Showing papers in "Molecules in 2000"
TL;DR: In this paper, 3-(2-methylbenzimidazol-1-yl)propanoic acid hydrazide (1) with CS2/KOH gave oxadiazole 2 which underwent Mannich reaction to give triazole 4 which was treated with both aldehydes and acetic anhydride to give 5 and 6, respectively.
Abstract: Reaction of 3-(2-methylbenzimidazol-1-yl)propanoic acid hydrazide (1) with CS2/KOH gave oxadiazole 2 which underwent Mannich reaction to give 3. Compound 2 was treated with hydrazine hydrate to give triazole 4 which was treated with both aldehydes and acetic anhydride to give 5 and 6, respectively. Carbohydrazide 1 was reacted with ethyl acetoacetate, acetylacetone and aldehydes to give 7, 8 and 9, respectively. Cyclocondensation of 9 with thioglycolic and thiolactic acids gave 10 and 11, respectively. Some of these compounds showed potential antimicrobial activities.
316 citations
TL;DR: A review article dealing with the varied physiological activities of coumarin derivatives has been published, describing their anticoagulant, antibacterial, antihelminitic, hypothermal properties andvasodilatatory action as discussed by the authors.
Abstract: Z. M. Nofal*, M. I. El-Zahar and S. S. Abd El-KarimTherapeutical Chemistry Department, National Research Centre, Dokki, Cairo, EgyptFax: 00202 3370931, E-mail: znofal13@hotmail.com* Author to whom correspondence should be addressed.Received: 13 August 1999 / Accepted: 20 October 1999 / Published: 16 February 2000Abstract: A number of novel 3-bromo-4-methyl-7-methoxy-8-amino substituted coumarinsand 2-substituted 7-bromo-6-methyl-8H-pyrano-benzimidazoles, benzoxazoles and/or ben-zoxazine-8-ones were synthesized for the purpose of pharmacological evaluation. Some rep-resentative compounds showed antitumor activity in vitro on Ehrlich ascites carcinoma inthe preliminary testing.Keywords: Substituted coumarins, nitro reduction, benzylidinyl amino coumarins.IntroductionA review article dealing with the varied physiological activities of coumarin derivatives has beenpublished, describing their anticoagulant, antibacterial, antihelminitic, hypothermal properties andvasodilatatory action [1]. During the last twenty years, the study of the biological activities of couma-rin derivatives has been the aim of many researchers [2-5]. Also, the structure activity relationships ofcoumarins have revealed that the presence of substituted thiocarbonylmercaptoacetylamino derivativesis an essential feature of their pharmacological action. Based on these findings, we describe the synthe-sis of some compounds featuring different heterocyclic rings fused onto the coumarin moiety with theaim of obtaining more potent pharmacologically active compounds.
209 citations
TL;DR: The Advanced Organic Chemistry has found wide use as a text providing broad coverage of the structure, reactivity and synthesis of organic compounds as discussed by the authors, and has been used extensively in the literature.
Abstract: Since its original appearance in 1977, Advanced Organic Chemistry has found wide use as a text providing broad coverage of the structure, reactivity and synthesis of organic compounds.[...]
183 citations
TL;DR: Gaby et al. as discussed by the authors showed that the synthesis of 4-benzoyl-1,2-phenylenediamine with sodium pyruvate in acetic acid provided two products which were identified as 6-benzinoyl and 7-benenzoyl 3-methyl-2(1H)quinoxalinones (1a,b ).
