共查询到20条相似文献,搜索用时 31 毫秒
1.
Srinivasa Reddy Narahari Buchi Reddy Reguri Omprakash Gudaparthi 《Tetrahedron letters》2012,53(13):1543-1545
Five percentage perchloric acid doped silica is successfully used as an efficient mild catalyst for the synthesis of 4-aryl dihydropyrimidine-2(1H)-ones. This method offers significant advantages such as efficiency and mild reaction conditions. 相似文献
2.
The Keggin heteropoly acid, silicotungstic acid, H4SiW12O40, has been demonstrated to be highly efficient for an expeditious, one-pot synthesis of 1-methyl-2-(hetero)arylbenzimidazoles from N-methyl-1,2-phenylenediamine and (hetero)aryl aldehydes in ethyl acetate at room temperature. The catalyst works equally well for N-phenyl-1,2-phenylenediamine. 相似文献
3.
Zeba N. Siddiqui 《Comptes Rendus Chimie》2013,16(2):183-188
A novel, greener approach was adopted for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives (4a–i) using bis[(L)prolinato-N,O]Zn as an inexpensive, efficient and mild Lewis acid catalyst in water. The methodology offers several advantages such as short reaction time, high yields, clean process, low loading of catalyst and simple operational procedure. The catalyst was active up to five cycles and was identified by SEM-EDX analysis. 相似文献
4.
《Comptes Rendus Chimie》2016,19(3):306-313
A simple, mild and efficient method is developed for the synthesis of 5-substituted 1H-tetrazoles. Out of three used Pb(II) catalysts, lead chloride (PbCl2) has been found to be an efficient catalyst for [3+2] cycloaddition of NaN3 with aromatic and aliphatic nitriles to afford 5-substituted 1H-tetrazoles. The catalyst is reusable up to four cycles with consistent activity. The cost effectiveness and easy availability of the catalyst, simple methodology, excellent yield and easy work-up are the additional advantages. 相似文献
5.
An efficient synthetic method for heterocycles containing both carbazole and 1,3,4-thiadiazole moieties is described. 9-Ethyl-9H-carbazol-3-carbaldehyde reacted with 4-arylthiosemicarbazides, with acetic acid as catalyst, to give 1-(9-ethyl-9H-carbazol-3-yl)methylene-4-arylthiosemicarbazides, which were further treated with manganese dioxide at room temperature in acetone to give 5-(9-ethyl-9H-carbazol-3-yl)-N-aryl-1,3,4-thiadiazol-2-amines in good to high yield. This procedure has the advantages of mild conditions, easy separation, and simple manipulation. 相似文献
6.
An efficient and practical one-pot synthesis of 3-substituted isoindolin-1-ones and isobenzofuran-1(3H)-ones has been developed under solvent free-conditions using non-toxic and cheap phenylboronic acid as excellent catalyst. This strategy involves the sequential two-step Mannich/lactamization cascade reaction of inexpensive 2-formylbenzoic acid with primary amines and a wide variety of ketones, and an aldol/lactonization cascade reaction of 2-formylbenzoic acid with a broad range of ketones. 相似文献
7.
《Mendeleev Communications》2022,32(5):624-626
Iron(iii) chloride has been found to serve as an efficient catalyst for a mechanochemical (ball milling) one-pot four- component cascade reaction of phenyl glyoxal, anilines, indoles and activated alkyne affording highly-substituted 3-(1H-pyrrol-2-yl)-1H-indoles. The procedure is beneficial because of mild conditions, easily available starting materials, cheap catalyst and possibility for scaling. 相似文献
8.
Ahmad Shaabani Mozhdeh Seyyedhamzeh Ali Maleki Fatemeh Hajishaabanha 《Tetrahedron》2010,66(23):4040-4167
5-Carboxamide substituted 3,4-dihydropyrimidine-2(1H)one derivatives were synthesized in a simple and efficient method from the one-pot four-component reactions of an aliphatic or aromatic amine, diketene, an aromatic aldehyde and urea or thiourea in the presence of p-toluenesulfonic acid as a catalyst under mild reaction conditions at ambient temperature. 相似文献
9.
