Directions of reactions of 6-amino-, -acetylamino-, and -benzoylaminodeoxyvasicinones with aldehydes

6-Acetylamino- and -benzoylamino-9-arylidenedeoxyvasicinones were synthesized by reaction of 6-amino(3), -acetylamino- (4), and -benzoylamino- (5) -deoxyvasicinones (DOV) with aromatic aldehydes and furfurol in glacial acetic acid. It was shown that the amino group of 6-aminodeoxyvasicinone underwent acylation upon reaction with aldehydes to form 6-acetylamino-DOV, which reacted with aldehydes to form 9-arylidene derivatives. Carrying out this condensation in toluene, o-xylene, and ethanol produced a mixture of condensation products at the 6-amino-and a-CH₂-groups. It was found that condensati on of 3 with 4-nitrobenzaldehyde in pyridine formed exclusively the Schiff bases. Methods for preparing 6-nitrodeoxyvasicinone and for its reduction were improved.     

Synthesen von Heterocyclen, 80. Mitt.: Über ein durch H-Brücken stabilisiertes 2,5-Dihydropyrazin

Zusammenfassung 3-Amino-4-hydroxycumarin (4), welches durch katalyt. Reduktion von 3-Phenylazo-4-hydroxycumarin (1) in 92proz. Ausb. zugänglich ist, wird beim Erhitzen mit 2n-NaOH in 3,6-Bis-(2-hydroxyphenyl)-2,5-dihydropyrazin (10) übergeführt. Die Dehydrierung von10 mit Pd liefert das entsprechende Pyrazin14, das auch aus dem o-Hydroxyphenylglyoxal-phenylhydrazon (13) gewonnen werden kann. Die Reduktion von10 mit Na/Butanol führt zum Piperazin18, die Reaktion mit Ac₂O zum 1,4-Dihydropyrazinderivat17.

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3-Amino-4-hydroxycoumarin (4), obtained in 92% yield by the catalytic hydrogenation of 3-phenylazo-4-hydroxycoumarin (1), is readily converted by refluxing in 2N-NaOH to 3,6-bis-(2-hydroxyphenyl)-2.5-dihydropyrazine (10). The dehydrogenation of10 with a Pd catalyst yields the corresponding pyrazine14, which can also be obtained from the o-hydroxyphenylglyoxal-phenylhydrazone (13). The reduction of10 with sodium in butanol yields the known 2.5-bis(2-hydroxyphenyl)-piperazine (18); the reaction of10 with acetic anhydride leads by isomerization to the 1,4-diacetyl-3,6-bis(2-acetoxyphenyl)-1.4-dihydropyrazine (17).

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Mit 1 Abbildung     

Titanium-dioxide-mediated photocatalysed reaction of selected organic systems

The photocatalysed reaction of four selected organic systems, namely dichlone (1), 2-amino-5-chloropyridine (2), benzoyl peroxide (3) and 3-chloro perbenzoic acid (4), has been investigated in an acetonitrile/water mixture in the presence of titanium dioxide and oxygen. An attempt has been made to identify the products formed during the photo-oxidation process using the GC/MS analysis technique. The photolysis of dichlone (1) leads to the formation of phthalic anhydride (11) and 1H-indene-1,2,3-trione (10), whereas 2-amino-5-chloropyridine (2) gave rise to 2,2′-diamino bipyridyl (14), 2-pyridinamine (16), 2-hydroxy-5-chloropyridine (18), bipyridyl (19) and 2-amino bipyridyl (21). The photolysis of benzoyl peroxide (3) yielded a mixture of products such as benzoic acid (24), biphenyl (27), biphenyl-4-carboxylic acid (29) and benzoic acid phenyl ester (30). Two intermediate products, as 3-chlorobenzaldehyde (35) and hydroxyl added 3-chlorobenzaldehyde (33), have been identified in the case of 3-chloro perbenzoic acid (4). The products have been identified by comparing the molecular ion and mass fragmentation peaks of the products with those reported in the GC-MS library. A probable mechanism for the formation of the products has been proposed.     