Abstract: Department of Chemistry, Faculty of Science, Al-Azhar University at Assiut, Assiut 71524, EgyptFax: 002(088)325436, E-mail: m_elgaby@hotmail.comReceived: 29 April 2000 / Accepted: 13 June 2000 / Published: 18 June 2000Abstract: Condensation of 4-benzoyl-1,2-phenylenediamine with sodium pyruvate in aceticacid furnished two products which were identified as 6-benzoyl and 7-benzoyl-3-methyl-2(1H)quinoxalinones ( 1a ,b ). Fusion of 1a with aromatic aldehydes furnished the styryl de-rivatives 2a -c. Alkylation of 1a ,b with dimethyl sulphate or ethyl chloroacetate produced theN-alkyl derivatives 3a ,b and 4a ,b . Hydrazinolysis of the ester derivative 4a with hydrazinehydrate afforded the hydrazide derivative 5 which underwent condensation with aldehydes togive the corresponding hydrazone derivatives 6a ,b . In addition, chlorination of 1a withthionyl chloride afforded the 2-chloro derivative 7 which was subjected to reaction with s o-dium azide and n-butylamine to yield the corresponding tetrazolo (8) and n-butylamino (9)derivatives, respectively. The structures of the compounds prepared were confirmed by an a-lytical and spectral data. Also, some of the synthesized compounds were screened for antim i-crobial activity.Keywords: Quinoxalinones, 4-benzoyl-1,2-phenylenediamine, antimicrobial activity.
137 citations
TL;DR: A short review on cardiotonic steroids and their analogues is presented in this paper, where the natural, semisynthetic and synthetic derivatives, as well as their mechanism of action and structure-activity relationships are shown, with a special reference to aminoguanidine derivatives.
Abstract: A short review on cardiotonic steroids and their analogues is presented. The natural, semisynthetic and synthetic derivatives, as well as their mechanism of action and structure-activity relationships are shown, with a special reference to aminoguanidine derivatives.
127 citations
TL;DR: In this article, 5-arylidene derivatives of 2-imino-3-(4-arylthiazol-2-yl)-thiazolidin-4-ones and a series of their 5-ylidene derivative have been synthesized and tested for antifungal activity against seven agri-cultural fungi.
Abstract: Five derivatives of 2-imino-3-(4-arylthiazol-2-yl)-thiazolidin-4-ones and a series of their5-arylidene derivatives have been synthesized and tested for antifungal activity against seven agri-cultural fungi. 2-Imino-3-(2,4-dichloro-5-fluorophenylthiazol-2-yl)-4-thiazolidi-none and 2-imino-3-(2,4-dichlorophenylthiazol-2-yl)-4-thiazolidione, both of them new compounds, exhibited higherfungicidal effects than the other compounds prepared. Keywords: 2-imino-3-(4-arylthiazol-2-yl)-thiazolidin-4-ones, 5-arylidene derivatives, antifungalactivity. Introduction Thiazolidin-4-ones are important compounds due to their broad range of biological activities [1-7]. Over-views of their synthesis, properties, reactions and applications have been published[8,9]. 2-Imino-thiazolidin-4-ones have been found to have antifungal activity[10-12], and a convenient method for synthesis involves thereaction of 2-haloacetamides with potassium thiocyanate to produce 2-imino-thiazolidin-4-ones. The R- N -group at the 3-position of thiazolidin-4-ones may be varied to be alkyl, aryl, heterocyclic groups etc. It is alsowell known that the thiazole moiety can be important for significant biological activity [13-16].
109 citations
TL;DR: In this article, the main reactivity patterns of quinoid compounds with hydroxy groups have been reviewed and synthesized, and their syntheses and their main reactionivity patterns are discussed.
Abstract: Quinones having hydroxy groups directly attached to the quinone ring constitute a very interesting class of quinoid compounds. A great number of hydroxyquinones are found in nature and the majority of them exhibit unique biological activity. Their syntheses and their main reactivity patterns are reviewed in this paper.
100 citations
TL;DR: A conformationally rigid polyheterocycle which mimics the putative receptorbound conformation of dihydropyridine-type calcium channel modulators is prepared in a seven-step reaction sequence based on a Biginelli-type cyclocondensation reaction.
Abstract: A conformationally rigid polyheterocycle (3) which mimics the putative receptorbound conformation of dihydropyridine-type calcium channel modulators is prepared in a seven-step reaction sequence based on a Biginelli-type cyclocondensation reaction.
