Synthesis of diethyl 6-aryl-2-oxo-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates

Reaction of diethyl oxalylacetate sodium salt with aromatic aldehydes and urea led to the formation of diethyl 6-aryl-2-oxo-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates.     

1-(2-氨基-3,5-二氰基-4-芳基-4H-吡喃-6-基)愈创兰烃薁的合成

在醋酸铵作用下,通过1-氰乙酰基愈创兰烃薁、芳香醛、丙二腈的三组分反应,一锅法合成了一系列1-(2-氨基-3,5-二氰基-4-芳基-4H-吡喃-6-基)愈创兰烃薁衍生物.该反应操作简单、条件温和、收率良好.产物结构经NMR,MS,IR及元素分析等得以证实.     

Synthesis and properties of 1-substituted derivatives of diethyl 4-aryl-1,4-dihydrcpyridine-3,5-dicarboxylic acid esters

1-Unsubstituted 4-aryl-3,5-diethoxycarbonyl-1,4-dihydropyridines in the presence of NaH form anions that react with alkyl halides, acid chlorides, and halo acid esters to form the corresponding 1-substituted derivatives of 1,4-dihydropyridine Hydrolysis of one or both ethoxycarbonyl groups in the 3 and 5 positions, as well as hydrolysis of ethyl 4-phenyl-3,5-diethoxycarbonyl-1,4-dihydropyridinyl-1-acetate, occur upon reaction with alkali, but 1,3,5-triethoxycarbonyl-4-phenyl-l,4-dihydropyridine gives the corresponding unsubstituted 1,4-dihydropyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1067–1071, August, 1982.     

1,4-二氢-4-芳基-3,5-吡啶二羧酸酯的合成及表征

基于二氢吡啶化合物的构效关系, 设计了一系列1,4-二氢-4-芳基-3,5-吡啶二羧酸酯新化合物. 含有易于水解基团的1,4-二氢-4-芳基-3,5-吡啶二羧酸酯类化合物在碱性条件下水解合成了重要中间体1,4-二氢-4-芳基-3,5-吡啶二羧酸单酯, 收率93%～99.8%. 该二羧酸单酯与α-溴代芳基乙酮在相转移剂催化下反应合成目标化合物, 收率74%～99%. 中间体和目标化合物经¹H NMR, ¹³C NMR, IR, MS和元素分析等确证.     

Dehydrohalogenation of substituted diethyl halocyclopropane-1,1-dicarboxylates

The synthesis and dehydrohalogenation of diethyl halocyclopropane-1,1-dicarboxylates prepared from diethyl ethylidene- and benzylidenemalonates are described.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 12, 2004, pp. 1811–1814.Original Russian Text Copyright © 2004 by Boitsov, Kostikov, Molchanov, Stepakov, Baird.     

Practical selective monohydrolysis of bulky symmetric diesters

The highly efficient selective monohydrolysis reaction we previously reported has been applied to monohydrolysis of several bulkyl symmetric diesters, including diethyl esters, dipropyl esters, and dibutyl esters. A greater proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH appear to help improve the reactivity of bulky diesters compared to the corresponding dimethyl esters. The procedure is mild and practical, yielding the corresponding half-esters in high yields under simple conditions.     

Reaction of dialkyl 2-aryl-4-hydroxy-4-methyl-6-oxocyclohexane-1,3-dicarboxylates with aliphatic amines

Benzylamine, phenethylamine, and homoveratrylamine reacted with dialkyl 2-aryl-4-hydroxy-4-methyl-6-oxocyclohexane-1,3-dicarboxylates at the endocyclic carbonyl group with conservation of the enolic hydroxy group to give dialkyl 4-alkylamino-2-aryl-6-hydroxy-6-methylcyclohex-3-ene-1,3-dicarboxylates. The reaction of dimethyl 4-hydroxy-4-methyl-6-oxo-2-phenylcyclohexane-1,3-dicarboxylate with tryptamine was accompanied by dehydration with formation of dimethyl 4-[2-(1H-indol-3-yl)ethylamino]-6-methyl-2-phenylcyclohexa-3,5-diene-1,3-dicarboxylate, presumably due to basic properties of the indole nitrogen atom.     

Synthesis of 4,6-Disubstituted Dimethyl Pyridazine-3,5-dicarboxylates

Dimethyl pyridazine-3,5-dicarboxylates were synthesized by reaction of substituted 2-cyclo-propenecarboxylates with methyl diazoacetate, followed by oxidation of the resulting 1,4-dihydropyridazine-4,6-dicarboxylates.     

Bromination of 4-aryl-3,5-dialkoxycarbonyl-2,6-dimethyl-1,4-dihydropyridines

4-Aryl-3,5-dialkoxycarbonyl-2,6-dimethyl-1,4-dihydropyridines are brominated by N-bromosuccinimide in methanol at room temperature at the methyl groups at positions 2 and 6 to form mono-, di-, tri-, and tetrabromo derivatives. When the N-unsubstituted bromomethyl-1,4-dihydropyridines are heated they are easily converted to tetrahydrofuropyridines, but in the case of the analogous N-substituted-1,4-dihydropyridines cyclization does not occur. The 2,6-bis(bromomethyl)-substituted products easily replace bromine under the influence of nucleophilic reagents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1230–1235, September, 1991.     

Highly efficient selective monohydrolysis of dialkyl malonates and their derivatives

The highly efficient selective monohydrolysis of symmetric diesters has been applied to monohydrolysis of several dialkyl malonates and their derivatives. The best conditions apply 0.8-1.2 equiv of aqueous KOH with a co-solvent, THF or acetonitrile, at 0 °C. The procedure is highly practical, yielding the corresponding half-esters in high yields in a straightforward manner, without inducing decarboxylation. It was found that the selectivity tends to become higher with increased hydrophobicity.     

Reactions of dimethyl and di-tert-butyl 2-aryl-4-hydroxy-4-methyl-6-oxocyclohexane-1,3-dicarboxylates with difunctional nucleophiles

The nature of the alkyl group in the ester moieties of dimethyl and di-tert-butyl 2-aryl-4-hydroxy-4-methyl-6-oxocyclohexane-1,3-dicarboxylates affects the direction of their reactions with difunctional nucleophiles. The dimethyl esters react with hydrazine hydrate to give the corresponding tetrahydroindazoles, while their tert-butyl analogs are converted under similar conditions into 6-hydrazones. Reactions of both dimethyl and di-tert-butyl 6-oxocyclohexane-1,3-dicarboxylates with hydroxylamine lead to formation of 6-hydroxyimino derivatives.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1687–1691.Original Russian Text Copyright © 2004 by V. Gein, N. Gein, Potemkin, Krivenko.This revised version was published online in April 2005 with a corrected cover date.     

2,3-二氢-3,5-二羟基-6-甲基-4(H)吡喃-4-酮的合成及热裂解行为

以葡萄糖和哌啶为原料，合成、分离并鉴定了2，3－二氢－3，5－二羟基－6－甲基－4－（H）吡喃－4－酮（1），以空气氛下直接热裂解，SPME吸附热裂解挥发生产物的方式，分析鉴定了20个裂解的挥发性化合物，讨论了热裂解的可能过程。