NOVEL THREE COMPONENT SYNTHESIS OF 1,2,4-TRIAZOLO[3,4-b]THIAZOLES AND THEIR ANTIMICROBIAL ACTIVITY

1,2,4-Triazolo[3,4-b]thiazole derivatives 5a–j have been synthesized by novel multi-component reaction of 2,4-dichloro-5-fluorophenacyl bromide (1), thiosemicarbazide (2), and aromatic carboxylic acids (4) using phosphorous oxychloride as the cyclizing agent. This reaction protocol is simple, efficient, and requires shorter reaction times in comparison to the conventional multi-step synthesis. The products were identified to be same by an alternate synthesis. All the compounds were screened for their antimicrobial activity against some of bacterial and fungal strains.     

A convergent paired electrochemical synthesis of new heterocyclic compounds. Reaction of benzoquinones with 3-Amino-4-hydroxycoumarin

Electrochemical oxidation of catechols (1) has been studied in the presence of cathodically generated 3-amino-4-hydroxycoumarin (3a) as a nucleophile in aqueous solutions, using cyclic voltammetry and controlled-potential coulometry. The results indicate that the o-benzoquinones derived from catechols (1) participate in Michael addition reaction with 3-amino-4-hydroxycoumarin (3a) to form the corresponding new heterocyclic compounds (7) (oxidized form of coumestan derivatives). The electrochemical process consists of a multi-step including (a) cathodic reduction of 4-hydroxy-3-nitrocoumarin (3) to 3-amino-4-hydroxycoumarin (3a), (b) anodic oxidation of catechols (1) to related o-benzoquinone (2), (c) the Michael addition reaction of 3-amino-4-hydroxycoumarin (3a) to o-benzoquinone (2), and (d) anodic oxidation of formed adduct. The paired electrochemical synthesis of compounds 7a and 7b has been successfully performed in a one-pot process at carbon rods as working and counter electrodes in an undivided cell.     

Water mediated efficient one-pot synthesis of bis-(4-hydroxycoumarin)methanes

Abstract

Manganous chloride (MnCl₂·4H₂O) has been used as an efficient catalyst for an improved and rapid one-pot synthesis of bis-(4-hydroxycoumarin)methanes in excellent yields using water as a reaction medium. This aqueous mediated reaction of various aromatic and heteroaromatic aldehydes with 4-hydroxycoumarin using catalytic amounts of manganous chloride avoids the use of expensive, corrosive reagents, toxic solvents, and provides operational simplicity.     

Versatility of Alternative Reaction Media: Water-Mediated Domino and Green Chemical Synthesis of Pyrimido[1,2-a]benzimidazole Under Nonconventional Conditions

A convenient and clean water-mediated synthesis of a series of 4-amino-2-aryl-1,2-dihydro pyrimido[1,2-a]benzimidazoles (4) is reported using alternative nonconventional energy sources. The products are obtained in shorter times with excellent yields (78–89%) from the multicomponent reaction of 2-aminobenzimidazole (1), malononitrile/ethylcyanoacetate (2a/b), and carbonyl compounds (3). The reaction is found to be general with respect to the cyclic and acyclic carbonyl compounds. The procedure does not involve the use of any additional reagent/catalyst, produces no waste, and represents a green synthetic protocol with high atom economy.     

REACTION OF AROMATIC NITRO COMPOUNDS WITH ELEMENTAL SULFUR IN LIQUID AMMONIA AND AMINES

Abstract

Aromatic nitro compounds were reduced with elemental sulfur in liquid ammonia and in amines, yielding the corresponding anilines. However, introduction of a substituent on the benzene ring or variation of the amine changed somewhat the pattern of this reaction. For example, 4-nitrotoluene (3) and 4-cyanonitrobenzene (6) were found to give not only the corresponding reduced products but also 4,4′-dicyanodiphenyl disulfide (10), formed by replacement of the nitro group, in addition to 4-cyanoaniline (9) in the reaction with elemental sulfur in liquid ammonia. Probable mechanisms of these reactions are discussed in the light of new knowledge on the similar reactions of elemental sulfur.     