95 citations
TL;DR: Here, numerous winners of the Wolf prize from all chemical disciplines provide an overview of the new ideas and approaches that will shape this dynamic science over the forthcoming decades and so will have a decisive influence on living conditions.
Abstract: Here, numerous winners of the Wolf prize from all chemical disciplines provide an overview of the new ideas and approaches that will shape this dynamic science over the forthcoming decades and so will have a decisive influence on our living conditions.[...]
86 citations
TL;DR: Lin et al. as mentioned in this paper presented JChemPaint, an open source program for drawing 2D chemical structures, its current features, its envisioned further development and the principles enabling researchersand students at places all over the world to collaboratively develop such a program are de-scribed.
Abstract: Department of Chemistry, University of Nijmegen, The Netherlands* Author to whom correspondence should be addressed.Presented at the Third International Electronic Conference on Synthetic Organic Chemistry (ECSOC-3, http://reprints.net/ecsoc-3/E0004/e0004.html), September 1-30, 1999.Received: 26 January 2000 / Accepted: 27 January 2000 / Published: 28 January 2000Recommended for publication by Shu-Kun Lin (lin@mdpi.org)and Peter Ertl (peter.ertl@pharma.Novartis.com)Abstract: The open source program for drawing 2D chemical structures JChemPaint, itscurrent features, its envisioned further development and the principles enabling researchersand students at places all over the world to collaboratively develop such a program are de-scribed.Keywords: Chemical Markup Language, Java, Open Source, Structure Editor, StructureDiagram Generation.Introduction2D chemical structure editors are central tools in fields like chemoinformatics, computationalchemistry and synthetic chemistry. No matter if one wants to submit a structure query to a database,
79 citations
TL;DR: Heber et al. as discussed by the authors showed that 4-hydroxycoumarin cyclized through Michael addition to ben-zylidene malononitrile in pyridine as solvent to give a derivative of 2-aminopyrano[3,2-c]benzopyran(A) (Figure 1).
Abstract: Pharmaceutical Institute, Christian-Albrechts University of Kiel, Gutenbergstr. 76, D-24118 Kiel,GermanyTel.: (+49-431) 880-1118, Fax: (+49-431) 880-1352, E-mail: dheber@pharmazie.uni-kiel.de*Author to whom correspondence should be addressed.Received: 7 December 1999 / Accepted: 31 December 1999 / Published: 21 January 2000Abstract: Reaction of 4-hydroxy-6-methyl-2-pyrone (1a) as well as 4-hydroxy-6-methyl-2(1H)-pyridones (1b-d) with arylmethylene malononitriles or arylmethylene methyl cyano-acetates (2a-h) leads to the formation of the very stable 5,6-fused bicyclic 2-amino-4H-pyran derivatives 3a-3af.Keywords: pyrano[4,3-b]pyran, pyrano[3,2-c]pyridine, arylmethylene malononitrile, aryl-methylene cyanoacetate, Michael addition.IntroductionWiener et al. first published [1] that 4-hydroxycoumarin cyclized through Michael addition to ben-zylidene malononitrile in pyridine as solvent to give a derivative of 2-aminopyrano[3,2-c]benzopyran(A) (Figure 1). Later, Junek and Aigner [2] found a second case of this heterocyclization via additionof 4-hydroxy-6-methyl-2-pyrone (1a, “triacetic acid lactone”, Scheme 1) to tetracyanoethylene, thuspreparing a substituted 2-amino-4H,5H-pyrano[4,3-b]pyran (B). Many years thereafter, Shaker [3] re-
TL;DR: Several perinaphthenone/phenylphenalenone compounds were synthesized to publish a relationship between structure and antifungal activity against Mycosphaerella fijiensis and determine the relationship between phytoalexin structure and their antif fungus effects.