M. M. Heravi A. Ghods F. Derikvand K. Bakhtiari F. F. Bamoharram 《Journal of the Iranian Chemical Society》2010,7(3):615-620
This is a report of an efficient, clean and facile method for the synthesis of 1,4-dihydropyrano[2,3-c] pyrazole and pyrano[2,3- d]pyrimidine derivatives via three-component one-pot condensation of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one or barbituric acid, aldehydes and malononitrile in the presence of a catalytic amount of preyssler type heteropolyacid as a green and reusable catalyst in water or ethanol under refluxing conditions. 相似文献
10.
1,3,5-Trihydroxyisocyanuric acid (THICA), which serves as an efficient radical-producing catalyst from hydrocarbons, was successfully prepared by two methods. The reaction of O-benzylhydroxyamine with phenyl chloroformate gave formbenzyloxycarbamic acid phenyl ester of which subsequent treatment with dimethylaminopyridine (DMAP) produced 1,3,5-tribenzyloxyisocyanurate leading to THICA by hydrogenation with H2 on Pd/C. The other method involved the direct synthesis of 1,3,5-tribenzyloxyisocyanurate from O-benzylhydroxyamine and diphenyl carbonate. The aerobic oxidation of p-methylanisole catalyzed using THICA as a key catalyst afforded p-anisic acid in almost quantitative yield (>99%). 相似文献
11.
P. SadanandamV. Jyothi M. Adharvana Chari Parthasarathi Das 《Tetrahedron letters》2011,52(42):5521-5524
We demonstrate the synthesis of various purine derivatives through the coupling of N4-methyl-2-morpholin-4-yl-pyrimidine-4,5-diamine with various aldehydes by using polyphosphoric acid (PPA) as an efficient catalyst in DMF at reflux temperature. The PPA catalyst gave better yields (70-85%) in short reaction times (45-60 min). This commercially available cheap catalyst is more active than many reported expensive catalysts. Many aldehydes underwent the above conversion to form a series of 9-methyl-2-morpholin-4-yl-8-phenyl-9H-purines. 相似文献
12.
Seyedeh Yasaman Afsar Ghodsi Mohammadi Ziarani Hoda Mollabagher Parisa Gholamzadeh Alireza Badiei Ali Abolhasani Soorki 《Journal of the Iranian Chemical Society》2017,14(3):577-583
An efficient one-pot synthesis of 2,3-dihydroquinazoline-4(1H)-one derivatives 4a–l is described using SBA-Pr-SO3H as a heterogeneous acid catalyst. The present methodology resulted in various derivatives of 2,3-dihydroquinazoline-4(1H)-one in good yield via a three-component reaction of isatoic anhydride, aldehydes and ammonium acetate. SBA-Pr-SO3H played a significant role as an efficient mesoporous catalyst due to its pore size of 6 nm. Additionally, UV–Vis spectrum of the products was studied in order to investigate their application as UV absorbers. 相似文献
13.
Pingli Lv Rongxiu Zhu Tongxiang Lu Steven E. Wheeler Dongju Zhang Ruoxi Wang Chengbu Liu 《Tetrahedron: Asymmetry》2013,24(24):1598-1604
Computational studies to determine the origin of enantioselectivity in the (1R,2R)-1,2-diphenylethane-1,2-diamine (DEPN)–Brønsted acid catalyzed epoxidation of 2-cyclohexen-1-one have been performed using density functional theory. Transition states for conjugate addition and ring closure steps of the epoxidations catalyzed by three different catalyst systems were characterized. Our calculations show that the Csp2H?O H-bond interaction between the benzene ring of the catalyst and H2O is mainly responsible for the chiral discrimination observed. The Brønsted acid counterion plays a very important role in ensuring high enantioselectivity by improving the rigidity of the transition state structures to allow the efficient formation of the Csp2H?O H-bond. Moreover, we explain why these two diamine catalysts (1S,2S)-DACH and (1R,2R)-DPEN display consistent enantioselectivities in the catalytic epoxidation of 2-cyclohexen-1-one when combining with three different cocatalysts; achiral TFA, and chiral (R)- and (S)-TRIP. 相似文献
14.
