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8 pages, 184 KiB

Open AccessArticle

One-Pot and Efficient Synthesis of Triazolo[1,2-a]indazole-triones via Reaction of Arylaldehydes with Urazole and Dimedone Catalyzed by Silica Nanoparticles Prepared from Rice Husk

by Hooshang Hamidian^1,*, Samieh Fozooni², Asadollah Hassankhani³ and Sayed Zia Mohammadi¹

¹ Department of Chemistry, Payame Noor University (PNU), P.O. Box 19395-369776175-559, TehranKerman, Iran

² Mining and Engineering Department of Zarand, Shahid Bahonar University, Kerman, 76169-14111, Iran

³ Department Institute of Materials Environmental Science, International Center for Science and High Technology and Environmental Science, P.O. Box 76315-117, Kerman, Iran

Molecules 2011, 16(11), 9041-9048; https://doi.org/10.3390/molecules16119041 - 26 Oct 2011

Cited by 42 | Viewed by 7463

Abstract

A novel synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by reaction of urazole, dimedone and aromatic aldehydes under conventional heating and microwave irradiation and solvent-free conditions using silica nanoparticles prepared from rice husk ash as catalyst is described. The new method features high yields, multicomponent reactions [...] Read more.

A novel synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by reaction of urazole, dimedone and aromatic aldehydes under conventional heating and microwave irradiation and solvent-free conditions using silica nanoparticles prepared from rice husk ash as catalyst is described. The new method features high yields, multicomponent reactions and environmental friendliness. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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12 pages, 211 KiB

Open AccessArticle

Microwave-Assisted Improved Synthesis of Oxazolidin-2-ones, Oxazolidine-2-thiones and Thiazolidine-2-thione Chiral Auxiliaries

by Rosmarbel Morales-Nava, Mario Fernández-Zertuche^* and Mario Ordóñez

Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos, 62209, Mexico

Molecules 2011, 16(10), 8803-8814; https://doi.org/10.3390/molecules16108803 - 20 Oct 2011

Cited by 23 | Viewed by 8807

Abstract

A microwave assisted method for the synthesis of some typical 4-substituted oxazolidinone chiral auxiliaries used in asymmetric synthesis is reported in this work. Under these conditions, treatment of (S)-phenylalaninol, (S)-phenylglycinol, (S)-valinol and (1S, 2R [...] Read more.

A microwave assisted method for the synthesis of some typical 4-substituted oxazolidinone chiral auxiliaries used in asymmetric synthesis is reported in this work. Under these conditions, treatment of (S)-phenylalaninol, (S)-phenylglycinol, (S)-valinol and (1S, 2R)-norephedrine with ethyl carbonate or carbon disulfide under the appropriate and specific microwave reaction conditions, led to an efficient synthesis of some oxazolidin-2-ones, oxazolidine-2-thiones and thiazolidine-2-thiones. The methodology reported in this paper provides these chiral auxiliaries with improved yields and a remarkable reduction on the reaction times, particularly in the case of thiazolidine-2-thiones, as compared with the conventional methods. All the auxiliaries prepared here show spectroscopic data in full agreement with those previously reported in the literature. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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12 pages, 226 KiB

Open AccessArticle

Efficient Microwave-Assisted Synthesis of Ionic Esterified Amino Acids

by Ricardo Cerón-Camacho, Jorge Aburto, Luisa E. Montiel, Eugenio A. Flores, Frisia Cuellar and Rafael Martínez-Palou^*

Dirección de Investigación y Posgrado, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, 07730 Mexico City, Mexico

Molecules 2011, 16(10), 8733-8744; https://doi.org/10.3390/molecules16108733 - 19 Oct 2011

Cited by 9 | Viewed by 6396

Abstract

In this work, an efficient microwave-assisted methodology for the esterification of unprotected α-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p [...] Read more.

