The worldwide emergence of viral diseases such as Zika, Dengue, Chikungunya, West Nile and Yellow Fever urge the search for solutions to eliminate their common vector, the Aedes aegypti mosquito. This paper describes the quantitative structure-activity relationship (QSAR) and docking studies of a series of nine 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids (AOPA), 1-9, previously published by our group. Additionally, three new 1,2,4-oxadiazoles, 10-12, have also been synthesized, characterized and studied. The QSAR and docking studies of all compounds, 1-12, clearly indicate that larger hydrophobic substituents such as biphenyl groups attached on position 3 in 1,2,4-oxadiazoles improve the larvicidal activity. It is worthwhile to mention that nanocapsulation of compounds 10-12 were necessary to help their dissolution in water and these three new 1,2,4-oxadiazoles also exhibited approximately equal or higher larvicidal activities compared to the former prototypes at stage L4.

Uma síntese limpa, fácil e eficiente de vários 1,2,4-oxadiazóis 3,5-dissubstituídos partindo de um anidrido misto (gerado a partir de um ácido carboxílico e cloroformiato de etila) e amidoxima é descrita.

An efficient, clean and easy high-yielding synthesis of 3,5-disubstituted 1,2,4-oxadiazoles starting from mixed anhydrides (generated from carboxylic acids and ethyl chloroformate) and arylamidoximes is described.

Uma síntese fácil, eficiente e rápida de N-benzoil-(e benzoil N-substituída)-N,N'-dialquiluréias foi realizada com bons rendimentos em condições livre de solvente. Primeiramente, a reação entre um ácido carboxílico e uma carbodiimida dissubstituída foi feita empregando radiação de microondas, e depois a mesma reação foi realizada sob aquecimento convencional. Os rendimentos são comparáveis em ambos os casos.

An easy, efficient and quick synthesis of N-benzoyl-(and N-substituted benzoyl)-N,N'dialkylureas, in good yields, under solvent-free conditions is described. First, the reaction between a carboxylic acid and a disubstituted carbodiimide was carried out employing microwave radiation, and later on the same reaction was performed separately under dry heating without any radiation. The yields are comparable in both cases.

Uma síntese eficiente e fácil dos compostos: 2-fenillaminometil-isoindol-1,3-diona (5a), 2-[(2-Clorofenilamino)metil]-isoindol-1,3-diona (5b), 2-[(3-Clorofenilamino)methyl]-isoindol-1,3-diona (5c), 2-[(4-Clorofenilamino)metil)-isoindol-1,3-diona (5d), 2-[(2-Flúorfenilamino)metil]-isoindol-1,3-diona (5e), 2-[(3-flúorfenilamino)metil]-isoindol-1,3-diona (5f), 2-[(4-Flúorfenilamino)metil]-isoindol-1,3-diona (5g), 2-[(2-Nitrofenilamino)metil]-isoindol-1,3-diona (5h), 2-[(3-Nitrofenilamino)metil]-isoindol-1,3-diona (5i), 2-[(4-Nitrofenilamino)metil]-isoindol-1,3-diona (5j), 2-[1H-(1,2,4)Triazol-3-il-aminometil)-isoindol-1,3-diona (5k) e 2-([1,2,4]-Triazol-4-il-aminometil)-isoindol-1,3-diona (5l) está descrita. A síntese foi realizada partindo-se da N-hidróximetilftalimida 3 e de aril- e [1,2,4-triazol-3- e 4-il]-aminas 4a-l através de procedimentos convencional e mediado por microondas. A reação de 3 com 4l aconteceu rapidamente e com altos rendimentos. Está descrita uma comparação entre estes dois métodos. São propostos três prováveis mecanismos de formação das N-(arilaminometil)-ftalimidas (um em solução e os outros dois em condições de aceleração por microondas). As análises cristalográficas de 5d forneceram as informações apropiadas sobre a conformação da mesma. Cálculos de orbitais moleculares Ab initio de 5d empregando um conjunto de base 6-31G* foi realizado e os resultados concordaram com os dados de raio-X.