Abstract: Winston Quinones, Gustavo Escobar, Fernando Echeverri *, Fernando Torres, Yoni Rosero,Vi ctor Arango, Gloria Cardona and Adriana GallegoDepartment of Chemistry, Universidad de Antioquia, P. O. Box 1226, Medellin, ColombiaTel.: (57+4)2105658, Fax: (57+4)2330120, E-mail: echeveri@catios.udea.edu.coReceived : 18 January 2000 ; revised form 14 July 2000 / Accepted : 14 July 2000 / Published : 26 July 2000Abstract: Several perinaphthenone/phenylphenalenone compounds were synthesized to es-tablish a relationship between structure and antifungal activity against Mycosphaerella fijie n-sis. Substitutions on the unsaturated carbonyl system or addition of a phenyl group reducedantibiotic activity.Keywords: phenylphenalenones, synthesis, antifungal activity, Mycosphaerella fijiensis .IntroductionPhytoalexins are natural antibiotic compounds proposed as fungicides or templates for production ofnew pesticides [1]. Recently, the search for novel antifungal compounds has received special attentionas a result of an enhanced microbial resistance to current pesticides.Banana plants are affected by the pathogenic fungi Fusarium oxysporum var. cubensis type 4 andMycosphaerella fijiensis , causal agents of the diseases named Black Sigatoka and Panama Disease, r e-spectively. These diseases can drastically reduce banana production by as much as ca. 20% [2]. Undercolonization by these microorganisms or treatment of the leaves with kanamycin, banana plants producetwo types of phytoalexins, 9-phenylphenalenones (also known as musanolones [3]) and 4-phenylphenalenones [4], The main aim of the present work was to synthesize several structurally-relatedcompounds and to determine the relationship between phytoalexin structure and their antifungal effectsagainst M. fijiensis .Results and DiscussionThe planned synthetic approach involved a 1,4-addition of a Grignard reagent to a perinaphthenone,followed by reduction with DDQ, epoxidation with
TL;DR: A review of the use of the Claisen, Cope and related [3, 3]-sigmatropic rearrangements, sequential ("tandem") sigmoid rearrangement and the "ene" reaction in the syntheses of flavour and fragrance compounds is presented in this paper.
Abstract: A review of the use of the Claisen, Cope and related [3,3]-sigmatropic rearrangements, sequential ("tandem") sigmatropic rearrangements and the "ene" reaction in the syntheses of flavour and fragrance compounds is presented.
TL;DR: The book entitiled Pharmacophore Perception, Development, and Use in Drug Design, which has been released, is the first monograph dedicated to the topic of the pharmacophore.
Abstract: The book entitiled Pharmacophore Perception, Development, and Use in Drug Design, which has been just released [1], is the first monograph dedicated to the topic of the pharmacophore.[...]
TL;DR: The α-keto methylene group in 3,5-diaryl-2-cyclohexenones 2 and 3, 5-Diaryl cyclohexanones 8 have been used to obtain fused pyrazoles and isoxazoles.
Abstract: The α-keto methylene group in 3,5-diaryl-2-cyclohexenones 2 and 3,5-diarylcyclohexanones 8 have been used to obtain fused pyrazoles and isoxazoles. The new compounds were characterized by IR and 1H-NMR spectral data.
TL;DR: In this article, the authors summarized the mechanisms of the recently reported rearrangements resulting from inter-and/or intramolecular reactions of 2-imino-2H-chromene-3-carboxamides with different dinucleophiles.
Abstract: The present account summarizes the author's studies to elucidate the mechanisms of the recently reported rearrangements resulting from inter- and/or intramolecular reactions of 2-imino-2H-chromene-3-carboxamides with different dinucleophiles.
TL;DR: In this paper, the authors report some novel (or considerably improved) methods for the synthesis of aromatic iodides, (dichloroiodo)arenes, (diagramliodonium) halides, iodylarenes and diagramlionium salts, as well as some facile, oxidative anion metatheses in crude diaryliodoneium halides.
