Reaction Of Active Methylene Compounds Research Articles

Water-Soluble Calixarenes as New Inverse Phase-Transfer Catalysts. Their Scope in Aqueous Biphasic Alkylations and Mechanistic Implications

Alkylation reactions of active methylene compounds, alcohols and phenols with alkyl halides in aqueous NaOH solution can be carried out without the need for any added organic solvents in most cases. The water-soluble calix[n]arenes, which contain trimethylammoniomethyl groups on the upper rim, were used as inverse phase-transfer catalysts, resulting in the corresponding alkylated products in good to high yields. The scope of this methodology in aqueous biphasic alkylation reactions and the mechanistic implications are discussed.

A One-Pot Synthesis of Pyrido[2,3-d]- and Quinolino[2,3-d]pyrimidines

The in situ formed methylene derivatives of 1,3-dicarbonyl compounds; ethyl cyanoacetate; malononitrile and ketones; react with 6-amino1,3-dimethyluracil as activated alkenyl derivatives, affording Michael adducts. The adduts simultaneously undergo cyclization to furnish pyrido[2,3-d]or quinolino[2,3-d]pyrimidine derivatives in high yield. Uracil and its annelated substrates occupy a unique place in the field of medicinal chemistry as useful anticancer and antiviral drugs. Besides, the discoveries of many pyrido[2,3-d]pyrimidine derivatives with potential antitumor, anti-inflammatory and CNS depressant activities, have stimulated considerable interest in the synthesis of pyrido[2,3-d]pyrimidines via new and efficient routes. Many strategies have been developed for the preparation of these compounds. One of the major routes involves the reaction of 6-aminouracil with cyanolefins. An alternative route involves the condensation of 6amino-1,3-dimethyluracil-5-carboxaldehyde with active methylene compounds. Herein we wish to disclose a simple straightforward, three-component heteroannulation reaction that converts 6-aminouracil into pyrido[2,3-d]or quinolino[2,3-d]pyrimidines in high yield. The reaction of active methylene compounds with formaldehyde has been reported to afford in situ the corresponding ylidene derivatives and thus can be considered as synthetic equivalent of these intermediates. The reaction of these reactive synthons with heterocyclic enamines has not been reported. 6-Aminouracils have been reported to behave as heterocyclic enamines and undergo Michael addition with different activated olefins and acetylenes, followed by cyclization to afford annelated heterocycles. We have found that a 2: 2: 1 mixture of active methylene compounds (1a-e); formaldehyde and 6-amino-1,3-dimethyluracil (2), reacts in refluxing ethanol containing a catalytic amount of piperidine to give the annelated pyrimidine derivatives (4a-e) in 91-73 % yield. However, bis(6-amino-1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimid-5-yl)methane (5) was detected in a minute amount and was separated easily by fractional crystallization (lit., mp > 300 C). Moreover, the reaction tolerates cyclic active methylene compounds. Thus, the reaction of indane-1,3-dione or dimedone with formaldehyde and 2 affords the indenopyridopyrimidine derivative (6) and quinolinopyrimidine derivative (7) in 69% and 81%yields, respectively.

ChemInform Abstract: Studies on the One‐Pot Reaction of Active Methylene Compounds with 2‐Bromoethanol — Preparation of α‐Oxoketene Cyclic O,S‐Ethylene Acetals.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Synthesis of 3‐Substituted 4‐Hydroxyquinolin‐2‐ones via C‐Acylation Reactions of Active Methylene Compounds with Functionalized 3,1‐Benzoxazin‐4‐ones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and enantiomeric excess measurements of optically active N-acetyl tetramic acids

A facile route to chiral functionalised tetramic acids through C-acylation–cyclisation reactions of active methylene compounds with N-hydroxysuccinimide esters of N-acetyl- l-amino acids is described. Enantiomeric excesses and physical characteristics of all compounds are reported.

