%0 Journal Article
%T A convenient synthesis of 3-aryl-1,2,4-oxadiazoles from ethyl acetoacetate and amidoximes under solvent-free conditions Uma s赤ntese conveniente de 3-aril-1,2,4-oxadiaz車is a partir do acetoacetato de etila e amidoximas na aus那ncia de solvente
%A Juliana L. L. F. Regueira
%A Joˋo R. de Freitas Filho
%J Orbital : the Electronic Journal of Chemistry
%D 2012
%I Universidade Federal de Mato Grosso do Sul
%X 1,2,4-Oxadiazole containing compounds have attracted great attention due to their applications in material chemistry and therapeutics. Herein we report a convenient synthesis of 3-aril-[1,2,4-oxadiazol-5yl] propan-2-one (3a-d) by heating of b-ceto esters and an amidoximes without any solvent and in the absence of base. The arylamidoximes (1a-f) was synthesized in moderate and excellent yields (31- 89%) by reaction of nitrile with hydroxylamine hydrochloride in water at 25oC. In the general synthetic strategy employed in our study is illustrated in scheme 1. The 3-aril-[1,2,4-oxadiazol-5yl] propan-2-one (3a-f) were synthesized by treatment of arylamidoxime (1a-f with b-ceto esters for 4 hour without any solvent and in the absence of base. The reaction was monitored  by TLC   (thin layer chromatography). The heterocycles (3a-f) were obtained in moderate and good yields (60-88%). The products were identified using both analytical and spectral data (IR, 1H and 13C NMR) and all compounds are in full agreement with the proposed structure. Os 1,2,4-oxadiaz車is s o compostos que t那m atra赤do grande aten  o devido 角s suas aplica  es em qu赤mica de materiais e terap那utica. Descrevemos aqui uma s赤ntese conveniente de 3-aril-[1,2,4-oxadiazol-5il]-propan-2-ona (3a-d) por aquecimento de um b-ceto 谷ster e amidoximas na aus那ncia de  solvente e de base. As arilamidoximas (1a-f) foram sintetizadas em rendimentos moderados e excelentes (31 - 89%) pela rea  o de nitrilas com Cloridrato de Hidroxilamina em 芍gua a 25 o C. A estrat谷gia geral de s赤ntese empregada em nosso estudo 谷 ilustrada no esquema 1. Os 3-aril-[1,2,4-oxadiazol-5-il] propan-2-ona (3a-f) foram sintetizados pelo tratamento de arilamidoximas (1a-f ) com b-ceto 谷ster (2) por 4 horas, sem qualquer solvente e na aus那ncia de base. A rea  o foi monitorada por TLC (cromatografia de camada fina). Os heterociclos (3a-f) foram obtidos com rendimentos moderados e bons (60-88%). As estruturas dos produtos foram elucidadas usando os dados espectrosc車picos (IV, RMN 1H e RMN 13C) e todos os compostos est o em concordancia com a estrutura proposta.
%K amidoxima
%K 1
%K 2
%K 4-oxadiaz車is
%K sem solvente
%U http://www.orbital.ufms.br/index.php/Chemistry/article/view/344