Abstract: This review reports some novel (or considerably improved) methods for the synthesis of aromatic iodides, (dichloroiodo)arenes, (diacetoxyiodo)arenes, iodylarenes and diaryliodonium salts, as well as some facile, oxidative anion metatheses in crude diaryliodonium halides and, for comparison, potassium halides. All these new results were obtained in our laboratory over the past decade (1990-2000). A full list of our papers dealing with the organic iodine(I, III and V) chemistry, covering exlusively the aromatic derivatives, is also provided.
TL;DR: Major findings in the search for non-peptide substances with neurotrophic potential are exposed, drawing special attention to cyclohexenonic long-chain fatty alcohols, a novel family of compounds that promote neuronal survival and neurite outgrowth.
Abstract: Neurotrophic factors play an important role in the development and maintenance of neurons, thus providing a suitable therapeutic approach for the treatment of neurodegenerative diseases. However, their clinical use has revealed problematic because of a number of technical and biological disadvantages. Among the different strategies proposed to overcome such difficulties, the search for non-peptide substances with neurotrophic potential is giving promising results. Here we will expose major findings in this field, drawing special attention to cyclohexenonic long-chain fatty alcohols, a novel family of compounds that promote neuronal survival and neurite outgrowth.
TL;DR: In this article, a tetrahedral structure for eleven (1:1) anhydrous acid-metal (II)nitrilotriacetates complexes is established for X-ray diffraction studies on the ligand and on eight of these complexes are described.
Abstract: IR and 1 H-NMR studies on nitrilotriacetic acid (H 3 NTA) suggest that the acidexists in the zwitterion form, which allows the existence of intermolecular hydrogenbonding. A tetrahedral structure is established for eleven (1:1) anhydrous acid-metal (II)nitrilotriacetates complexes. The ten Dq values for the colored complexes weredetermined spectrophotometrically. The pK a values for the eleven acid metal complexes[M(HNTA)].(OH 2 ) 3 ] were determined and compared with the corresponding pK a valuesof the [M(OH 2 ) n ] +2 ions and also with the log β 1 values of the corresponding [M(NTA)] - complexes. X-ray diffraction studies on the ligand and on eight of these complexes aredescribed. Keywords : nitrilotriacetic acid, nitrilotriacetates complexes, pK a values, X-ray diffraction Introduction A high content of chemical pollutants in soils and water may adversely affect plant and animalgrowth and in turn human health. Contamination of soils with such pollutants could be due to theapplication of chemical fertilizers, sewage, sludge, herbicides, industrial activities, etc. or irrigationwith contaminated water. Although a literature survey reveals that nitrilotriacetic acid (H
TL;DR: The insecticidal activities of several cyanohydrins, cyanohydrin esters and mono- terpenoid esters were evaluated and were among the most toxic compounds tested in topical and aquatic bioassays.
Abstract: The insecticidal activities of several cyanohydrins, cyanohydrin esters and mono- terpenoid esters (including three monoterpenoid esters of a cyanohydrin) were evaluated. Topical toxicity to Musca domestica L. adults was examined, and testing of many co m- pounds at 100 μg/fly resulted in 100% mortality. Topical LD 50 values of four compounds for M. domestica were calculated. Testing of many of the reported compounds to brine shrimp (Artemia franciscana Kellog) resulted in 100% mortality at 10 ppm, and two compounds caused 100% mortality at 1 ppm. Aquatic LC 50 values were calculated for five compounds for larvae of the yellow fever mosquito ( Aedes aegypti (L.)). Monoterpenoid esters were among the most toxic compounds tested in topical and aquatic bioassays.
TL;DR: In this article, 2-Amino-4,5-di-(2-furyl)furan-3-carbonitrile (1) reacted with triethyl orthoacetate to afford the corresponding 2-ethoxyimine derivative (2).