Synthesis of 3-Substituted 4-Hydroxyquinolin-2-ones via C-Acylation Reactions of Active Methylene Compounds with Functionalized 3,1-Benzoxazin-4-ones

Synthesis of 3-Substituted 4-Hydroxyquinolin-2-ones via C-Acylation Reactions of Active Methylene Compounds with Functionalized 3,1-Benzoxazin-4-ones

ChemInform Abstract: Synthesis of N‐Alkoxycarbonyl‐3‐substituted Tetramic Acids and Functionalized Enols via C‐Acylation Reactions of Active Methylene Compounds with N‐Hydroxysuccinimide Esters of N‐Alkoxycarbonyl‐α‐amino Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of N-alkoxycarbonyl-3-substituted tetramic acids and functionalized enols via C-acylation reactions of active methylene compounds with N-hydroxysuccinimide esters of N-alkoxycarbonyl-α-amino acids

The N-hydroxysuccinimide esters of N-alkoxycarbonyl-α-amino acids react with active methylene compounds (malonic and acyl acetic esters), under basic conditions, to produce N-alkoxycarbonyl-3-substituted tetramic acids 7–17; in the case of the N-hydroxysuccinimide ester of L-alanine, the corresponding optically active tetramic acids 15 and 16 are obtained. In addition, the C-acylation reactions of cyanoacetic esters furnishes the functionalized enols 18–23 in very good yields. Spectral data and physical characteristics for all compounds are reported.

ChemInform Abstract: Reaction of Active Methylene Compounds with α‐Fluoroalkyl Ketones or Esters: A Convenient Synthesis of 4‐ Trifluoromethylpyridines and meta‐Trifluoromethylphenols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Studies with polyfunctionally substituted heteroaromatics: A facile route for the synthesis of polyfunctionally substituted N-aminopyridines, 1,2,4-triazolo[1,5-a]pyridines and isoquinolines

The reactions of formaldehyde and acetaldehyde with active methylene compounds, followed by reaction with cyanoacetic acid hydrazide 2, afforded N-aminopyridine-2-one derivatives 5a-f. In contrast, the reactions of cyanoacetic acid hydrazide 2 with aliphatic aldehydes and cyanothioacetamide afforded pyridinethione derivatives 11a-b. Also, the reactions of active methylene compounds with formaldehyde and cyanoacetamide afforded pyridin(1H)-2-one derivatives 12a-c. The reactions of 5b with aldehydes and ketones afforded compounds 13a, b, 14, and 15, respectively. The reactions of 5b with arylidinemalononitriles 16a,b afforded isoquinoline derivatives 19a,b. Compound 19b by hydrolysis gave the final product 20. Compound 20 could also be formed by hydrolysis of 5b to give 21, followed by the reaction with 16b. © 1997 John Wiley & Sons, Inc.

Reaction of Active Methylene Compounds with α-Fluoroalkyl Ketones or Esters: A Convenient Synthesis of 4-Trifluoromethylpyridines and meta-Trifluoromethylphenols

The reaction of alpha-fluoroalkyl ketones 1 or ethyl alpha-fluoroalkylacetates 2 with active methylene compounds such as methyl acetoacetate (3), acetylacetone (4) and diethyl malonate (5) produced unsaturated fluoroalkyl-containing 1,5-dicarbonyl compounds 6, from which polyalkyl-substituted 4-trifluoromethylpyridines 7, 4-trifluoromethylpyrid-2(1H)-ones 8 and meta-trifluoromethylphenols 9 were synthesized conveniently.

Michael Reaction of Stabilized Carbon Nucleophiles Catalyzed by [RuH2(PPh3)4

The Michael reaction of active methylene compounds lacking cyano groups such as malonates, β-ketoesters, 1,3-diketones, 1,1-disulfones, nitrocompounds, Meldrum acid, and anthrone with common acceptors proceeds in acetonitrile solution in the presence of [RuH2(PPh3)4] as the catalyst. Cyano acetates, more acidic than malonates in organic solvents, are also excellent substrates for this reaction. In a number of cases, intramolecular aldol reactions catalyzed by [RuH2(PPh3)4] were also observed as side reactions. Catalysis by other ruthenium and rhodium complexes has been examined. Selectivity studies performed with malonate and disulfone donors indicate that the catalyst selectively activates Michael donors that can coordinate with ruthenium(II). Additionally, it has been shown that the reaction requires the presence of free phosphine. Therefore, the Michael reaction of stabilized enolates appears to be a ruthenium- and phosphine-catalyzed reaction. From a practical point of view, the use of readily prepared [RuH2(PPh3)4] as the catalyst in acetonitrile provided the best solution for the Michael reaction of active methylene compounds.