Synthesis of Functionalized Dihydrofurocoumarin Derivatives from 3-Aminoalkyl-4-hydroxycoumarin

Some dihydrofuro-fused coumarin derivatives were synthesized from 3-aminoalkyl-4-hydroxycoumarin via in situ generation of N-ylide. The 3-aminoalkylated 4-hydroxycoumarin derivatives were synthesized from one-pot, three-component reaction of 4-hydroxycoumarin, aryl aldehydes, and secondary amines in ethanol at room temperature. Again, when salicylaldehyde was employed instead of benzaldehyde, interestingly pyranocoumarins were obtained. The reaction protocol can be further explored toward the synthesis of many other heterocyclic fused dihydrofurans.     

KF/Al2O3催化下2-氨基-4-芳基-4H-吡喃并[3,2-c]香豆素衍生物的一步合成

以芳醛、4-羟基香豆素和丙二腈或氰乙酸酯为原料, 在KF/Al₂O₃催化下以乙醇为溶剂, 在80 ℃合成了一系列2-氨基-4-芳基-4H-吡喃并[3,2-c]香豆素衍生物, 并通过IR, ¹H NMR和元素分析确证产物的结构.     

Efficient atom-economic one-pot multicomponent synthesis of benzylpyrazolyl coumarins and novel pyrano[2,3-c]pyrazoles catalysed by 2-aminoethanesulfonic acid (taurine) as a bio-organic catalyst

The present work describes eco-friendly multicomponent protocol for the synthesis in excellent yields of structurally diverse benzylpyrazolyl coumarin 5 (a–s) involving the reaction of 4-hydroxycoumarin, ethyl acetoacetate, hydrazine hydrate/phenyl hydrazine hydrate and aldehydes, also novel pyrano[2,3-c]pyrazole derivatives 8 (a–k) integrated by isonicotinic acid hydrazide from reaction of aldehyde, ethyl acetoacetate, malononitrile with isoniazid, employing water as a reaction medium and 2-aminoethanesulfonic acid (taurine) as the catalyst. This new methodology endowed the advantages such as short reaction time, recovery of catalysts after catalytic reaction and reusing them without losing their activity and alleviate of operation.     

Synthesis of Some New 1,3,2-Oxazaphosphinine, 1,3,2-Diazaphosphinine,Acyclic, and/or Cyclic α-Aminophosphonate Derivatives Containing the Chromone Moiety

The synthesis of some new 1,3,2-oxazaphosphinine 18, 1,3,2-diazaphosphinine 19, acyclic, and cyclic α-aminophosphonate derivatives 3–17 containing the chromone moiety have been achieved via reaction of 3-(phenyliminomethyl)chromone (1), 3-(phenylaminomethylene)-2-hydroxychromanone (4), and/or 3-(phenylamino-methylene)-2-(phenylamino)chromanone (5) with diethyl phosphite, tris(2-chloroethyl)phosphite, and phenylphosphonic dichloride. Structures of the products were verified on the basis of their elemental analyses, IR, ¹H, and ³¹P NMR spectral data.     

Efficient Synthesis of Fully Substituted and Diversely Functionalized Pyrazoles through p-TSA Catalyzed One-Pot Condensation of Cyclic β-Diketones,Arylglyoxals and Arylhydrazones

A one-pot, three-component, and atom economic synthesis of biologically and pharmaceutically important fully substituted and functionalized pyrazole derivatives has been accomplished under metal-catalyst-free benign conditions. The strategy involves early condensation of readily available cyclic β-diketones (dimidone, 4-hydroxycoumarin and 2-hydroxy-1,4-naphthoquinone) and arylglyoxals to generate a chalcone type intermediate which upon acid catalyzed condensation with ambident nucleophile arylhydrazones produces various aryl and cyclic β-diketone substituted pyrazole derivatives. The synthesis embraces high functional group tolerance, broad substrate scope, excellent yield of the products, short reaction time and operationally simple and mild reaction conditions. The synthesis provides an easy opportunity of incorporating biologically important N-diarylsulfide/selenide functionality, various enolisable cyclic β-diketones and other bioactive heterocycles concurrently to pyrazole, which may help in designing and development of pyrazole derivatives of pharmacological significance.     