Abstract: 2-Amino-4,5-di-(2-furyl)furan-3-carbonitrile (1) reacted with triethyl orthoacetate to afford the corresponding 2-ethoxyimine derivative (2). The latter compound reacted with phenyl hydrazine, p-fluorobenzylamine and sodium hydrogen sulfide, respectively, to afford the corresponding furo[2,3-d]pyrimidine derivatives (3-5). Compound 1 also reacted with carbon disulfide and phenyl isocyanate to afford 5,6-di-(2-furyl)-1H-4H-furo[2,3-d]-[1,3-thiazin]-4-imino-2-thione (6) and 5,6-di-(2-furyl)-1H-3H-3-phenylfuro[2,3-d]pyrimidin-4-imine-2-one (7), respectively. Treatment of compound 2 with hydrazine hydrate at 0oC afforded compound 8, while on boiling 5,6-di-(2-furyl)-3H,4H-4-imino-2-methylfuro-[2,3-d]pyrimidin-3-amine (9) was isolated. Treatment of 9 with carbon disulfide, cyanogen bromide, ethyl cyanoacetate, diethyloxalate and triethyl orthoformate gave the corresponding furo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines (10-14). Reaction of 9 with isatin and N-acetyl isatin gave the condensation products 15 and 16 respectively.
TL;DR: These results show that the LSER model does not properly account for all molecular interactions involved in RP-HPLC, and three PCA factors are not quite sufficient to explain the whole data set for the three classes of stationary phases.
Abstract: The retention properties of eight alkyl, aromatic, and fluorinated reversed-phase high-performance liquid chromatography bonded phases were characterized through the use of linear solvation energy relationships (LSERs). The stationary phases were investigated in a series of methanol/water mobile phases. LSER results show that solute molecular size and hydrogen bond acceptor basicity under all conditions are the two dominant retention controlling factors and that these two factors are linearly correlated when either different stationary phases at a fixed mobile-phase composition or different mobile-phase compositions at a fixed stationary phase are considered. The large variation in the dependence of retention on solute molecular volume as only the stationary phase is changed indicates that the dispersive interactions between nonpolar solutes and the stationary phase are quite significant relative to the energy of the mobile-phase cavity formation process. PCA results indicate that one PCA factor is required to explain the data when stationary phases of the same chemical nature (alkyl, aromatic, and fluoroalkyl phases) are individually considered. However, three PCA factors are not quite sufficient to explain the whole data set for the three classes of stationary phases. Despite this, the average standard deviation obtained by the use of these principal component factors are significantly smaller than the average standard deviation obtained by the LSER approach. In addition, selectivities predicted through the LSER equation are not in complete agreement with experimental results. These results show that the LSER model does not properly account for all molecular interactions involved in RP-HPLC. The failure could reside in the V2 solute parameter used to account for both dispersive and cohesive interactions since "shape selectivity" predictions for a pair of structural isomers are very bad.
TL;DR: El-Gazzar et al. as discussed by the authors reported the utility of 3-methyl-2-methylthio-3,4-dihydrotheino[2,3-d]-pyrimidine-4-one derivatives.