In this work, an efficient microwave-assisted methodology for the esterification of unprotected α-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p-TsOH) to afford the pure products after a simple work-up procedure. This procedure can also be extended to the preparation of long and short chain alkyl and benzyl esters. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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13 pages, 511 KiB

Open AccessArticle

Microwave Assisted Organic Synthesis (MAOS) of Small Molecules as Potential HIV-1 Integrase Inhibitors

by Stefania Ferro^1,*, Sara De Grazia¹, Laura De Luca¹, Rosaria Gitto¹, Caterina Elisa Faliti¹, Zeger Debyzer² and Alba Chimirri¹

¹ Department of Medicinal Chemistry, University of Messina, Viale Annunziata, I-98168 Messina, Italy

² Molecular Medicine, Katholieke Universiteit Leuven and IRC KULAK, Kapucijnenvoer 33, B-3000 Leuven, Flanders, Belgium

Molecules 2011, 16(8), 6858-6870; https://doi.org/10.3390/molecules16086858 - 11 Aug 2011

Cited by 7 | Viewed by 6651

Abstract

Integrase (IN) represents a clinically validated target for the development of antivirals against human immunodeficiency virus (HIV). In recent years our research group has been engaged in the stucture-function study of this enzyme and in the development of some three-dimensional pharmacophore models which [...] Read more.

Integrase (IN) represents a clinically validated target for the development of antivirals against human immunodeficiency virus (HIV). In recent years our research group has been engaged in the stucture-function study of this enzyme and in the development of some three-dimensional pharmacophore models which have led to the identification of a large series of potent HIV-1 integrase strand-transfer inhibitors (INSTIs) bearing an indole core. To gain a better understanding of the structure-activity relationships (SARs), herein we report the design and microwave-assisted synthesis of a novel series of 1-H-benzylindole derivatives. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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11 pages, 250 KiB

Open AccessArticle

Microwave Assisted Synthesis of Novel Functionalized Hydantoin Derivatives and Their Conversion to 5-(Z) Arylidene-4H-imidazoles

by Sukanta Kamila, Haribabu Ankati and Edward R. Biehl^*

Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275, USA

Molecules 2011, 16(7), 5527-5537; https://doi.org/10.3390/molecules16075527 - 29 Jun 2011

Cited by 10 | Viewed by 6608

Abstract

2-(Alkyl-1-yl)-1H-imidazol-5(4H)-ones 5a–n were synthesized via nucleophilic substitution of the methylsulfanyl group of the corresponding 2-(methylthio)-1H-imidazol-5(4H)-ones 3a–c with suitably substituted secondary amines. The starting 2-thioxo- imidazolidin-4-ones 2a,2b were prepared by condensation of thiohydantoin and [...] Read more.

2-(Alkyl-1-yl)-1H-imidazol-5(4H)-ones 5a–n were synthesized via nucleophilic substitution of the methylsulfanyl group of the corresponding 2-(methylthio)-1H-imidazol-5(4H)-ones 3a–c with suitably substituted secondary amines. The starting 2-thioxo- imidazolidin-4-ones 2a,2b were prepared by condensation of thiohydantoin and benzo[b]-thiophene-3-carbaldehyde or benzofuran-3-carbaldehyde under microwave irracdiation (MW) conditions. 2-Methylthio derivatives 3a–c were prepared by treatment of 2a–b with methyl iodide in the presence of aqueous sodium hydroxide. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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21 pages, 298 KiB

Open AccessArticle

Microwave Assisted Synthesis of Some New Fused 1,2,4-Triazines Bearing Thiophene Moieties With Expected Pharmacological Activity

by Hosam A. Saad^1,2,*

, Mohamed M. Youssef^1,3 and Mosselhi A. Mosselhi^1,3

¹ Department of Chemistry, Faculty of Science, Taif University, Taif, 21974, Kingdom of Saudi Arabia

² Department of Chemistry, Faculty of Science, Zagazig University, Zagazig, 44511, Egypt

³ Department of Chemistry, Faculty of Science, Cairo University, Cairo, 12613, Egypt