Synthesis of new 4-aroyl-pyrano[c]chromenes via a one-pot,three-component reaction based on aryl glyoxals

A new library of pyrano[c]chromenes containing an aroyl group has been synthesized by a novel multicomponent process involving the reaction of various aryl glyoxals with 4-hydroxycoumarin and malononitrile. The reactions were catalyzed efficiently by ammonium dihydrogen phosphate to yield the desired products in good to excellent yields.     

Synthesis and Reactions of Some New Thieno[2,3-C]pyridazine Derivatives

The alkylation of 4-cyano-5,6-dimethylpyridazin-3(2H)-thione 3 with some halo compounds gave the S-alkylated products 4a–c , which upon treatment with ethanolic sodium ethoxide afforded the cyclized thienopyridazines 5a–c as products. Pyridazothienotriazines 6a–c were prepared by the treatment of compounds 5a–c with nitrous acid, while their reaction with triethyl orthoformate and with carbon disulfide gave the corresponding pyrimidothienopyridazines 7a–c , and 8a–c , respectively. S-alkylated products 9a–o were obtained by the reaction of 8a–c with some halo compounds.     

Über Reaktionen von Nitrosophenolen, 2. Mitt.: Reaktion von 1-Nitroso-2-naphthol mit Orein

Zusammenfassung In der vorliegenden Arbeit wurde die Reaktion von 1-Nitroso-2-naphthol mit Orcin in Äther bei Anwesenheit von HNO₃ studiert. Als Reaktionshauptprodukte wurden 11-Methylbenzo[a]-phenoxazon-(9) (1) sowie dessen 12-Oxid (2) isoliert. Der Reaktionsmechanismus und die Konstitution der erhaltenen Substanzen werden diskutiert. Ferner wurden auch 11-Methyl-5-hydroxy-benzo[a]phenoxazon-(9) (6), 11-Methyl-5-äthoxybenzo[a]phenoxazon-(9), 11-Methyl-5-methoxybenzo[a]phenoxazon-(9) (4), 11-Methyl-5-aminobenzo[a]phenoxazon-(9) (7) und 11-Methyl-5-anilinobenzo[a]phenoxazon-(9) (8) dargestellt.

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In this paper the reaction of 1-nitroso-2-naphthol with orcin in an ether medium in presence of HNO₃ is described. As main products 11-methylbenzo[a]phenoxazone-(9) (1) as well as its 12-oxide (2) were isolated. The reaction mechanism is presented. Identity of the reaction products is verified. 11-methyl-5-hydroxybenzo[a]phenoxazone-(9) (5), 11-methyl-5-methoxybenzo[a]phenoxazone-(9) (4), 11-methyl-5-aminobenzo[a]phenoxazone-(9) (7) and 11-methyl-5-anilinobenzo[a]phenoxazone-(9) (8) are prepared.

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Mit 2 Abbildungen     

Reaction of 2-Thioxo-4-Thiazolidinones Toward Lawesson's Reagent,Phosphorus Pentasulfide,Dialkylaminophosphines, and Phosphorus Ylides

Abstract

2-Thioxo—3-allyl-4-thiazolidinone 1a reacts with Lawesson's reagent (LR, 2) to give the ethylenic product 5 through a coupling reaction along with the dithioxo compound 6. Coupling reaction products of types 8 and 9 are also produced upon reacting thiazolidinones 1 and with the appropriate tris(diallkylamino) phosphine reagent (3 a,b). Reaction of the thiazolidinone 1a with the ylidenetriphenylphosphorane reagents 4 a–c proceeds according to the Wittig mechanism yielding ethylenes 10a–c, respectively. Structural elucidations for the new products were based upon compatible analytical and spectroscopic measurements as well a confirmatory single crystal X-ray structure for 5.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file.     

