In this work, N-alkylated sulfamic acid derivatives are introduced as promising acidic organocatalysts with convenient acidity and easy synthesis. The new organocatalysts derived from different nitrogenated compounds (amines, chitosan, urea and thiourea) were applied in multicomponent reactions to synthesize several dihydropyrimidinones (DHPMs). All tested organocatalysts resulted in good DHPM yields, using classic 1,3-dicarbonyl compounds and long-chain 1,3-dicarbonyl derivatives, demonstrating catalytic efficiency. N-Alkylated sulfamic acid derived from benzylamine showed good results (ca. 80% yields). In addition, excellent results were obtained with organocatalysts based on sulfamic acid and thiourea (ca. 80-97% yields), demonstrating the catalytic efficiency of new derivatives of thiourea organosulfamic catalysts.

A new approach based on multicomponent/domino combined reactions for the synthesis of γ-nitroesters promoted by a mixed aluminium-magnesium oxides derived from hydrotalcite-like material was developed. Different γ-nitroesters were synthesized in 15-95% yield using Meldrum's acid, aromatic aldehydes, nitromethane and different alcohols as reagents and solvents. The γ-aminobutyric acid derivatives, Phenibut and Baclofen, were prepared in 63 and 61% overall yield, respectively, through a two steps synthetic strategy. A mechanistic pathway was proposed based on the gas chromatography mass spectrometry (GC-MS) and electrospray ionization mass spectrometry (ESI-MS) experiments.

Uma série de nove hidratos de cloretos metálicos (ZnCl2.2H2O, SnCl2.2H2O, CdCl2.2H2O, MnCl2.4H2O, CoCl2.6H2O, SrCl2.6H2O, NiCl2.6H2O, CrCl3.6H2O e CeCl3.7H2O) foi investigada como catalisadores ácidos de Lewis brandos e baratos na síntese multicomponente de triarilimidazóis. O melhor catalisador para as reações com benzila foi o SnCl2.2H2O, enquanto que para as reações com benzoína, o CeCl3.7H2O foi mais eficiente. Todas as reações foram efetuadas em EtOH como solvente. Estes catalisadores também foram empregados igualmente com sucesso na síntese de triariloxazóis.

A series of nine metal chloride hydrates (ZnCl2.2H2O, SnCl2.2H2O, CdCl2.2H2O, MnCl2.4H2O, CoCl2.6H2O, SrCl2.6H2O, NiCl2.6H2O, CrCl3.6H2O and CeCl3.7H2O) was investigated as mild and inexpensive Lewis acid catalysts to promote the multicomponent synthesis of triarylimidazoles. Reactions starting from benzil showed the best results when SnCl2.2H2O was used, while for benzoin as the starting material, CeCl3.7H2O was more efficient. All reactions were performed in EtOH as solvent. These catalysts were also successfully employed in the synthesis of triaryloxazoles.

Duas séries de 4-aril-3,4-diidropirimidin-2(1H)-(tio)onas incluindo monastrol (1a), foram sintetizadas por uma metodologia não agressiva ao meio ambiente baseada no uso combinado de ácido cítrico ou ácido oxálico na presença de TEOF (ortoformato de trietila). A atividade como inibidores da proliferação celular da quimioteca de compostos foi avaliada em duas linhagens de gliomas (U138-MG-humana e C6-rato). Os compostos derivados da tiouréia 1f e 1d mostraram atividade citotóxica maior do que a do monastrol. O composto derivado da uréia 2d apresentou a maior atividade citotóxica dentre todos os compostos analisados.

Two series of 4-aryl-3,4-dihydropyrimidin-2(1H)-(thio)ones including monastrol (1a), have been synthesized by an environment-friendly methodology based on the combined use of citric acid or oxalic acid and TEOF (triethylorthoformate). The library was evaluated as inhibitor of cell proliferation on two glioma cell lines (human-U138-MG and Rat-C6). The compounds derived from thiourea 1f and 1d were more cytotoxic than monastrol. The compound derived from urea 2d showed the highest cytotoxic activity among the analyzed compounds.

O uso de haletos metálicos hidratados, tais como, SnCl2·2H2O, MnCl2·4H2O, SrCl2·6H2O, CrCl2·6H2O, CoCl2·6H2O e CeCl3·7H2O como catalisadores ácidos de Lewis foi investigado nas reações conjugadas tipo Friedel-Crafts entre indóis e olefinas ativadas. A utilização de enonas alifáticas forneceu as respectivas β-indolilcetonas à temperatura ambiente em longos tempos de reação, enquanto que nas reações com chalconas foi necessário o uso de condições de refluxo em isopropanol. As reações dos indóis com nitroestirenos foram efetuadas tanto em fase líquida como em condições sem solvente. Em todos os casos estudados foram obtidos rendimentos de razoáveis a bons.