Molecules 2011, 16(6), 4937-4957; https://doi.org/10.3390/molecules16064937 - 15 Jun 2011

Cited by 72 | Viewed by 8296

Abstract

Rapid and efficient solvent-free synthesis of 4-amino-3-mercapto-6-[2-(2-thienyl)vinyl]-1,2,4-triazin-5(4H)-one 1 under microwave irradiation is described. Some new fused heterobicyclic nitrogen systems such as 1,2,4-triazino[3,4-b][1,3,4]thiadiazinones, 1,3,4-thiadiazolo[2,3-c][1,2,4]triazinone and pyrazolo[5,1-c]-[1,2,4]triazine-7-carbonitrile, have been synthesized by treatment of 1 with bifunctional oxygen [...] Read more.

Rapid and efficient solvent-free synthesis of 4-amino-3-mercapto-6-[2-(2-thienyl)vinyl]-1,2,4-triazin-5(4H)-one 1 under microwave irradiation is described. Some new fused heterobicyclic nitrogen systems such as 1,2,4-triazino[3,4-b][1,3,4]thiadiazinones, 1,3,4-thiadiazolo[2,3-c][1,2,4]triazinone and pyrazolo[5,1-c]-[1,2,4]triazine-7-carbonitrile, have been synthesized by treatment of 1 with bifunctional oxygen and halogen compounds, CS₂/KOH and malononitrile via heterocyclization reactions, in addition to some uncondensed triazines. Structures of the products have been deduced from their elemental analysis and spectral data (IR, ¹H-NMR, ¹³C-NMR). Select new synthesized compounds were screened as anticancer agents, with some showing activity as cytotoxic agents against different cancer cell lines. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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11 pages, 197 KiB

Open AccessArticle

Microwave Assisted Synthesis and Unusual Coupling of Some Novel Pyrido[3,2-f][1,4]thiazepines

by Rasha M. Faty¹, Mohamed M. Youssef^1,*,† and Ayman M.S. Youssef²

¹ Department of Chemistry, Faculty of Science, Cairo University, Egypt

² Department of Chemistry, Faculty of Science, Fayoum University, Egypt

^† Current address: Department of Chemistry, Faculty of Science, Taif University, Saudi Arabia.

Molecules 2011, 16(6), 4549-4559; https://doi.org/10.3390/molecules16064549 - 31 May 2011

Cited by 15 | Viewed by 7456

Abstract

3-Amino-3-thioxopropanamide (1) reacted with ethyl acetoacetate to form 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide (2), which reacted with α-haloketones 3 to produce 2,3-disubstituted-8-hydroxy-6-methyl-2H,5H-pyrido[3,2-f]-[1,4]thiazepin-5-ones 4a-c. Benzoylation of 4c led to the formation of the dibenzoate derivative 9. Compounds 4a-c could be prepared stepwise [...] Read more.

3-Amino-3-thioxopropanamide (1) reacted with ethyl acetoacetate to form 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide (2), which reacted with α-haloketones 3 to produce 2,3-disubstituted-8-hydroxy-6-methyl-2H,5H-pyrido[3,2-f]-[1,4]thiazepin-5-ones 4a-c. Benzoylation of 4c led to the formation of the dibenzoate derivative 9. Compounds 4a-c could be prepared stepwise through the formation of S-alkylated derivatives 10a-c. Compounds 2, 4a-c, 9 and 10a-c were prepared using microwave as a source of heat, and gave better yields in shorter times than those achieved by traditional methods. Coupling of 4a-c with arenediazonium chlorides proceeded unusually to give the 6-hydroxy-4-methyl-2-(arylazo)thieno[2,3-b]pyridin-3(2H)-one ring contraction products 14. Structures of the newly synthesized compounds were proven by spectral and chemical methods. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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11 pages, 300 KiB

