Regioselectivity
Mostrando 1-12 de 35 artigos, teses e dissertações.
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1. Rhodium(III)-Catalyzed Addition of Indoles with Boc-Imines via C-H Bond Activation
A rhodium-catalyzed alkylation reaction of indoles with N-Boc-imines has been developed via C-H activation to afford a series of substituted 2-indolyl-methanamine derivatives with good functional group tolerance and regioselectivity. A wide range of indole-based alkylation products could be obtained in up to 95% yield.
J. Braz. Chem. Soc.. Publicado em: 2018-06
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2. MÉTODOS AMBIENTALMENTE AMIGÁVEIS PARA A IODAÇÃO REGIOSSELETIVA DA 3,7,3’,4’-TETRAMETOXI-QUERCETINA
Halogenated compounds are valuable substrates for the field of organic synthesis and more specifically as reagents for coupling reactions. Environmental friendly procedures for regioselective iodination is the aim of this study, using four different methods previously described in the literature, that embrace green chemistry concepts, to obtain the 6- and 8-
Quím. Nova. Publicado em: 2018-05
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3. Natural Organic Acid as Green Catalyst for Xanthenones Synthesis: Methodology, Mechanism and Calcium Channel Blocking Activity
Xanthenones were synthesized via one-pot tricomponent reaction, under solvent-free conditions, using aldehydes, phenolic and cyclic 1,3-dicarbonyl compounds. Natural organic acids (NOAs), compounds present in many living metabolisms, were used as potential green catalysts. NOA are considered to be more eco-friendly and user-friendly alternative to traditiona
J. Braz. Chem. Soc.. Publicado em: 2017-12
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4. NMR Studies on [2 + 3] Cycloaddition of Nitrile Oxides to Polyunsaturated Medium Size Rings
Site selectivity, regioselectivity and stereoselectivity of [2 + 3] cycloaddition of 4-trifluoromethylbenzonitrile oxide to polyunsaturated medium size rings including 1,5,9-cyclododecatriene, 11-membered sesquiterpenes, 1,3-cyclooctadiene and 5-vinyl-2-norbornene were examined. Site selectivity was correlated with electron charges of alkenyl carbon atoms. S
J. Braz. Chem. Soc.. Publicado em: 2016-11
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5. Influence of different protecting groups on the regioselectivity of the hydrotelluration reaction of hydroxy alkynes
A influência de grupos protetores na síntese régio- e estereosseletiva de teluretos vinílicos preparados a partir de BuTeNa e álcoois propargílicos e homopropargílicos demonstrou que o eter de silício TIPS é útil como grupo régio-dirigente. A aplicação da metodologia na síntese de um fragmento do (±)-Seselidiol, um produto natural, demonstrou
Journal of the Brazilian Chemical Society. Publicado em: 2010
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6. Cloração do anisol, tolueno e nitrobenzeno com ácido tricloroisocianúrico (ATCI): aspectos computacionais sobre a reatividade e regiosseletividade
We present in this educational article a theoretical analysis based on DFT/B3LYP 6-311++G (d,p) and ab initio MP2/6-311++G(d,p) computational calculation about the reactivity and the regioselectivity on the chlorination reaction of anisole, toluene and nitrobenzene, using trichloroisocyanuric acid (TICA) as donor of Cl+. The H.O.M.O. / L.U.M.O. energy and N.
Química Nova. Publicado em: 2009
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7. Acilenaminonas: Síntese e Aplicação na Obtenção de Pirazóis, Pirazolo[3,4-d]piridazinonas e Pirazolo[1,5-a]pirimidinas / Acylenaminones: Synthesis and Application in the Obtaining of Pyrazoles, Pyrazolo[3,4-d]pyridazinones and Pyrazolo[1,5-a]pyrimidines
The regioespecific synthesis of a series of 14 N-acylated enaminones (52-88%) from the acylation reaction of secondary -enamino ketones [RC(O)CH=CHNR1R2; R = Ph, 4- FC6H4, 4-NO2C6H4, thien-2-yl, CCl3, CF3; R1 = H; R2 = Bn, Ph, 4-NO2C6H4] with trifluoroacetic anhydride or ethyl oxalyl chloride in pyridine is reported. On the other hand, when tertiary enaminon
Publicado em: 2009
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8. Uma metodologia simples e eficiente para a cloração de compostos aromáticos ativados utilizando o ácido tricloro-isocianúrico
The chlorination of activated aromatic rings is efficiently achieved under mild conditions by reaction of aromatic compounds with trichloroisocyanuric acid in acetonitrile, at room temperature, leading to products in 60-95% isolated yields and good regioselectivity.
Química Nova. Publicado em: 2008
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9. Estrutura eletronica de precursores de alomelaninas / Electronic structure of allomelanins precursors
In this work we studied, on the basis of a semiempirical and ab initio approaches, the structure and electronic properties of some allomelanins precursors. Allomelanins are part of an ubiquitous class of dark pigments known as melanins and their precursors are formed by monomers of catechol and o-benzoquinone units. Due to the lack of extensive experimental
Publicado em: 2008
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10. Estudos mecanisticos e metodologicos da reação de Heck entre sais de arenodiazonio e enoleteres, enamidas e enecarbamatos aciclicos. Estudo metodologico da reação de ions N-aciliminio e fenil-[1,3,2]-dioxaborolano / Methodological and mechanistic studies of the reaction of the Heck between arenediazonium salts and acyclic enolethers, enamides and enecarbamates. Methodological study of the reaction between N-acyliminium ions and phenyl-[1,3,2]-dioxaboronates
A reação entre n-butilviniléter e vários sais de arenodiazônio mediada por paládio (0) foi metodologicamente investigada neste trabalho. O sistema catalítico empregado baseou-se naquele descrito por T. Matsuda e colaboradores onde a fonte de paládio é o complexo Pd2dba3.dba, acetonitrila é o solvente e acetato de sódio atua como base. As reações
Publicado em: 2008
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11. Síntese, caracterização e aplicação de catalisadores metaloporfirínicos suportados em MCM - 41
Metalloporphyrin catalysts are well known for their ability to carry out selective oxidation of organic substracts with many oxidizing agents. The current trend in the research is ancor active metalloporphyrins species on solid support, in order to achieve a better recover and reuse of these materials. Besides to prevent the formation of inactive dimmers and
Publicado em: 2006
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12. Structure and electronic properties of alkylthiophenes coupled by Head-to-Tail and Head-to-Head regioselectivity
No presente artigo, métodos teóricos foram utilizados na análise da estrutura e propriedades eletrônicas de oligômeros de alquiltiofenos considerando diferentes regiosseletividades. A lacuna de energia entre as bandas de valência e condução foi calculada nos níveis ab initio Hartree-Fock (HF) e teoria do funcional de densidade (DFT) e semi-empírico
Journal of the Brazilian Chemical Society. Publicado em: 2004-12