Abstract:R.M. Sri vas ta va*, and G.M. Se a bra
De par ta men to de Qu í mi ca Fun da men tal, Uni ver si da de Fe de ral de Per nam bu co, Ci da de Uni ver si tá ria, 50.670-901 Re ci fe -PE, Bra zilRe ce i ved: Octo ber 28, 1996 Nes te ar ti go des cre ve mos as sín te ses dos áci dos 3-[3-(aril)-1,2,4-oxadiazol-5-il] pro piô nicos 3a-g , com alto ren di men to, a par tir das ari la mi do xi mas 1a-g e do ani dri do suc cí ni co. Os 1,2,4-oxadiazóis 3a-f tam bém fo ram ob ti dos fa zen do-se a re a ção em um for n… Show more
“…We observed a relationship between LC 50 values and substituent electronegativity properties: LC 50 F 3eϾLC 50 Cl 3fϾLC 50 Br 3g. Halogenated compounds 3g (LC 50 ϭ15.2 ppm) and 3f (LC 50 ϭ28.1 ppm) may be considered highly active (LC 50 values Ͻ50 ppm) and these LC 50 values are similar to the activity of essential oils obtained from the leaf, stem and inflorescence of Piper marginatum (LC 50 ϭ19.9-23.8 ppm) 42) as well as the leaf of Cryptomeria japonica D. DON (LC 50 ϭ37.6 ppm). 45) Moreover the best LC 50 values for 1,2,4-oxadiazole are comparable to the larvicidal effect of b-asarone, natural botanical insecticide, which have exhibited an LC 100 of 16 ppm.…”
Section: Resultsmentioning
confidence: 95%
“…As reported in the literature, the above-cited acids were obtained in good yields in 10 min. 42) Since these compounds are gaining more and more significance, we decided to improve their microwave-accelerated synthesis under solventless conditions. With this aim, we performed a few experiments using a specific focused microwave oven.…”
Section: Resultsmentioning
confidence: 99%
“…In order to get the best yield of these acids, we have chromatographed the crude mixture over silica gel. This way the yield was excellent, 41,42) but this procedure is expensive and time-consuming. In this work we isolated compounds 4a-i and 5a-i, respectively.…”
Section: Resultsmentioning
confidence: 99%
“…41) Later, these reagents were heated in a household microwave oven under solvent-free conditions for 10 min 42) with better yields in comparison with the solution method. It is now well established that focused microwave reactors are quite superior to the domestic ones due to their ability of focusing energy on the sample producing a faster heating of the reagents.…”
Section: )mentioning
confidence: 99%
“…41,42) The crude product was dissolved in ethyl acetate (30 ml), then a concentrated aqueous solution of NaHCO 3 (35 ml) was added to it, and the mixture was stirred overnight. The aqueous layer was separated followed by the addition of concentrated aqueous citric acid solution until total precipitation of the desired compound 3a-i occurred.…”
The synthesis of 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids from arylamidoximes and succinic anhydride under focused microwave irradiation conditions is described. The new synthetic method furnished the desired products in 2-3 min and good yields. Furthermore, the previously complicated purification procedure has been simplified in a manner which is quick, eco-friendly and cost-effective. Larvicidal bioassay and fungal growth inhibitory tests were performed using several 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids. These acids presented strong larvicidal activity against L4 larvae of Aedes aegypti. The results suggest that larvicidal activity might be correlated with the presence of electron-withdrawing substituents in the para position of the phenyl ring except the fluorine atom. The alterations observed in the larvae spiracular valves of the siphon and anal papillae by 1,2,4-oxadiazoles in the larvicidal bioassay are responsible for larvae's death. Furthermore, all acids inhibited the fungal growth of five different types of fungi, viz., Fusarium solani, F. oxysporum, F. moniliforme, F. decemcellulare and F. lateritium in a preliminary evaluation. Both of these activities are being disclosed for the first time for 1,2,4-oxadiazole-5-yl ring linked at C-3 of propionic acid.
“…We observed a relationship between LC 50 values and substituent electronegativity properties: LC 50 F 3eϾLC 50 Cl 3fϾLC 50 Br 3g. Halogenated compounds 3g (LC 50 ϭ15.2 ppm) and 3f (LC 50 ϭ28.1 ppm) may be considered highly active (LC 50 values Ͻ50 ppm) and these LC 50 values are similar to the activity of essential oils obtained from the leaf, stem and inflorescence of Piper marginatum (LC 50 ϭ19.9-23.8 ppm) 42) as well as the leaf of Cryptomeria japonica D. DON (LC 50 ϭ37.6 ppm). 45) Moreover the best LC 50 values for 1,2,4-oxadiazole are comparable to the larvicidal effect of b-asarone, natural botanical insecticide, which have exhibited an LC 100 of 16 ppm.…”
Section: Resultsmentioning
confidence: 95%
“…As reported in the literature, the above-cited acids were obtained in good yields in 10 min. 42) Since these compounds are gaining more and more significance, we decided to improve their microwave-accelerated synthesis under solventless conditions. With this aim, we performed a few experiments using a specific focused microwave oven.…”
Section: Resultsmentioning
confidence: 99%
“…In order to get the best yield of these acids, we have chromatographed the crude mixture over silica gel. This way the yield was excellent, 41,42) but this procedure is expensive and time-consuming. In this work we isolated compounds 4a-i and 5a-i, respectively.…”
Section: Resultsmentioning
confidence: 99%
“…41) Later, these reagents were heated in a household microwave oven under solvent-free conditions for 10 min 42) with better yields in comparison with the solution method. It is now well established that focused microwave reactors are quite superior to the domestic ones due to their ability of focusing energy on the sample producing a faster heating of the reagents.…”
Section: )mentioning
confidence: 99%
“…41,42) The crude product was dissolved in ethyl acetate (30 ml), then a concentrated aqueous solution of NaHCO 3 (35 ml) was added to it, and the mixture was stirred overnight. The aqueous layer was separated followed by the addition of concentrated aqueous citric acid solution until total precipitation of the desired compound 3a-i occurred.…”
The synthesis of 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids from arylamidoximes and succinic anhydride under focused microwave irradiation conditions is described. The new synthetic method furnished the desired products in 2-3 min and good yields. Furthermore, the previously complicated purification procedure has been simplified in a manner which is quick, eco-friendly and cost-effective. Larvicidal bioassay and fungal growth inhibitory tests were performed using several 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids. These acids presented strong larvicidal activity against L4 larvae of Aedes aegypti. The results suggest that larvicidal activity might be correlated with the presence of electron-withdrawing substituents in the para position of the phenyl ring except the fluorine atom. The alterations observed in the larvae spiracular valves of the siphon and anal papillae by 1,2,4-oxadiazoles in the larvicidal bioassay are responsible for larvae's death. Furthermore, all acids inhibited the fungal growth of five different types of fungi, viz., Fusarium solani, F. oxysporum, F. moniliforme, F. decemcellulare and F. lateritium in a preliminary evaluation. Both of these activities are being disclosed for the first time for 1,2,4-oxadiazole-5-yl ring linked at C-3 of propionic acid.
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