PREPARATION AND MULTINUCLEAR NMR STUDY OF BENZOYL METHYLENE TRIPHENYLPHOSPHORNE AND BENZOYL METHYLENE TRI-N-BUTYLPHOSPHORANE PT (0) AND PD (0) COMPLEXES

The reactions of Pd (dba)₂ (dibenzylidene acetone palladium (0)) and Pt (dba)₂ (dibenzylidene acetone platinum (0)) with BPPY (Benzoyl Methylene Triphenylphosphorane) and BBuPY (Benzoyl MethyleneTri-n-butylphosphorane) in (1:2) ratios using tetrahydrofuran as solvent have yielded Pd (dba)(BPPY)₂ (1), [Pd (dba)(C(H)COPh(PPh₂-o-C₆H₄)][PPh₃CH₂COPh](2), Pd (dba)(BBuPY)₂ (3), and Pt (dba)(BPPY)₂ (4) complexes. Upon heating complex (1) in THF, a cyclization reaction occurred to give complex (2). The products (1), (2), (3), and (4) are studied by IR, ¹H, ³¹P, and ¹³C NMR technique.     

Task-Specific Ionic Liquid as the Recyclable Catalyst for the Rapid and Green Synthesis of Dihydropyrano[3,2-c]chromene Derivatives

Abstract

A task-specific ionic liquid, [H₃N⁺–CH₂–CH₂–OH][CH₃COO^?], was successfully applied as an efficient and reusable catalyst for the one-pot domino to approach to dihydropyrano[3,2-c]chromene derivatives with atom economy in a condensation reaction of 4-hydroxycoumarin, aldehydes, and malononitrile in a combinatorial fashion. The reaction gave excellent yields within short reaction times at room temperature under solvent-free grinding conditions. The products and ionic liquid could be conveniently separated from the reaction mixture, indicating that the whole process was performed as a green chemical transformation.      

Beiträge zur Chemie der Enaminoketone, 15. Mitt.: Die Dreikomponentensynthese von Hydrazinomethylenchromandionen und eine reduktive N-N-Bindungsspaltung von Phenylhydrazin

Zusammenfassung Die Dreikomponentenreaktion von 4-Hydroxycumarin, Orthoameisensäuretriethylester und verschieden substituierten Hydrazinen wird beschrieben.p-Nitrophenylhydrazin, Hydrazincarbonsäureester, Benzhydrazid und Phenylsemicarbazid liefern die erwarteten Hydrazinomethylenchromandione2a–f. Durch Umsetzung von 4-Hydroxycumarin-3-carbaldehyd mit Hydrazinen sind ebenfalls Hydrazinomethylenverbindungen (2g–k) zugänglich. Die Umsetzung von 4-Hydroxycumarin mit Orthoester und Phenylhydrazin oderp-Tolylhydrazin führt jedoch nicht zu2, sondern zu den Anilinomethylenchromandionen6a–b. Dies bedeutet eine reduktive Spaltung der N-N-Bindung unter sehr milden Reaktionsbedingungen zu Anilin und Ammoniak.

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Contributions to the chemistry of enaminoketones, XV: The three-component synthesis of hydrazinomethylene-chromandiones and a reductive N-N bond cleavage of phenylhydrazine

Summary The three-component reaction of 4-hydroxycoumarin, ethylorthoformiate, and different substituted hydrazines is described.p-Nitrophenylhydrazine, hydrazides and phenylsemicarbazide lead to the expected hydrazinomethylene-chromandiones2a–f. Reaction of 4-hydroxycoumarin, ethylorthoformiate, and phenylhydrazine orp-tolyl-hydrazine does not yield2, but the anilinomethylene-chromandiones6a–b. This indicates a reductive N-N bond cleavage to aniline and ammonia under mild conditions.