Open AccessArticle

Microwave-Assisted and Efficient Solvent-free Knoevenagel Condensation. A Sustainable Protocol Using Porous Calcium Hydroxyapatite as Catalyst

by Siham Mallouk¹, Khalid Bougrin^1,*, Abdelaziz Laghzizil² and Rachid Benhida^3,*

¹ Laboratoire de Chimie des Plantes et de Synthèse Organique et Bioorganique, Université Mohammed V-Agdal, Faculté des Sciences, B.P. 1014 R.P, Rabat, Maroc

² Laboratoire de Chimie Physique Générale, Université Mohammed V-Agdal, Faculté des Sciences, B.P. 1014 R.P, Rabat, Maroc

³ Laboratoire de Chimie des Molécules Bioactives et des Arômes, UMR 6001 CNRS, Institut de Chimie de Nice, Université de Nice-Sophia Antipolis, 28 avenue de Valrose, 06108 Nice Cedex 2, France

Molecules 2010, 15(2), 813-823; https://doi.org/10.3390/molecules15020813 - 4 Feb 2010

Cited by 65 | Viewed by 12803

Abstract

A sustainable Knoevenagel condensation of a series of aldehydes with malononitrile and ethyl cyanoacetate is described. The process is based on the combination of microwave activation and hydroxyapatite catalysis under solvent-free conditions. Products are obtained in and high yields after short reaction times. [...] Read more.

A sustainable Knoevenagel condensation of a series of aldehydes with malononitrile and ethyl cyanoacetate is described. The process is based on the combination of microwave activation and hydroxyapatite catalysis under solvent-free conditions. Products are obtained in and high yields after short reaction times. The effects of the specific surface of porous calcium hydroxyapatite and microwave activation are discussed. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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8 pages, 510 KiB

Open AccessArticle

Application of the Molecular Combing Technique to Starch Granules

by Hua Li¹, Zhong-Dong Liu^1,*, Liu Boxiang², Jian-Hui Chen¹, You-Ning Sun¹, Xiao-Ling Lv³, Ze-Sheng Zhang³, Pin Sun³, Pin Zhang¹ and Yang-Li Wang¹

¹ Department of Food Science, Henan University of Technology, Zhengzhou 450052, Henan, China

² Tianjin University, Weijin Road 92#, Tianjin, 300072, China

³ College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, No 29, the 13 Avenue of Teda, Tianjin 300457, China

Molecules 2009, 14(10), 4079-4086; https://doi.org/10.3390/molecules14104079 - 12 Oct 2009

Cited by 2 | Viewed by 11745

Abstract

The molecular combing technique was used to dissociate the nanostructural units of starch granules from the starch fragments after a gelatinization process. With the help of atomic force microscopy (AFM), we observed that some nanostructural chains were just flowing out of the granules. [...] Read more.

The molecular combing technique was used to dissociate the nanostructural units of starch granules from the starch fragments after a gelatinization process. With the help of atomic force microscopy (AFM), we observed that some nanostructural chains were just flowing out of the granules. It proves that there are substantive nanostructural units in the starch granules, a phenomenon not previously observed, so these nanostructural units were defined as suspected intermediates. Furthermore, we conclude that blocklets of starch granules are formed through twisting or distortion of nanochains. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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11 pages, 438 KiB

Open AccessArticle

Microwave-Assisted Synthesis and Crystal Structure of Oxo(diperoxo)(4,4'-di-tert-butyl-2,2'-bipyridine)-molybdenum(VI)

by Tatiana R. Amarante¹, Filipe A. Almeida Paz¹, Sandra Gago¹, Isabel S. Gonçalves¹, Martyn Pillinger¹, Alírio E. Rodrigues² and Marta Abrantes^2,*

¹ Department of Chemistry, CICECO, University of Aveiro, 3810–193 Aveiro, Portugal

² Laboratory of Separation and Reaction Engineering, Associate Laboratory LSRE/LCM, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200–465, Porto, Portugal

Molecules 2009, 14(9), 3610-3620; https://doi.org/10.3390/molecules14093610 - 16 Sep 2009

Cited by 23 | Viewed by 14396

Abstract

The oxodiperoxo complex MoO(O₂)₂(tbbpy) (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine) was isolated from the reaction of MoO₂Cl₂(tbbpy) in water under microwaveassisted heating at 120 ºC for 4 h. The structure of the oxodiperoxo complex was [...] Read more.

