, S. M.,Ibrahim, S. S.,Abdel-Halim, A. M.,Aly, Y. L.
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p. 384 - 389
(2007/10/02)
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