Cyclization
Mostrando 1-12 de 259 artigos, teses e dissertações.
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1. Improvements in Methyl-Bambus[6]uril Synthesis Yield
Bambus[n]uril synthesis may be challenging, and it is frequently achieved with low purity and low yields. We have studied the effect of different anions on the synthesis of bambus[6]uril, especially in terms of yield, exploring template effects driven by anions in the reaction medium. The influence of the anions is evident on such syntheses and ClO4− parti
J. Braz. Chem. Soc.. Publicado em: 2020-11
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2. ONE-POT DIASTEREOSELECTIVE SYNTHESIS OF CHIRAL TRICYCLIC L-CYSTEINE AND D-PENICILLAMINE DERIVATIVES: A LABORATORY EXPERIMENT
A one-pot diastereoselective synthesis of thiazolidine-ring fused systems derived from enantiomerically pure amino acids, L-cysteine or D-penicillamine, and achiral succindialdehyde is described as an experiment to be carried out by upper-division undergraduate students in a laboratory classroom. Reactions were performed under mild conditions, the products w
Quím. Nova. Publicado em: 2020-01
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3. SYNTHESIS OF MESOPOROUS γ-ALUMINA AND ITS CATALYTIC PERFORMANCE IN DICHLOROPROPANOL CYCLIZATION
This paper discusses the synthesis and resulting catalytic performance of mesoporous alumina using aluminum isopropoxide as the aluminum source, and synthesized organosiloxane KH560-540 as template. The effects of the hydrothermal conditions, as well as the amount of templating agent at pH values of 5-9 on the structure of the synthesized mesoporous alumina
Quím. Nova. Publicado em: 21/10/2019
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4. Imidazo[1,2-a]pyridine A3-Coupling Catalyzed by a Cu/SiO2 Material
In this work, we report the preparation of a copper-silica material (Cu/SiO2) by a sol-gel methodology and its characterization concerning composition and textural properties. The Cu/SiO2 material was successfully applied as a Lewis acid heterogeneous catalyst for the A3-coupling from 2-aminopyridine, aldehydes and alkynes to imidazo[1,2-a]pyridines (45-82%)
J. Braz. Chem. Soc.. Publicado em: 16/09/2019
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5. Alternative Non-Ionic Pathway for Uncatalyzed Prins Cyclization: DFT Approach
Density functional theory calculations (ωB97X-D/6-311++G(d,p)) are employed to investigate an alternative pathway for Prins-like cyclization. Although strong acids usually catalyze this reaction, 4-amino-1,3-dioxanes are rapidly obtained in high yields without catalyst when benzenamines and acetaldehyde react at low temperatures, in aqueous medium. Consider
J. Braz. Chem. Soc.. Publicado em: 12/08/2019
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6. Streamlined Synthesis of 6-((1H-1,2,3-Triazol-4-yl)methyl)-1H-pyrrolo [3,4-d]pyridazin-1-one System via Sequential N-Alkylation, CuAAC, and [4 + 2] Cyclization Reactions
An efficient sequential three-step reaction methodology for the synthesis of three new series-1-(prop-2-yn-1-yl)-1H-pyrroles, methyl 4-acetyl-1-((1H-1,2,3-triazol-4-yl)methyl)-1H-pyrrole-3-carboxylates and 6-((1H-1,2,3-triazol-4-yl)methyl)-2,6-dihydro-1H-pyrrolo[3,4-d]pyridazin-1-ones-is reported. The methodology comprises: (i) N-alkylation reactions of poly
J. Braz. Chem. Soc.. Publicado em: 23/05/2019
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7. Synthesis of some novel pyrimidine, thiophene, coumarin, pyridine and pyrrole derivatives and their biological evaluation as analgesic, antipyretic and anti-inflammatory agents
Pyrimidine derivative 3 was afforded through the reaction of compound (1) with 5-ureidohydantion (2). Product 3 underwent a cyclization to produce fused pyrimidine derivative 7, although the latter product 7 was synthesized through one step via the reaction of compound (1) with 5-ureidohydantion (2) using another catalyst. Compound 3 was oriented to react wi
Braz. J. Pharm. Sci.. Publicado em: 08/04/2019
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8. A Facile Synthesis of Novel Isatinspirooxazine Derivatives and Potential in vitro Anti-Proliferative Activity
Novel isatinspirooxazine derivatives were designed and synthesized as potential anti-proliferative agents. The new compounds were obtained from aldol condensation reactions between isatin and 3-(hydroxyimino)butan-2-one in the presence of an organic base in order to generate an aldol adduct, followed by cyclization in trifluoroacetic acid, providing the desi
J. Braz. Chem. Soc.. Publicado em: 2019-01
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9. Total Synthesis of Altissimacoumarin D, a Small Molecule Sirtuin1 Activator
The total synthesis of the plant natural product altissimacoumarin D was achieved by the Mitsunobu alkylation of isofraxidin by geraniol. Isofraxidin was prepared from 2,4-dihydroxybenzaldehyde in five steps. The key reaction was the Knoevenagel condensation of an ortho-hydroxybenzaldehyde with Meldrum's acid under neutral conditions in water and one-pot aci
J. Braz. Chem. Soc.. Publicado em: 2018-05
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10. Biosynthetic Insights into p-Hydroxybenzoic Acid-Derived Benzopyrans in Piper gaudichaudianum
Piper gaudichaudianum Kunth (Piperaceae) accumulates gaudichaudianic acid, a prenylated benzopyran, as its major component. Interestingly, this trypanocidal compound occurs as a racemic mixture. Herein, transcriptomic investigations of Piper gaudichaudianum using the RNA-seq approach are reported, and from the analysis of the transcripts expressed it was pos
J. Braz. Chem. Soc.. Publicado em: 2018-05
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11. ABORDAGEM DIDÁTICA PARA O DESENVOLVIMENTO DE MOLÉCULAS BIOATIVAS: REGRA DOS CINCO DE LIPINSKI E PREPARAÇÃO DE HETEROCICLO 1,3,4-OXADIAZOL EM FORNO DE MICRO-ONDAS DOMÉSTICO
In Brazil, the development of new chemical entities (NEQ) is still limited to small advances in the academic and public research sectors, the authors understand that this is a sector of the pharmaceutical industry that needs encouragement. Accepting that education transforms society, educate students in the development of bioactive molecules, it’s a way to
Quím. Nova. Publicado em: 2018-01
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12. In vivo chemotherapeutic insight of a novel isocoumarin (3-hexyl-5,7-dimethoxy-isochromen-1-one): Genotoxicity, cell death induction, leukometry and phagocytic evaluation
Abstract Chemotherapy is one of the major approaches for the treatment of cancer. Therefore, the development of new chemotherapy drugs is an important aspect of medicinal chemistry. Chemotherapeutic agents include isocoumarins, which are privileged structures with potential antitumoral activity. Herein, a new 3-substituted isocoumarin was synthesized from 2-
Genet. Mol. Biol.. Publicado em: 2017-09