The oxodiperoxo complex MoO(O₂)₂(tbbpy) (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine) was isolated from the reaction of MoO₂Cl₂(tbbpy) in water under microwaveassisted heating at 120 ºC for 4 h. The structure of the oxodiperoxo complex was determined by single crystal X-ray diffraction. The Mo^VI centre is seven-coordinated with a geometry which strongly resembles a highly distorted bipyramid. Individual MoO(O₂)₂(tbbpy) complexes are interdigitated along the [010] direction to form a column. The crystal structure is formed by the close packing of the columnar-stacked complexes. Interactions between neighbouring columns are essentially of van der Waals type mediated by the need to effectively fill the available space. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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16 pages, 270 KiB

Open AccessArticle

Microwave-Assisted Solvent-Free Acetylation of Cellulose with Acetic Anhydride in the Presence of Iodine as a Catalyst

by Jing Li¹, Li-Ping Zhang¹, Feng Peng², Jing Bian¹, Tong-Qi Yuan¹, Feng Xu¹ and Run-Cang Sun^1,2,*

¹ College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China

² State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China

Molecules 2009, 14(9), 3551-3566; https://doi.org/10.3390/molecules14093551 - 11 Sep 2009

Cited by 150 | Viewed by 18543

Abstract

In this work an optimization of the solvent-free acetylation of cellulose with acetic anhydride under microwave heating with iodine as a catalyst was performed. The optimized parameters included the microwave irradiation power from 300 W to 800 W, the reaction time between 5 [...] Read more.

In this work an optimization of the solvent-free acetylation of cellulose with acetic anhydride under microwave heating with iodine as a catalyst was performed. The optimized parameters included the microwave irradiation power from 300 W to 800 W, the reaction time between 5 to 40 min, the reaction temperature from 80 to 130 °C, and the amount of iodine from 1 to 15 mol%. The extent of the acetylation was measured by yield and the degree of substitution (DS), which was determined by a back-titration method. Acetylated cellulose was characterized by FT-IR, CP/MAS ¹³C-NMR, WRXD, and thermogravimetric analysis. The results showed that within the range of catalyst amounts studied, the DS increased as the amount of iodine used increased, however, it was barely affected by microwave output. It was also found that the reaction time and temperature had an active influence on the extent of acetylation, however, this did not mean that at the higher temperature a better acetylation of cellulose would be obtained. The optimal reaction time and temperature found in this work were 30 min and 130 °C. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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14 pages, 324 KiB

Open AccessArticle

Fast and Green Microwave-Assisted Conversion of Essential Oil Allylbenzenes into the Corresponding Aldehydes via Alkene Isomerization and Subsequent Potassium Permanganate Promoted Oxidative Alkene Group Cleavage

by Thi X. Thi Luu¹, Trinh To Lam², Thach Ngoc Le² and Fritz Duus^1,*

¹ Department of Science, Systems, and Models, Roskilde University, P.O. Box 260, DK-4000, Roskilde, Denmark

² Department of Organic Chemistry, University of Science, National University of Ho Chi Minh City, 227 Nguyen Van Cu, Ho Chi Minh City, Vietnam

Molecules 2009, 14(9), 3411-3424; https://doi.org/10.3390/molecules14093411 - 3 Sep 2009

Cited by 37 | Viewed by 16369

Abstract

Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step “green” reaction pathway based on a solventless alkene group isomerization by KF/Al₂O₃ to form the corresponding 1-arylpropene and a subsequent [...] Read more.

Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step “green” reaction pathway based on a solventless alkene group isomerization by KF/Al₂O₃ to form the corresponding 1-arylpropene and a subsequent solventless oxidation of the latter to the corresponding benzaldehyde by KMnO₄/CuSO₄·5H₂O. The assistance by microwave irradiation results in very short reaction times (<15 minutes). The green conversion of eugenol (4-allyl-2-methoxyphenol) into vanillin (4-hydroxy-3-methoxybenzaldehyde) has been carried out in a similar way, requiring however two additional microwave-assisted synthetic steps for acetylation of the hydroxy group prior to the oxidation reaction, and for the final deacetylation of vanillin acetate (4-acetoxy-3-methoxybenzaldehyde) by KF/Al₂O₃ under solvent-free conditions, respectively. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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9 pages, 233 KiB

Open AccessArticle

Cross-Cyclotrimerization with Two Nitriles as a Synthetic Pathway to Unsymmetrically 3,3’-Disubstituted bis(Tetrahydroisoquinolines)

by Aneta Kadlčíková¹ and Martin Kotora^1,2,*

¹ Department of Organic and Nuclear Chemistry, and Center for Structural and Synthetic Application of Transition Metal Complexes, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Praha 2, Czech Republic

² Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Praha 6, Czech Republic

Molecules 2009, 14(8), 2918-2926; https://doi.org/10.3390/molecules14082918 - 10 Aug 2009

Cited by 18 | Viewed by 10660

Abstract

Microwave assisted CpCo(CO)₂ catalyzed cross-cyclotrimerizations of 1,7,9,15-hexadecatetrayne with two different nitriles to give unsymmetrically substituted bis(tetrahydroisoquinolines) was studied. The reaction proceeded with a range of alkyl and aryl nitriles with reasonable isolated yields. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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14 pages, 211 KiB

Open AccessArticle

Efficient Microwave Assisted Syntheses of 2,5-Diketopiperazines in Aqueous Media

by Lemuel Pérez-Picaso¹, Jaime Escalante¹, Horacio F. Olivo² and María Yolanda Rios^1,*

¹ Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, México

² Medicinal and Natural Products Chemistry, The University of Iowa, Iowa City, IA 52242, USA

Molecules 2009, 14(8), 2836-2849; https://doi.org/10.3390/molecules14082836 - 31 Jul 2009

Cited by 47 | Viewed by 12781

Abstract

Aqueous in situ one-pot N-Boc-deprotection-cyclization of Nα-Boc-dipeptidyl-tert-butyl and methyl esters under microwave irradiation afforded 2,5-diketopiperazines (DKPs) in excellent yields. This protocol is rapid, safe, environmentally friendly, and highly efficient, and showed that the tert-butoxy moiety is also an excellent leaving group [...] Read more.

Aqueous in situ one-pot N-Boc-deprotection-cyclization of Nα-Boc-dipeptidyl-tert-butyl and methyl esters under microwave irradiation afforded 2,5-diketopiperazines (DKPs) in excellent yields. This protocol is rapid, safe, environmentally friendly, and highly efficient, and showed that the tert-butoxy moiety is also an excellent leaving group for these cyclizations. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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7 pages, 224 KiB

Open AccessArticle

Extraction with SPME and Synthesis of 2-Methyl-6-vinylpyrazine by a ‘One Pot’ Reaction Using Microwaves

by Norma Robledo¹, Jaime Escalante^2,* and René Arzuffi¹

¹ Centro de Desarrollo de Productos Bióticos, IPN. Km. 8.5 Carretera Yautepec-Jojutla Yautepec, Morelos, C.P. 62731, Mexico

² Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos. Av. Universidad No. 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Mor., Mexico

Molecules 2009, 14(6), 2160-2166; https://doi.org/10.3390/molecules14062160 - 15 Jun 2009

Cited by 4 | Viewed by 10970

Abstract

A synthesis of 2-methyl-6-vinylpyrazine was carried out by way of a ‘one pot’ reaction. In order to establish the efficiency of this synthesis the extraction of the volatiles released by male papaya fruit flies was performed by SPME (solid phase micro-extraction). The compound [...] Read more.