Abstract: A.B.A. El-Gazzar and N.A. Hassan *Photochemistry Department, National Research Center, Cairo, EgyptF ax: 002-02-3370931 , E-mail: nasserabdelhamid@hotmail.comReceived : 2 August 1999 ; revised form 6 June 2000 / Accepted : 13 June 2000 / Published : 25 June 2000Abstract: Reaction of 2-hydrazino-3-methyl-3,4-dihydrothieno[2,3-d]pyrimidin-4-one de-rivatives 2a ,b with aliphatic acids afforded the thienotriazolopyrimidinone derivatives 3a -d ,with nitrous acid yielded tetrazolothienopyrimidinone derivatives 4a ,b and with carbon disu l-phide furnished 3-mercaptothienotriazolopyrimidinone derivatives 5a ,b . Also, 2a ,b reactedwith aldehydes to afford the arylhydrazones 6a -f which cyclized into thienotriazolopyrimid i-none derivatives 7a -f. Furthermore, 2a ,b condensed with ethyl acetoacetate and ethyl cyan o-acetate to afford 2-(1-pyrazolyl) derivatives 9a ,b and 10a ,b , respectively. On the other hand,2-hydrazino derivatives 2a ,b condensed with α-halo-ketones to yield thienpyrimidotriazinonederivatives 11a ,b and with β-diketones, to form 2-(1-pyrazolyl) derivatives 12a -f.Keywords: Pyrimidines, α-haloketones, β-diketones, β-ketoesters, aliphatic acids, NMRspectra .IntroductionThe biological [1-5], bactericidal [6], and medicinal [7,8] activities of thieno[2,3-d]-pyrimidine de-rivatives have stimulated considerable research in this field [9-12]. In continuation of our work on thesynthesis of fused pyrimidine derivatives [13], we report here the utility of 3-methyl-2-methylthio-3,4-dihydrotheino[2,3- d]pyrimidine-4-one derivative
TL;DR: The synthesis of 4-chloro-8-methylquinolin-2(1H)-one and its thione analogue is described in this paper, where nucleophilic substitution reactions of the 4chloro group were carried out to get new 4substituted 2-quinolinones and quinolinethiones, such as 4-sulfanyl, hydrazino, azido and amino derivatives, which are of important synthetic use.
Abstract: The synthesis of 4-chloro-8-methylquinolin-2(1H)-one and its thione analogue is described. Some nucleophilic substitution reactions of the 4-chloro group were carried out to get new 4-substituted 2-quinolinones and quinolinethiones, such as 4-sulfanyl, hydrazino, azido and amino derivatives, which are of important synthetic use. The structure of the new compounds was established by their elemental analysis, IR and 1H-NMR spectra. Also the mass fragmentation pattern of some products is discussed.
TL;DR: In this paper, a mild and efficient catalytic method for synthesis of 5-alkoxycarbonyl-4-aryl-3,4- dihydropyrimidin-2(1H)-ones using KSF montmorillonite as catalyst is described.
Abstract: A mild and efficient catalytic method for synthesis of 5-alkoxycarbonyl-4-aryl-3,4- dihydropyrimidin-2(1H)-ones using KSF montmorillonite as catalyst is described.
TL;DR: The rhodium(II)-catalyzed reaction of α-diazo ketones bearing tethered alkyne units represents a new and useful method for the construction of a variety of substitutedcyclopentenones.
Abstract: The rhodium(II)-catalyzed reaction of α-diazo ketones bearing tethered alkyneunits represents a new and useful method for the construction of a variety of substitutedcyclopentenones. The process proceeds by addition of the rhodium-stabilized carbenoidonto the acetylenic π-bond to give a vinyl carbenoid intermediate. The resulting rhodiumcomplex undergoes a wide assortment of reactions including cyclopropanation, 1,2-hydrogen migration, CH-insertion, addition to tethered alkynes and ylide formation. When2-alkynyl-2-diazo-3-oxobutanoates were treated with a Rh(II)-catalyst, furo[3,4- c ]furanswere formed in excellent yield. Keywords: .rhodium, catalyst, diazo, ketone, alkyne, cyclization, CH-insertion, ylide,furo[3,4- c ]furans Introduction The chemistry of transition metal carbene complexes has been a subject of intense activity over thepast two decades [1]. Current interest in this field stems from the role of metal carbenes in alkenemetathesis [2], in alkene and alkyne polymerization [3], in cyclopropanation chemistry [4], and asintermediates in an impressive array of synthetic methodology [5,6]. The intramolecular reactions of
TL;DR: In this article, the effect of microwave irradiation on the condensation of 3-formylchromones with 2-imino-1-methylimidazolidine-4-one (creatinine), 2-thioxoimidazlinine-1.4-oxobenzopyrans (thiohydantoin), and 3-ethylrhodanine (3-ethyl rhodanines) was investigated.