K. Praveen Kumar S. Satyanarayana P. Lakshmi Reddy G. Narasimhulu Narender Ravirala B.V. Subba Reddy 《Tetrahedron letters》2012,53(14):1738-1741
Iodine is found to be a highly efficient catalyst for the three-component coupling (3CC) of aldehydes, β-naphthol, and 1,3-dimethylbarbituric acid under solvent-free conditions to afford the corresponding 8,10-dimethyl-12-aryl-12H-naphtho[1′,2′5,6]pyrano[2,3-d]pyrimidine-9,11-diones in good yields with high selectivity. The use of readily available iodine makes this method very simple, convenient, and cost-effective. 相似文献
15.
Ayyakannu Arumugam Napoleon Fazlur-Rahman Nawaz Khan Euh Duck Jeong Eun Hyuk Chung 《Tetrahedron letters》2014
An efficient, three-component domino reaction of dimedone 1, aromatic aldehydes (2a–o), and 1,3-cyclohexanedione 1a in the regio-selective synthesis of 3,3-dimethyl-9-phenyl-2H-xanthene-1,8(5H,9H)-diones (3a–o) is reported. The desired product, 3 is efficiently promoted by ascorbic acid as an organo catalyst. 相似文献
16.
Farhad Hatamjafari 《Helvetica chimica acta》2013,96(8):1560-1563
Protocols with starch? sulfuric acid (SSA) as reusable catalyst for the synthesis of aryl‐1H‐pyrazoles are described. SSA acted as an efficient and environmentally friendly catalyst for the regioselective condensation of Baylis? Hillman adducts 1 with phenylhydrazine hydrochloride leading to the new 1,5‐diaryl‐1H‐pyrazole 2a – 2e in excellent yields (Scheme and Table 1). 相似文献
17.
Cheng Jiang Qi Dong You Department of Medicinal Chemistry China Pharmaceutical University Nanjing China 《中国化学快报》2007,18(6):647-650
An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives using formic acid as catalyst, from aldehydes,β-ketoester and urea(thiourea) without solvent under the irradiation of microwave is described. Compared with the classical Biginelli reaction, this new method has the advantage of good yields (77-94% for aromatic aldehydes) and short reaction time (3-8 min). 相似文献
18.
Amol Maruti Jadhav Sandip Gangadhar Balwe Jong Su Kim Kwon Taek Lim Yeon Tae Jeong 《Tetrahedron letters》2019,60(7):560-565
An efficient, inexpensive and environmentally friendly synthesis of novel 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives has been developed via one-pot three-component reaction of phthalhydrazide or maleic hydrazide, aldehydes and arylacetonitrile in the presence of catalytic amount of InCl3 as a Lewis acid catalyst under solvent-free conditions. The most important features of the present protocol are mild reaction conditions, short reaction times, high yields, and a wide range of functional group tolerance. 相似文献
19.
Daniel L. da SilvaSergio A. Fernandes Adão A. SabinoÂngelo de Fátima 《Tetrahedron letters》2011,52(48):6328-6330
A new and efficient methodology is proposed for obtaining 3,4-dihydropyrimidin-2(1H)-ones/-thiones through Biginelli reactions. It is based on the use of less than the stoichiometric amount of p-sulfonic acid calixarenes as organocatalysts. A number of aromatic aldehydes as well as urea or thiourea can be employed for successfully synthesizing the corresponding Biginelli adducts. The described methodology is devoid of metal-containing catalysts, which in turn is very attractive for safely producing 3,4-dihydropyrimidin-2-(1H)-ones/-thiones of pharmacological interest. In addition, the catalyst efficiency is not compromised after its successive use in reactions. This is the first report about the application of calixarenes as catalysts in the multicomponent Biginelli reaction. 相似文献
20.
Maryam Moosavifar 《Comptes Rendus Chimie》2012,15(5):444-447
A mild and efficient catalytic method has been developed for the synthesis of 3,4-dihydropyrimidin-2 (1H)-ones (DHPM) by a one-pot three-component cyclocondensation reaction using molybdophosphoric acid (MPA) supported on Y zeolite in high to excellent yields. The reaction investigated in the presence of molybdophosphoric acid encapsulated in the supercage of zeolite for comparison. In the second method, no appreciable progress was observed due to large size of dihydropyrimidinone compounds towards the supercage dimension of Y zeolite. In addition, the catalyst was recovered and reused for several times without efficient loss in catalytic activity. 相似文献