Pyrimidine derivatives 4a-4c was prepared by a Biginelli cyclocondensation of g -ketoesters, aryl aldehydes, and thiourea derivatives under microwave irradiation. A simple and fast synthesis of bicyclic pyrimidine derivatives 6a-6c was performed by microwave-assisted reaction of 4a-4c with bromomalononitrile ( 5 ). Reaction of bicyclic pyrimidines 6a-6c with HCO 2 H and HONH 3 Cl under microwave irradiation gave tricyclic pyrimidines 7a-7c and 8a-8c respectively. 相似文献
The reaction of 4-hydroxycoumarin (1) with some primary amines 2a-h and morpholine (2i) under microwave irradiation occurred without opening of the lactone ring to give N-substituted 4-aminocoumarins 3a-i in excellent yields. Under the same experimental conditions, 4-hydroxy-6-methyl-2-pyrone (4) reacted with benzylamine (2e) or 2-phenyl- ethylamine (2f) to give the corresponding N,N'-disubstituted 4-amino-6-methyl-2-pyridones 5e,f. The main advantages of this procedure are dramatically shortened reaction times, higher amine utilization and considerably improved yields. 相似文献
5-(3-Methyl-2-phthalimidylpentanoylamino)isophthalic acid as a novel aromatic diacid monomer was prepared in three steps. In the first step, phthalic anhydride was reacted with l-isoleucine in acetic acid solution, and the resulting imide acid was obtained in high yield. In the second step, treatment of this imide acid with excess thionyl chloride gave aliphatic acid chloride in good yield. In the last step, this acid chloride was reacted with 5-aminoisophthalic acid to provide novel bulky chiral aromatic diacid monomer. The direct polycondensation reactions of this diacid with several aromatic and aliphatic diisocyanates such as 4,4′-methylenebis(phenyl isocyanate), toluylene-2,4-diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate were carried out under microwave irradiation. In order to compare this method with classical heating, the polymerization reactions were also performed under solution polycondensation conditions. The polymerization reactions occurred rapidly under microwave conditions and produced a series of novel optically active polyamides (PA)s containing pendent phthalimide group, with good yields and moderate inherent viscosities of 0.17-0.60 dL/g. Some of the new PAs showed good solubility and are readily soluble in organic solvents. The resulting macromolecules were characterized by FT-IR, specific rotation, and representative ones by 1H NMR, elemental and thermogravimetric analyses (TGA). 相似文献
New sulfonamide‐β‐lactam molecular conjugates 3 ( a – l ) have been generated through microwave‐assisted synthesis. β‐Lactams 1 ( a – e ) reacted with selected sulfonamides under microwave irradiation in the presence of KI and mediated by K2CO3 to afford conjugates 3 ( a – l ). All new compounds were structurally authenticated by spectroscopic and elemental analyses. 相似文献
Coupling the diazonium salt of 3-amino-2-cyano-4,6-dimethylthieno[2,3-b]pyridine 1 with malononitrile 2 gave 2-cyano-3-(hydrazonomalononitrile)-4,6-dimethylthieno[2,3-b]pyridine 3 which then reacted with hydrazine compounds 4a-4h to yield corresponding 2-cyano-3-(3,5-diamino-1-substituted-pyrazol-4-yl)azo-4,6-dimethylthieno[2,3-b]pyridines 5a-5h. The 2-cyano-3-(2-amino-5,7-disubstituted-pyrazolo-[1,5-a]pyrimidine-3-yl)azo-4,6-dimethylthieno[2,3-b]pyridines 7a-7f were obtained in good yield by the cyclocondensation reaction of 2-cyano-3-(3,5-diamino-pyrazol-4-yl)azo-4,6-dimethylthieno[2,3-b]pyridine 5a with the appropriate 1,3-diketones 6a-6f under acidic condition. 相似文献
Abstract Amidoximes (1) reacted with isopropenyl acetate in presence of KSF under microwave irradiation and gave 1,2,4-oxadiazoles (2). 1,2,4-Oxadiazoles (4) can also be obtained by microwave irradiation from O-acylamidoximes (3) adsorbed on Alumina. 1,3,4-Oxadiazoles (6) were obtained by irradiation of bis (acyl) hydrazines (5) in thionyl chloride. 相似文献
Summary: Investigations regarding the cationic ring‐opening polymerization of 2‐phenyl‐2‐oxazoline under microwave irradiation and conventional heating are reported. This study was inspired by contradictory reports of the (non‐)existence of non‐thermal microwave effects that might accelerate the cationic ring‐opening of 2‐oxazolines. The polymerization of 2‐phenyl‐2‐oxazoline was investigated under pressure in acetonitrile and under reflux (or at the boiling point of butyronitrile in a closed vessel) in butyronitrile utilizing a single‐mode microwave reactor and automated synthesis robots with conventional heating.
A fatty epoxide (tetradecyl-oxirane) is reacted with diethyl acetamidomalonate in basic medium, with or without solvent under solid-liquid phase transfer catalysis with LiCl, or under microwave irradiation on supported reagents (KF/Al2O3/LiCl). The main product is a lactone which is formed after epoxide ring opening and subsequent cyclisation. We put here into evidence, for the first time, the conjugated advantages of “dry media” reactions, lithium salt effects and microwave irradiation. 相似文献
A resin capture and release strategy for making a combinatorial array of 2,4,5-trisubstituted pyrimidines is demonstrated by capturing beta-ketoesters and beta-ketoamides on a solid-supported piperazine. Through a cyclocondensation reaction, the solid-supported enaminone is reacted with several guanidines under heating or microwave irradiation affording the corresponding pyrimidines in good yield and chemical purity directly on solution. After this final step, the support can be effectively recycled. 相似文献
The synthesis of 4-(-2-hydroxybenzoyl)pyrazoles (3) was achieved in a single step by the reaction of 3-formylchromones (1) with Phenylhydrazine or Tosylhydrazine under microwave irradiation without a solvent. 相似文献
Enaminone 1 was reacted with hydrazonoyl halides 2a-d to yield 3,4-disubstituted pyrazoles 6a-d. Coupling with arenediazonium chlorides afforded the 2-(arylhydrazono)-3-(1-naphthalenyl)-3-oxopropionaldehydes 13a-c. Compounds 13 could be utilized for the synthesis of a variety of arylpyrazoles, arylazolopyrimidines, and pyridazinones via reaction with hydrazines, aminoazoles, and active methylene derivatives, respectively. A comparative study of aforementioned reactions was carried out with chitosan as a basic ecofriendly catalyst under conventional heating as well as under pressurized microwave irradiation conditions. 相似文献
Exposure of alcohols 2a-2j to 2-silyl-butadienes in the presence of ruthenium complexes modified by (R)-SEGPHOS or (R)-DM-SEGPHOS results in redox-triggered generation of allylruthenium-aldehyde pairs, which combine to form products of carbonyl crotylation 4a-4j in the absence of stoichiometric byproducts and with high levels of syn-diastereo- and enantioselectivity. In the presence of isopropanol under otherwise identical conditions, aldehydes 3a-3j are converted to an equivalent set of adducts 4a-4j. Whereas reactions conducted using conventional heating require 48 h, microwave irradiation enables full conversion in only 4 h. Finally, as illustrated in the conversion of adduct 4a to compounds 6a and 6b, diastereoselective hydroboration-Suzuki cross-coupling with aryl and vinyl halides followed by Fleming-Tamao oxidation enables generation of anti,syn-stereotriads found in numerous polyketide natural products. 相似文献