Abstract: Different types of 3-substituted 4H-4-oxobenzopyrans were prepared by microwave irradiation as well as by a classical method. The beneficial effect of microwave irradiation on the aldol condensation of 3-formylchromones with 2-imino-1-methylimidazolidine-4-one (creatinine), 2-thioxoimidazolidine-4-one (thiohydantoin) and 2-ethyl-2-thioxothiazolidin-4-one (3-ethylrhodanine) in different reaction media is described. Our results show that the effect of microwave irradiation on the reactions studied was a shortening of the reaction times and a smooth increase in the yields. The subsequent reactions of the product with some nucleophiles are discussed. The structure of the products was proven by elemental analysis, IR and NMR spectra.
TL;DR: In this paper, the regioselectivity of the model compound 4-methyl-1-thioxo-1,2,4,5-tetrahydro[1, 2,4]triazolo[4,3-a]quinazolin-5-one (3) towards different electrophiles was studied.
Abstract: The regioselectivity of the model compound 4-methyl-1-thioxo-1,2,4,5-tetrahydro[1,2,4]triazolo[4,3-a]quinazolin-5-one (3) towards different electrophiles was studied. Compound 3 reacts with alkyl and aryl halides to give the corresponding S-substituted derivatives. The reaction of the model thioamide with acyl halides proceeds by the formation of kinetically controlled S-acyl derivatives followed by a transacylation reaction to give the N2-acyl derivatives as thermodynamically controlled products. Theoretical DFT computational studies supported the explanation of these results. The synthesized compounds were characterized by FTIR, 1H-NMR, 13C-NMR, and mass spectroscopy.
TL;DR: 3D-QSAR studies on a series of 1,5-diarylpyrazoles that act as selective cyclooxygenase-2 (COX-2) inhibitors, using three different methods produced reasonably good predictive models with high cross-validated and conventional r 2 values in all the three cases.
Abstract: Selective cyclooxygenase inhibitors have attracted much attention in recent times in the design of new non-steroidal anti-inflammatory drugs (NSAID). 3D-QSAR studies have been performed on a series of 1,5-diarylpyrazoles that act as selective cyclooxygenase-2 (COX-2) inhibitors, using three different methods: comparative molecular field analysis (CoMFA) with partial least squares (PLS) fit; molecular field analysis (MFA) and; receptor surface analysis (RSA) with genetic function algorithms (GFA). The analyses were carried out on 30 analogues of which 25 were used in the training set and the rest considered for the test set. These studies produced reasonably good predictive models with high cross-validated and conventional r2 values in all the three cases.
TL;DR: In this paper, it was found that N-(2-cyanophenyl)chloromethanimidothioic chloride (2) and bis[N-(cyan-phenyl)-methoxymethylidene)ammonium chloride (6) are intermediates of this reaction, and identity of all reaction products was confirmed by GC-MS, FTIR, 1H and 13C NMR spectroscopy.
Abstract: N-(2-Cyanophenyl)chloromethanimidoyl chloride (3) was prepared from 2-isothiocyanatobenzonitrile by the reaction with sulfuryl chloride or gaseous chlorine in an inert solvent. It was found that N-(2-cyanophenyl)chloromethanimidothioic chloride (2) and bis[N-(cyanophenyl)chloromethanimidoyl] sulfide (7) are intermediates of this reaction. The chloride 3 was obtained also by a three-component one-pot reaction of N-(2-cyanophenyl)-formamide in the present of thionyl chloride and sulfuryl chloride. (2-Cyanophenyl)-(1-{[(2-cyanophenyl)-imino]methoxy}methylidene)ammonium chloride (6) was detected as a by-product of this reaction. Identity of all reaction products was confirmed by GC-MS, FTIR, 1H and 13C NMR spectroscopy.