共查询到17条相似文献,搜索用时 593 毫秒
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以冰乙酸为催化剂,将取代吡唑甲醛和巴比妥酸或硫代巴比妥酸在无水乙醇中进行Knoevenagel缩合反应,合成了6个5-(取代吡唑基-4-次甲基)(硫代)巴比妥酸。标题化合物经IR、1^HNMR、元素分析确证结构。 相似文献
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室温离子液体促进的5-亚芳基巴比妥酸衍生物的合成 总被引:1,自引:0,他引:1
在室温离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)存在下, 采用室温研磨和微波辐射的方法, 由芳香醛和巴比妥酸或硫代巴比妥酸经Knoevenagel缩合反应, 制备了相应的5-亚芳基巴比妥酸或5-亚芳烃基硫代巴比妥酸衍生物. 在室温研磨条件下反应2 h, 产率为78%~96%, 在微波辐射功率为160 W时反应20 s, 产率为82%~98%, 产物结构经1H NMR确证. 相似文献
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5-(吲哚基-3-次甲基)(硫代)巴比妥酸的合成 总被引:1,自引:0,他引:1
以冰乙酸为催化剂,吲哚-3-甲醛与巴比妥酸或硫代巴比妥酸在无水乙醇中进行Knoevenagel缩合,合成了5-(吲哚基-3-次甲基)巴比妥酸或5-(吲哚基-3-次甲基)(硫代)巴比妥酸,其结构经1H NMR和IR表征. 相似文献
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设计并合成了3种含有巴比妥酸基团的具有电子给-受体结构的两亲性有机分子,经元素分析、红外光谱、核磁共振谱确定了其结构,研究了醛与巴妥酸缩合的条件及醛的反应活性与其IR、NMR谱的关系. 相似文献
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NMR reaction following experiments were used to find optimal conditions for the barbituric acid double addition to aromatic and heteroaromatic carboxaldehydes. It was established that aromatic aldehydes with electron‐donating substituents such as hydroxy, methoxy, and dimethylamino produce only the single addition barbituric acid adduct (barbituric acid benzylidenes). If these electron‐donating substituents are transformed into electron‐withdrawing substituents by virtue of protonation (NMe2 to NHMe2+) then the double barbituric acid adduct becomes the sole product of the reaction. This is also true regardless of the reaction media if strong electron‐withdrawing substituents (such as a nitro group) are present. Considering that the reactive species for nitrogen containing aromatic heterocycles are actually the conjugated acids (electron deficient molecule) only the double barbituric acid adducts are isolated. All synthetic procedures presented are applicable to multi‐gram scale preparations of double barbituric acid adducts. 相似文献
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A simple and efficient synthesis for the preparation of unusual charge‐separated pyridinium (thio)barbiturate zwitterion derivatives was achieved via a one‐pot reaction of (thio)barbituric acid derivatives and 2‐pyridinecarbaldehyde under solvent‐free condition and also in methanol under refluxing. The structure of the compounds was confirmed by 1H NMR, 13C NMR, FT‐IR, mass and X‐ray analysis. The mechanism of the formation is discussed. Instead, no related pyridinium zwitterion was afforded from the reaction between dimedone and 2‐pyridinecarbaldehyde under the same conditions and its xanthene derivative was obtained. 相似文献
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This work shows the modification of barbituric acid (BA) chemical shifts by dimethylsulphoxide (DMSO) molecules. The discussed
changes are caused by creation of the H-bonded associates formed by barbituric acid with DMSO in solution. Free molecule of
barbituric acid, the cluster of BA with two DMSO molecules and two different clusters of BA with four DMSO units are taken
into consideration. The chemical shifts of these systems have been calculated and the obtained results have been compared
with experimental data. Theoretical calculations predict a significant downfield shift for imino protons of barbituric acid
involved in intermolecular-N-H...DMSO hydrogen bonds. The influence of the solvent molecules on other nuclei chemical shifts,
especially protons of barbituric acid methylene group, is also reported.
The calculations have involved Hartree-Fock and several Density Functional Theory methods. All methods correctly describe
experimental 1H and 13C NMR spectra of barbituric acid. The best consistence between experiment and theory is observed for the BLYP functional.
Four approximations of magnetic properties calculations embedded in the Gaussian’98 package have been tested. The results
of the performed calculations indicate that from a practical point of view the GIAO method should be preferred. 相似文献
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Spiro-fused heterocycles were synthesized in good to high yields by a pseudo four-component reaction of an aldehyde, urea and a cyclic β-diester or a β-diamide such as Meldrum’s acid or barbituric acid derivatives using microwave irradiation under solvent-free conditions. 相似文献
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Cotarnine was reacted with barbituric acid and its N-alkylbartituric and 1,3-dimethyl-2-thio analogs under forcing conditions to produce spirocyclic systems. Adducts, further
transformations of which included skeletal rearrangements (a type of T-reaction) and subsequent deamination, were formed in
the first step. The reaction of N-methylcotarnine and 1,3-dimethylbarbituric acid was analogous. The properties of the spirocyclic products were studied. They
were further modified at the CH-acid and aromatic moieties.
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Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 38–42, January–February, 2008. 相似文献
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ASHNAGAR Alamdar GHARIB NASERI Nahid SHEERI Behrang 《中国化学》2007,25(3):382-384
Knovenagel reaction of barbituric acid with different aldehydes were used to synthesize new barbiturates. This is a novel method which can be used to synthsis various types of new generation of barbiturates which are different from the previously reported. 相似文献