共查询到20条相似文献,搜索用时 187 毫秒
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以乙酰乙酸乙酯和间苯二酚为原料,固体NaHSO_4·H_2O为催化剂,无溶剂条件下通过Pechmann反应合成7-羟基-4-甲基香豆素;并对反应温度、反应时间、催化剂用量、原料配比等因素对产率的影响进行了探究。实验证明,在无溶剂条件下,NaHSO_4·H_2O是合成7-羟基-4-甲基香豆素的良好催化剂,正交实验法得出反应的最优条件为:反应温度为110℃,反应时间40 min,n(间苯二酚)/n(乙酰乙酸乙酯)=1∶1.2,催化剂用量相对于间苯二酚用量的20%mol,产品的收率为81.8%。 相似文献
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以醛、吲哚和麦氏酸为原料,水和乙醇混合液为溶剂,在室温搅拌条件下以磷酸二氢钾为催化剂通过Yonemitsu缩合反应,合成了一系列的5-[(3-吲哚基)-芳甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物,产率为48%~98%,并通过X射线单晶衍射仪测定了化合物4o的晶体结构。 该方法能够有效的促使反应活性较低的4-甲基苯甲醛和4-甲氧基苯甲醛参与反应,以83%和60%的收率获得相应的目标产物,并具有反应条件温和、催化剂廉价易得、后处理简单、产物易于纯化、产率较高等优点,可用于合成3-取代吲哚类化合物。 相似文献
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Farnaz Jafarpour Nafiseh Jalalimanesh Mina Barzegar Amiri Olia Asieh Otaredi Kashani 《Tetrahedron》2010,66(49):9508-9511
A simple and highly efficient protocol with mild reaction conditions has been developed that allows the smooth protiodecarboxylation of diversely functionalized coumarin-3-carboxylic acids. In the presence of catalytic amounts of Ag2CO3 and acetic acid, even un-activated coumarin-3-carboxylic acids were converted in good to excellent yields and with great preparative ease to the corresponding coumarin derivatives. 相似文献
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Anindita Bhowmick Prof. Dr. Goutam Brahmachari 《European journal of organic chemistry》2023,26(15):e202300192
An efficient and straightforward protocol for accessing a new series of functionalized 4-aminocoumarins from PIDA/I2-mediated decarboxylative C4-amination of coumarin-3-carboxylic acids via direct Csp2−H dehydrogenative C−N cross-coupling with secondary amines under ambient conditions has been accomplished. The notable advantages of this protocol are the tolerance of diverse functional groups, mild reaction conditions at ambient temperature, moderate to good yields, short reaction times (in minutes), high regioselectivity, gram-scale applicability, and eco-friendliness. This is the first report of decarboxylative Csp2−H cross-dehydrogenative C−N coupling of coumarin-3-carboxylic acids for synthesizing 4-aminocoumarins. 相似文献
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Mehdi Khoobi Fatemeh Molaverdi Masoumeh Alipour Farnaz Jafarpour Alireza Foroumadi Abbas Shafiee 《Tetrahedron》2013,69(52):11164-11168
A protocol for straightforward and step-economical synthesis of neoflavones from coumarin-3-carboxylic acids is developed. This approach enables controlled protodecarboxylation/regioselective C–H arylation of coumain-3-carboxylic acids in one-pot using a monometallic catalytic system. A wide variety of electron-donating and -withdrawing substituents on both coumarins and arylboronic acid are tolerated under the reaction conditions and 4-aryl coumarins are constructed in high yields. 相似文献
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Majid M. Heravi Rahim Hekmatshoar Maryam Emamgholizadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1893-1896
Synthesis of substituted coumarin-3-carboxylic acids using the Knovenagel reaction of malonic acid and O-hydroxyaryl aldehydes supported onto HZSM-5 zeolite under microwave irradiation is described. 相似文献
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Leonardo Bonsignore Filippo Cottiglia Anna M. Maccioni Daniela Secci Silvio M. Lavagna 《Journal of heterocyclic chemistry》1995,32(2):573-577
The synthesis and isolation of some O-acylisoureas are described. The reaction between dicyclohexyl-carbodiimide and coumarin-3-carboxylic acids leads to coumarin-dicyclohexylisourea derivatives, isolated as the main products, and to coumarin-dicyclohexylurea derivatives as byproducts. 相似文献
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A simple synthesis of 2-(alkylamino)-5-{alkyl[(2-oxo-2H-chromen-3-yl)carbonyl]amino}-3,4-furandicarboxylates via a one-pot multi-component reaction is described. The reactive 1:1 zwitterionic intermediate generated from the addition of isocyanides to dialkyl acetylenedicarboxylates was trapped at room temperature by coumarin-3-carboxylic acids prepared in situ from a 2-hydroxy aromatic aldehyde and Meldrum’s acid to afford the title compounds in good to excellent yields. 相似文献
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The doubly decarboxylative Michael–type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described. 相似文献
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S. N. Kovalenko V. A. Zubkov V. P. Chernykh A. V. Turov S. M. Ivkov 《Chemistry of Heterocyclic Compounds》1996,32(2):163-168
It has been found that under the action of hydrazides of carboxylic acids, 2-iminocoumarin-3-carboxamides are recyclized to N(1)-acylamidrazones of coumarin-3-carboxylic acids. The use of N(1)-acylamidrazones is proposed as a simple and effective means of synthesizing 3-(1,3,4-oxadi-, thiodi-, and triazolyl-2)coumarins. The possibilities of alternate schemes of synthesis are discussed, and a mechanism is suggested for the recyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 186–192, February, 1996. 相似文献
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M. S. Frasinyuk S. P. Bondarenko O. V. Shablykina V. P. Khilya 《Chemistry of Heterocyclic Compounds》2011,47(9):1155-1163
The formylation of esters of 5-hydroxy-1-benzofuran-3-carboxylic acid has been studied. The interaction of the synthesized
aldehydes with esters of β-keto acids and hetarylacetonitriles gave furo[3,2-f]coumarin-1-carboxylic acids derivatives. 相似文献
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A simple, efficient, and green protocol for synthesis of coumarin-3-carboxylic acids is described via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes in [Hmim]Tfa ionic liquid, which was found to give better results than other ionic liquids. Furthermore, ionic liquid is easily reused without any appreciable loss in activity. 相似文献