Niobium Pentachloride Catalyzed Multicomponent Povarov Reaction

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efficient one-pot synthesis of 14-aryl-14H-dibenzo [a,j]xanthene derivatives promoted by niobium pentachloride

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chemoselective condensationof beta-naphthol, dimethyl malonate, andaromatic aldehydes promoted by niobium pentachloride

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synthesis of Quinoline Derivatives by Multicomponent Reaction Using Niobium Pentachloride as Lewis Acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Niobium pentachloride promoted synthesis of tetrahydropiridines by multicomponent reaction

One-pot multicomponent synthesis of tetrahydropyridine derivatives between aniline derivatives, benzaldehyde and two different β-keto ester (methyl and ethyl acetoacetate) using niobium pentachloride as catalyst under mild conditions, providing good yields.

Chemoselective condensation of β-naphthol, dimethyl malonate, and aromatic aldehydes promoted by niobium pentachloride

A multicomponent reaction of β-naphthol, dimethyl malonate, and aromatic aldehydes in the presence of NbCl5 as promoter is described. Under similar conditions, aromatic aldehydes with different substituents exhibited different behaviors than β-naphthol and dimethyl malonate. In these MCRs, 4-aryl-3,4-dihydrobenzo[f]coumarins are obtained as the major products (41–93%) and 14-aryl-14H-dibenzo[a,j]xanthenes as the minor products (1–38%).

NbCl5-Promoted Synthesis of 4-Aryl-3,4-dihydrocoumarins by Multicomponent Reaction

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudos sobre a síntese de piperidinas funcionalizadas através de reações pentacomponentes, utilizando compostos de nióbio como catalisadores

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Preparação e caracterização estrutural de complexos quirais de nióbio, utilizando álcoois terpênicos quirais como ligantes

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Estudo sobre o uso do pentacloreto de nióbio em reações multicomponentes para síntese de derivados de 4-ARIL-3,4-DI-Hidrocumarinas

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Síntese de derivados 4-aril-3,4-di-hidrocumarínicos catalisada por NbCl5

Multicomponent reactions between phenols, β-diesters and benzaldehydes for the synthesis of 4-aryl-3,4-dihydrocoumarin derivatives were carried out under mild conditions (room temperature) and presented moderate yields (38-88%) and reasonable reaction times (2-4 days), using niobium pentachloride as a catalyst.

Estudo sobre o uso do pentacloreto de nióbio, como ácido de Lewis, na síntese de enaminas através da reação de adição de Michael

The NbCl5 being a strong electrophile, is a potential candidate to act as a Lewis acid, and therefore it mediates various organic reactions. For this reason, it has received continuous attention by Brazilian researchers, especially in recent decades, since Brazil holds the largest reserves of niobium, besides being the largest producer of this element. The Michael addition reaction is one of the most widely used for forming carbon-carbon bonds and takes place by the addition of nucleophiles to activated olefins. Although this type of reaction is usually catalyzed by base, there are reports in the literature on the use of various Lewis acids in this type of reaction. The synthesis of enamines based acetilenodicarboxilates and amines, aromatic or alkyl, by Michael addition reaction is quite interesting, since these are valuable synthetic intermediates for the synthesis of heterocyclic and they are used in multicomponent reactions. The derivatives of anilino-fumarate also have a great potential for medical application. In this study we investigated the use of niobium pentachloride as Lewis acid to catalyze the Michael additions between the derivatives of aniline and acetilenodicarboxilates the synthesis of enamines

Síntese de 14-aril-14h-dibenzol[a,j]xantenos e 4-aril-3,4-di-hidrobenzo[f]cumarinas promovida pelo pentacloreto de nióbio, com potencial aplicação na preparação de corantes sensibilizadores para utilização em dispositivos de Grätzel

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudos sobre a aplicação do pentacloreto de nióbio na síntese de derivados de 4-aril-3,4-di- hidrocumarinas

Coumarin is a natural active compound that can be found in many plants. The coumarins have many properties such as bronchodilator, anti-inflammatory, antioxidant, anticoagulant, antibiotics, immunomodulatory, antimicrobial and antiviral, thus, they are widely used in medical applications. More recently the coumarin derivatives have attracted the interest of many research groups in the field of new materials, for example the possibility of their use as sensitizers in dye-sensitized solar cells (DSSC) and lasers. The MCRs are defined as a process in which three or more reactants are combined in the same reaction pot, resulting in products with good structural complexity a single step, in addition to economy of atoms and selectivity and is a very important feature in modern synthetic methodology. In this work we investigated the use of niobium pentachloride as catalyst of the multicomponent reactions between phenolic derivatives, various aromatic aldehydes and β-diester derivatives in the synthesis of 4-aryl-3,4-dihydrocoumarin derivatives. The reactions were carried out at room temperature, under inert atmosphere (N2), using dichloromethane anhydrous (CH2 Cl2) as solvent, with a reaction time of most 120 hours. The products were isolated by column chromatography on silica gel and submitted to spectrometric and spectroscopic analysis. The results show that NbCl5 is an excellent agent for promoting the synthesis of 4-aryl-3,4-dihydrocoumarin derivatives through multicomponent reactions, obtaining yields varying from 45 to 95%

Estudos sobre o uso de NbCl5 como ácido de Lewis em reações de Povarov

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)