Metal halide hydrates such as SnCl2·2H2O, MnCl2·4H2O, SrCl2·6H2O, CrCl2·6H2O, CoCl2·6H2O e CeCl3·7H2O were investigated as mild Lewis acids catalysts for the conjugate Friedel-Crafts reaction between indoles and activated olefins. The reactions were carried out with aliphatic unsaturated ketones over a period of days at room temperature, while chalcones reacted only under reflux conditions. The reactions with nitrostyrenes were either performed in solvent or under solventless conditions. In all cases reasonable to good yields were obtained.

Nesse trabalho estudou-se a reação de ciclodesidratação entre antranilonitrila e várias cetonas na presença de diferentes ácidos de Lewis não reportados na literatura, para a obtenção de 9-amino-1,2,3,4-tetrahidroacridinas. As reações de ciclodesidratação foram realizadas em condições térmicas empregando-se diferentes solventes e também na ausência de solvente, seguidas de hidrólise alcalina, levando à obtenção dos produtos em bons a excelentes rendimentos após isolamento.

The scope of Lewis acid-promoted cyclodehydratation reactions between anthranilonitrile and several ketones, to afford tacrine and its derivatives, was expanded to include the use of various metal chloride salts not reported in the literature. The ability of the Lewis acids to effectively promote the cyclodehydratation between anthranilonitrile and cyclohexanone as the ketone was found to be the following order: InCl3 > AlCl3 ~ BF3.Et2O > FeCl3 > BiCl3 ~ SbCl3 ~ SnCl2.2H2O. The reactions were performed under both solvent and solvent-free conditions in good to excellent yields. Other Lewis acids screened, such as RuCl3, CeCl3, NiCl2, CoCl2.2H2O and CsCl were not effective.

In this paper, we describe a practical route for the synthesis of Biginelli compounds using In(OTf)3. To study the generality of this catalyst, several examples using aromatic aldehydes, 1,3-dicarbonyl compounds, urea, and thiourea were investigated. The present procedure provides an efficient modification of the classical Biginelli reaction, namely short reaction times and simple work-up, that not only preserves the simplicity of the original protocol but also produces excellent yields of 3,4-dihydropyridin-2(1H)-ones. Thiourea was used with similar success to provide the corresponding 3,4-dihydropyridin-2(1H)-thiones. In this case, the (+/-)-monastrol, antimitotic agent, was obtained in 92% yield and new thio analogues were synthesized.

A adição nucleofílica de vários nucleófilos (alilsilano, silil enol éter da acetofenona, indol e N-sulfonilindol) ao íon N-acilimínio enantiopuro 1a, derivado do ácido (S)-málico, promovida por pentacloreto de nióbio é descrita. Os produtos foram obtidos em bons rendimentos e em diastereosseletividades variáveis dependendo do volume estérico do nucleófilo. Os melhores resultados foram obtidos com a adição de indóis.

The nucleophilic addition of several nucleophiles (allyltrimethylsilane, silyl enol ether from acetophenone, indole and N-sulfonylindole) to the enantiopure cyclic N-acyliminium ion 1a, derived from (S)-malic acid, promoted by niobium pentachloride is described. The products were obtained in good yields and in variable diastereoselectivities depending on the steric bulkiness of the nucleophile. The best results were obtained with the addition of indoles.

Neste trabalho é descrita a habilidade do SnCl2.2H2O como catalisador na reação de Biginelli tricomponente. Uma variedade de aldeídos aromáticos mono- e dissubstituidos foi utilizada na condensação com acetoacetato de etila e uréia ou tiouréia. A reação foi efetuada em etanol ou acetonitrila como solventes em meio neutro e os resultados representam um melhoramento com relação ao procedimento clássico de Biginelli e uma vantagem com relação ao uso de FeCl3.6H2O, NiCl2.6H2O e CoCl2.6H2O que são utilizados juntamente com HCl como co-catalisador. A síntese das 3,4-diidropirimidinonas foi conseguida em bons rendimentos.

The ability of SnCl2.2H2O as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea is described. The reaction was carried out in acetonitrile or ethanol as solvents in neutral media and represents an improvement of the classical Biginelli protocol and an advantage in comparison with FeCl3.6H2O, NiCl2.6H2O and CoCl2.6H2O which were used with HCl as co-catalyst. The synthesis of 3,4-dihydropyrimidinones was achieved in good to excelent yields.