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1.
《合成通讯》2013,43(13):2009-2015
ABSTRACT The unsymmetrical Knoevenagel–Michael product derived from Meldrum's acid, phenyl Meldrum's acid and formaldehyde was prepared as a pure, stable and crystalline product. This compound readily dissociates under the reaction conditions to produce methylene Meldrum's acid. This Knoevenagel–Michael product was used to explore a new application of methylene Meldrum's acid: the reaction with enamines. 相似文献
2.
Yasuo Morita Masakazu Kaneko Sumiko Matsuzawa Yutaka Yamamoto 《Journal of heterocyclic chemistry》1997,34(2):515-519
Facile and convenient methods for the preparation of a variety of 2,6-disubstituted 4H-1,3-oxazin-4-ones 3 by three complementary methods are described. Treatment of the branched aliphatic imidate 2c,d with diketene 1 in the presence of a catalytic amount of acetic acid affords 2-substituted 6-methyl-1,3-oxazin-4-ones 3c,d , whereas the unbranched imidate 2b,e gave oxazines 3b,e and pyrimidines 4b,e (Method A). The reaction of acyl Meldrum's acid 5 with imidate 2 afford 2,6-disubstituted oxazine 3, though the alkylimidate with acetyl Meldrum's acid yielded 3 and 5-acetyl-1,3-oxazine-4,6-dione 8 (Method B). The cylodehydration of acylacetylcarboxamide 13 with acid, such as 70% perchloric acid or fluorosulfonic acid, afforded 1,3-oxazines 3 (Method C). 相似文献
3.
Jairo Quiroga Angelina Hormaza Braulio Insuasty Claudio Saitz Alvaro Caete Carolina Jullian 《Journal of heterocyclic chemistry》1998,35(1):61-64
A series of pyrazolo[1,5-a]pyrimidin-3-ones 3 was prepared from Meldrum's acid and 5-amino-3-arylpyrazoles 1 by cyclization in nitrobenzene of the corresponding 5-pyrazolylaminomethylene Meldrum's acid derivatives 2 . The structure of pyrazolo[1,5-a]pyrimidin-3-ones and their precursors were determined by nmr measurements. 相似文献
4.
Abolfazl Heydari Maryam Hosseini Mahdieh Darroudi Masoumeh Behzadi Viktor Hronský Gabriel Sučik Hossein Rouh Hassan Sheibani 《先进技术聚合物》2023,34(2):587-596
In this study, polystyrene was functionalized with Meldrum's acid toward the introduction of the ketenes (CCO) system to its backbone for producing a dramatically reactive intermediate. Meldrum's acid, as a ketene source, was reacted by poly(styrene-co-p-chloromethyl styrene) through a simple nucleophilic reaction to synthesize poly(styrene-co-styryl Meldrum's acid). Then, the pendant Meldrum's acid under thermal treatment converted to ketene intermediate resulting in highly reactive polystyrenes derivatives, which rapidly reacted by nucleophilic reagents to afford ultimate organic building blocks. The polystyrene derivatives were characterized using elemental analysis, FT-IR, high-resolution solid-state NMR, thermogravimetric analysis (TGA), and differential thermogravimetric analysis (DTG). To clarify the evolutionary mechanisms of polystyrene products, density functional theory (DFT) method B3LYP with the 6–311++G(2d,p) basis set was used. We studied the preparation of polystyrene model compounds through Meldrum's acid thermolysis and nucleophilic substitution. The kinetic and thermodynamic parameters in all reactions and the structural and electronic properties of all molecules were calculated. These data exhibited that based on Gibbs Free energy values, the structure of syndiotactic polystyrene is more stable than that of isotactic polystyrene. Furthermore, it was found that the presence of an electron donor or acceptor substituent on the polystyrene structure affects the electronic bandgap. 相似文献
5.
Reaction of aryl aldehydes with Meldrum's acid 2 in the presence of formic acid and triethylamine gives 5-arylmethyl Meldrum's acid derivatives 4 at room temperature, whereas at 80–100°C 3-arylpropanoic acids 5 are formed. 相似文献
6.
We were in need of several aliphatic monoalkylidene derivatives of Meldrum's acid (1) for use in conjunction with a current synthetic problem. Implementation of base1,2 or Lewis acid3 initiated Knoevenagel conditions were found to be unsatisfactory, in our hands, due to the intercedence of subsequent Michael addition of Meldrum's acid to the desired product. We reasoned, therefore, that a method should be employed which generates the alkylidene derivative in the absence of Meldrum's acid. 相似文献
7.
Sandrine Roche Saïd Yous Daniel Couturier Benoît Rigo 《Journal of heterocyclic chemistry》1999,36(4):1073-1075
The reaction of Meldrum's acid with silylated anilines substituted by an electron withdrawing group easily yields the corresponding N-phenyl malonamic acid, when the reaction is performed under high vacuum in dichlorobenzene. 相似文献
8.