An efficient and easy synthesis of compounds: 2-Phenylaminomethyl-isoindole-1,3-dione (5a), 2-[(2-Clorophenylamino)methyl]-isoindole-1,3-dione (5b), 2-[(3-Clorophenylamino)methyl]-isoindole-1,3-dione (5c), 2-[(4-Clorophenylamino)methyl)-isoindole-1,3-dione (5d), 2-[(2-Fluorophenylamino)methyl]-isoindole-1,3-dione (5e), 2-[(3-fluorophenylamino)methyl]-isoindole-1,3-dione (5f), 2-[(4-Fluorophenylamino)methyl]-isoindole-1,3-dione (5g), 2-[(2-Nitrophenylamino)methyl]-isoindole-1,3-dione (5h), 2-[(3-Nitrophenylamino)methyl]-isoindole-1,3-dione (5i), 2-[(4-Nitrophenylamino)methyl]-isoindole-1,3-dione (5j), 2-[1H-(1,2,4)Triazol-3-yl-aminomethyl)-isoindole-1,3-dione (5k) and 2-([1,2,4]-Triazole-4-yl-aminomethyl)-isoindole-1,3-dione (5l), is described. The general synthesis procedure starts from N-hydroxymethylphthalimide 3 and aryl- and [1,2,4-triazol-3- and 4-yl]-amines 4a-l by conventional and solvent-free microwave-mediated. The reaction of 3 with 4l turned out to be a very rapid and high-yielding one. A comparison of these two methods has been made. Three probable mechanisms of formation of N-(arylaminomethyl)-phthalimides (one in the solution phase and two in the microwave-accelerated conditions are proposed. Crystallographic analyses of 5d furnished the correct conformation of this molecule. Ab initio molecular orbital calculations of 5d using 6-31G* basis set were performed and the results were comparable to the X-ray data.

The present contribution describes three different modern experiments for possible adoption in undergraduate organic chemistry laboratories. These are: 1. electrocatalytic hydrogenation of benzaldehyde to benzyl alcohol; 2. identification of three volatile components, obtained from pineapple fruit, by mass spectrometry and 3. microwave mediated fast synthesis of N-(p-chlorophenyl)phthalamic acid from phthalic anhydride and p-chloroaniline under solvent-free conditions. The experiments can be executed in a short period of time, putting the undergraduate student in contact with a variety of topics in organic chemistry and several techniques of analysis, showing multidisciplinarity in organic chemistry.

Uma fácil e eficiente síntese para obtenção de beta-aminocetonas 5a, 6 e gama-aminoálcoois 1a, 2a, 3, 4 enantiomericamente puros a partir de L-prolinol 7 e L-prolina 15 é descrita. A etapa principal da reação foi o uso do reagente de Tebbe que permitiu a transformação da função éster a um enol éter que após hidrólise formou a cetona sem nenhuma racemização.

An easy and efficient route for the synthesis of enantiomerically pure beta-aminoketones 5a, 6 and gamma-aminoalcohols 1a, 2a, 3, 4 from L-prolinol 7 and L-proline 15 is described. One of the key steps is the use of Tebbe's reagent allowing the transformation of the ester function to an enol ether without any racemization.

Uma síntese fácil e eficiente de 3-aril-5[(1S)-t-butiloxicarbonil-1-amino-( 2S)-metil-1-butil)]-1,2,4-oxadiazóis 4a-f e 3-fenil-5-[(1S)-t-butiloxicarbonil-1-amino-1-etil]-1,2,4-oxadiazol 6 partindo de arilamidoximas, N-t-Boc-L-isoleucina e N-t-Boc-L-alanina é descrita. As estruturasedos intermediários e compostos finais foram determinadas a partir dos dados espectroscópicos.

A facile and efficient synthesis of 3-aryl-5-[(1S)-t-butyloxycarbonyl-1-amino-(2 S)-methyl-1-butyl)]-1,2,4-oxadiazoles 4a-f and 3-phenyl-5-[(1S)-t-butyloxycarbonyl-1-amino-1-ethyl]-1,2,4 -oxadiazole 6 starting from arylamidoximes, N-t-Boc-L-isoleucine and N-t- Boc-L-alanine is decribed. The structures of the intermediates and final compounds have been deduced from spectroscopic data.

A reação de tri-O-acetil-D-glucal (1) com cicloexanol (2) usando o método de Ferrier forneceu o glicosídeo cicloexílico insaturado 3, que por sua vez produziu o composto 12 através da seqüência envolvendo hidrólise, tritilação seletiva no oxigênio do C-6, oxidação alílica e cicloadição dipolar 1,3 com diazometano. O produto 17 foi obtido em quatro etapas a partir de 6. Cálculos semi-empíricos de orbitais moleculares (AM1) para o composto 12 forneceram a conformação estável e também apoiaram a existência do efeito anomérico. Foi feito um esforço para abrir o anel pirazolínico dos compostos 12 e 17, porém não tivemos sucesso. A carga negativa parcial no C-3 foi responsável pela falta de reatividade deste carbono frente a redução da ligação C=N.

Reaction of tri-O-acetyl-D-glucal (1) with cyclohexanol (2) using Ferrier's method provided the unsaturated cyclohexyl glucoside 3, which furnished the title compound 12 in a sequence involving hydrolysis, selective tritylation of oxygen at C-6, allylic oxidation with MnO2 and 1,3-dipolar cycloaddition with diazomethane. Starting from 6, product 17 was obtained in four steps. Semi-empirical molecular orbital calculations (AM1) were carried out for compound 12 which gave an idea about its stable conformation, and also supported the existence of the anomeric effect. Attempts to open the pyrazoline ring in 12 and 17 failed. Partial negative charge at C-3 was responsible for the lack of reactivity of 12 towards reduction of C=N bond.