ChemInform Abstract: An Improved and Efficient Method for Diazo Transfer Reaction of Active Methylene Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Studies on Conjugated Nitriles. Part 7. Lewis Acid‐Promoted Reaction of Active Methylene Compounds with Diethyl Phosphorocyanidate; Preparation of α,β‐Unsaturated α‐Aminophosphonates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An Improved and Efficient Method for Diazo Transfer Reaction of Active Methylene Compounds

Abstract Diazo transfer reactions between active methylene compounds and the p-toluenesulfonyl azide can be efficiently mediated in the presence of cesium carbonate.

Studies on Conjugated Nitriles. VII. Lewis Acid-Promoted Reaction of Active Methylene Compounds with Diethyl Phosphorocyanidate; Preparation of .ALPHA.,.BETA.-Unsaturated .ALPHA.-Aminophosphonates.

Reaction of diethyl phosphorocyanidate (DEPC) with dimethyl malonate (1a) and ethyl cyanoacetate (1b) in the presence of zinc chloride and triethylamine resulted in selective addition of 1a, b to the cyano group of DEPC to give α, β-unsaturated α-aminophosphonates (2a, b). In contrast, similar treatment of enolizable methyl acetoacetate (1c) and acetylacetone (1d) with DEPC gave the corresponding enolphosphates (4c, d) as a result of nucleophilic displacement on the phosphorus atom of DEPC. Conversion of the resulting α-aminophosphonate (2a) to uracil-6-phosphonates (6a, b) was achieved by treatment with phenyl isocyanate (5a) and isothiocyanate (5b), respectively.

Synthesis and application of some new furoquinolinediones as bactericides

Furo[3,2-g]quinoline-4,9-diones were prepared through the reaction of active methylene compounds with 6,7-dichloroquinoline-5,8-dione, either by one step or two step method. Benzo[b]- and naphtol[1,2-b or 2,1-b]furo[3,2-g]quinolinediones were also prepared through the reaction of 6,7-dichloroquinoline-5,8-dione with phenols and naphtols in presence of pyridine. The structure of the synthesized compounds was determined by elemental and spectral analysis.

ChemInform Abstract: Synthesis of a New Chiral Phase‐Transfer Catalyst: Chemical Activity in Alkylation Reactions.

AbstractThe catalyst (III), available starting from D‐(+)‐tartaric acid via the known intermediate (I) is found to be more active than the conventional tetraalkylammonium salts in alkylation reactions of active methylene compounds under usual solid‐liquid phase‐transfer conditions.

ChemInform Abstract: Convenient Synthesis of Sulfur Ylides (III) by Reaction of Active Methylene Compounds (II) with the Corey‐Kim Reagent (I).

ChemInform Abstract: Convenient Synthesis of Sulfur Ylides (III) by Reaction of Active Methylene Compounds (II) with the Corey‐Kim Reagent (I).

Diastereoselective 1,4-addition of various nucleophiles to 5-trimethylsilyl-2-cyclohexenone: synthesis of (+)-ramulosin

Base catalyzed reaction of active methylene compounds or oxygen catalyzed reaction of trialkylboranes via radical pathway with 5-trimethylsilyl-2-cyclohexenone (1) gave the corresponding products with modest to high (3:2– 20:1) diastereopurities. High diastereoselectivity (6:1– > 20:1) was observed in the reactions of enol silyl ethers, allylsilanes, hydrogenperoxide, and diethylaluminium cyanide with 1 and its 3-substituted derivatives. Full details of the total synthesis of (+)-ramulosin utilizing the diastereospecific product are also described.