A synthesis of 2-methyl-6-vinylpyrazine was carried out by way of a ‘one pot’ reaction. In order to establish the efficiency of this synthesis the extraction of the volatiles released by male papaya fruit flies was performed by SPME (solid phase micro-extraction). The compound was separated and identified using GC/MSD (gas chromatography/mass spectrometry detector). Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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10 pages, 152 KiB

Open AccessArticle

Synthesis of γ-Nitro Aliphatic Methyl Esters Via Michael Additions Promoted by Microwave Irradiation

by Jaime Escalante^* and Francisco D. Díaz-Coutiño

Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos. Av. Universidad No. 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Mor., Mexico

Molecules 2009, 14(4), 1595-1604; https://doi.org/10.3390/molecules14041595 - 21 Apr 2009

Cited by 18 | Viewed by 13652

Abstract

A simple and efficient protocol has been developed for the direct synthesis of γ-nitrobutyric acid methyl esters under microwave irradiation. This methodology reduces reaction times from days to minutes, compared to conventional conditions. Additionally, these conditions increased yields and provided cleaner reactions. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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8 pages, 117 KiB

Open AccessCommunication

Phosphotungstic Acid: An Efficient, Cost-effective and Recyclable Catalyst for the Synthesis of Polysubstituted Quinolines

by Minoo Dabiri^1,* and Sahareh Bashiribod²

¹ Department of Chemistry, Faculty of Science, Shahid Beheshti University, G. C., Evin 1983963113, Tehran, Iran

² Department of Marine Biology, Faculty of Biological Scinences Shahid Beheshti University, G. C., Evin, Tehran, Iran

Molecules 2009, 14(3), 1126-1133; https://doi.org/10.3390/molecules14031126 - 12 Mar 2009

Cited by 37 | Viewed by 12447

Abstract

Phosphotungstic acid (H₃PW₁₂O₄₀) was used as an efficient and recyclable catalyst for the synthesis of polysubstituted quinolines through the Friedländer condensation of 2-aminoarylketone with carbonyl compounds, which was achieved by conventional heating under solvent-free conditions. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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9 pages, 72 KiB

Open AccessArticle

Microwave Assisted Reactions of Some Azaheterocylic Compounds

by Gheorghita Zbancioc, Vasilichia Bejan, Marian Risca, Costel Moldoveanu and Ionel I. Mangalagiu^*

“Al. I. Cuza” University of Iasi, Organic Chemistry Department, Bd. Carol 11, 700506 Iasi, Romania

Molecules 2009, 14(1), 403-411; https://doi.org/10.3390/molecules14010403 - 15 Jan 2009

Cited by 32 | Viewed by 15321

Abstract

A fast, general, environmentally friendly and facile method for preparation of five- and six-membered ring diazaheterocylic salts under microwave irradiation is presented. The N-alkylation reactions of imidazole, pyrimidine, pyridazine and phthalazine have been studied. The microwaves remarkably accelerated these N-alkylations, the [...] Read more.

A fast, general, environmentally friendly and facile method for preparation of five- and six-membered ring diazaheterocylic salts under microwave irradiation is presented. The N-alkylation reactions of imidazole, pyrimidine, pyridazine and phthalazine have been studied. The microwaves remarkably accelerated these N-alkylations, the reaction times decreased dramatically, the reaction conditions were milder, the consumed energy decreased considerably and the amount of solvents used was reduced substantially. Consequently, the microwave assisted alkylation of N-containing heterocycles could be considered eco-friendly. In some cases, under MW irradiation the yields are also higher. A comparative study of microwave vs. classical conditions (liquid solvents) has been done. Twelve new diazaheterocylic salts of potential practical interest were obtained. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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7 pages, 151 KiB