N. Arnau J. Corts M. Moreno-Maas R. Pleixats M. Villarroya 《Journal of heterocyclic chemistry》1997,34(1):233-239
Palladium(0)-catalyzed allylation of imidazoles, 6-methyluracil, 2-pyrimidinone, and Meldrum's acid with cyclopentadiene monoepoxide and cis-cyclopentene-3,5-diol mono and dicarbonate is described. 相似文献
9.
Meldrum's acid (1) on bisacylation with succinyl chloride afforded a neutral diketo product (2); however, the dimer enolic products (3) with acidic nature resulted in glutaryl and adipyl dichlorides. Monoacylation of (1) with acetyl chloride gave acidic 5‐acetyl Meldrum's acid (4) in enol form. 相似文献
10.
Dominique Fasseur Benoît Rigo Catherine Leduc Pascal Cauliez Daniel Couturier 《Journal of heterocyclic chemistry》1992,29(5):1285-1291
The condensation of iminoether 7 , derived from pyroglutamic acid (4) , with active methylene reagents such as Meldrum's acid or methyl cyanoacetate, lead to β-enaminoesters 2 . Solid-liquid phase transfer N-alkylation of these compounds is described. 相似文献
11.
Sergey V. Ryabukhin Andrey S. Plaskon Dmitriy M. Volochnyuk Sergey E. Pipko Andrey A. Tolmachev 《合成通讯》2013,43(17):3032-3043
A facile one-pot method for the synthesis of 1,2,3,4-tetrahydroquinoline-3-carboxylic acids and their heterocyclic analogs based on the tert-amino effect. A set of 1,2,3,4-tetrahydroquinoline-3-carboxylic acids was readily prepared starting from various ortho-dialkylaminoaldehydes and Meldrum's acid using Me3SiCl in dimethylformamide (DMF) solution. 相似文献
12.
Stylianos Hamilakis Demetrios Kontonassios Constantine Sandris 《Journal of heterocyclic chemistry》1994,31(5):1145-1150
The C-acylation reactions of the active methylene compounds, methyl cyanoacetate and Meldrum's acid, with hippuric acid, using the DCC activation and the mixed anhydride conditions, are shown to proceed through initial formation of 2-phenyl-5(4H)-oxazolone, the hippuric acid azlactone. The conditions of these reactions using the azlactone as the acylating agent were investigated and discussed. 相似文献
13.
New tetrahydro‐1H‐1,5‐benzodiazepin‐2‐phenylacetamides were synthesized in good yields by a four‐component reaction of benzylidene Meldrum's acid, benzene‐1,2‐diamines, isocyanides, and water in CH2Cl2 at room temperature. 相似文献
14.
Bismethylthiomethylene Meldrum's acid reacts with amides in the presence of potassium hydroxide to afford methylthioacylaminomethylene Meldrum's acid 5. Aminolysis of 5 gives aminoacylaminomethylene Meldrum's acids 7. Thermolysis of 5 and 7 supplies a novel synthetic method of 4-methylthio- and 4-amino-2-aryl-6H-1,3-oxazin-6-ones. 相似文献
15.
A series of new indeno[2,1‐f]quinolin‐3(2H)‐one derivatives were synthesized by a reaction of aromatic aldehyde with Meldrum's acid (2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione) and 9H‐fluoren‐2‐amine under microwave irradiation without catalyst in glacial acetic acid. This reaction has notable advantages of short reaction time, high yield and convenient operation. 相似文献
16.
Rufine Aku‐Gdu Hayate El‐Hafidi Benoît Rigo Daniel Couturier 《Journal of heterocyclic chemistry》2006,43(2):365-369
17.
Novel spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] derivatives were prepared by the three‐component reaction of isatins 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine and Meldrum's acid in the presence of a catalytic amount of melamine trisulfonic acid. This protocol provides a simple one‐step procedure with the advantages of easy work‐up, mild reaction conditions and environmentally benign. 相似文献
18.
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
19.
An efficient chemoselective synthesis of 4‐aryl‐2,3‐dihydropyrimido[1,2‐a]benzimidazol‐2‐one derivatives from three‐component reactions of 2‐aminobenzimidazole, Meldrum's acid, and aldehydes via [3+3] atom combination is described. The reaction occurs in different conditions such as in DMF as solvent at reflux and in the presence of l ‐proline as base catalyst. 相似文献
20.
Reaction of o-methoxybenzaldehydes with Meldrum's acid followed by cyclization in sulfuric acid of the benzylidene derivatives 3a-g affords 3-carboxycoumarins in excellent yields. 相似文献