Open AccessArticle

Dodecatungstophosphoric Acid (H₃PW₁₂O₄0), Samarium and Ruthenium (ІІІ) Chloride Catalyzed Synthesis of Unsaturated 2-Phenyl-5(4H)-oxazolone Derivatives under Solvent-free Conditions

by Ahmad Momeni Tikdari^1,*, Samieh Fozooni¹ and Hooshang Hamidian²

¹ Department of Chemistry, Shahid Bahonar University of Kerman, Kerman, 76135-133, Iran

² Department of Chemistry, Payame Noor University (PNU), Kerman, Iran

Molecules 2008, 13(12), 3246-3252; https://doi.org/10.3390/molecules13123246 - 18 Dec 2008

Cited by 33 | Viewed by 11023

Abstract

We found that dodecatungstophosphoric acid (H₃PW₁₂O₄0), samarium and ruthenium(III) chloride act as efficient catalysts for synthesis of unsaturated 2-phenyl-5(4H)oxazolone derivatives under solvent-free conditions. The key features of the reported protocols are short reaction times, high yields of [...] Read more.

We found that dodecatungstophosphoric acid (H₃PW₁₂O₄0), samarium and ruthenium(III) chloride act as efficient catalysts for synthesis of unsaturated 2-phenyl-5(4H)oxazolone derivatives under solvent-free conditions. The key features of the reported protocols are short reaction times, high yields of products, ambient conditions and simple workup. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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24 pages, 440 KiB

Open AccessReview

MAOS and Medicinal Chemistry: Some Important Examples from the Last Years

by Nailton M. Nascimento-Júnior^1,2,*, Arthur E. Kümmerle³, Eliezer J. Barreiro^1,2,4 and Carlos A. M. Fraga^1,2,4,*

¹ Laboratório de Avaliação e Síntese de substâncias Bioativas (LASSBio), Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, PO Box 68023, Rio de Janeiro 21941-902, RJ, Brazil

² Programa de Pós-Graduação em Química, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, RJ, Brazil

³ Departamento de Química, Instituto de Ciências Exatas, Universidade Federal Rural do Rio de Janeiro, Seropédica 23890-000, RJ, Brazil

⁴ Programa de Pós-Graduação em Farmacologia e Química Medicinal, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil

Molecules 2011, 16(11), 9274-9297; https://doi.org/10.3390/molecules16119274 - 7 Nov 2011

Cited by 23 | Viewed by 7181

Abstract

This review aims to highlight microwave-assisted organic synthesis as applied to medicinal chemistry in the last years, showing some reactions performed under microwave irradiation for the synthesis of distinct structurally molecules of biological interest, divided into the following groups: antineoplastics, anti-inflammatory, antimicrobial agents, [...] Read more.

This review aims to highlight microwave-assisted organic synthesis as applied to medicinal chemistry in the last years, showing some reactions performed under microwave irradiation for the synthesis of distinct structurally molecules of biological interest, divided into the following groups: antineoplastics, anti-inflammatory, antimicrobial agents, antivirals, agents for the treatment of neglected diseases and central nervous system-acting prototypes. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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37 pages, 532 KiB

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Microwave Multicomponent Synthesis

by Helmut M. Hügel

School of Applied Sciences, RMIT University, GPO Box 2476V Melbourne, Victoria 3001, Australia

Molecules 2009, 14(12), 4936-4972; https://doi.org/10.3390/molecules14124936 - 1 Dec 2009

Cited by 122 | Viewed by 15326

Abstract

In the manner that very important research is often performed by multidisciplinary research teams, the applications of multicomponent reactions involving the combination of multiple starting materials with different functional groups leading to the higher efficiency and environmentally friendly construction of multifunctional/complex target molecules [...] Read more.

In the manner that very important research is often performed by multidisciplinary research teams, the applications of multicomponent reactions involving the combination of multiple starting materials with different functional groups leading to the higher efficiency and environmentally friendly construction of multifunctional/complex target molecules is growing in importance. This review will explore the advances and advantages in microwave multicomponent synthesis (MMS) that have been achieved over the last five years. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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