Síntese e avaliação da atividade fitotóxica de 8- oxabiciclo[3.2.1]oct-6-en-3-ona substituídos e de ozonídeos derivados

• Autor(a) principal: Pereira, Ulisses Alves
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2048
• topic: Ozonídeos; Síntese; Atividade fitotóxica; Ozonides; Synthesis; Phytotoxic activity; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA

Artemisinin is a sesquiterpene lactone isolated from the leaves of Artemisia annua L. It has been demonstrated that this lactone exhibits phytotoxic activity against various monocotyledonous and dicotyledonous species. The observed biological activity has been associated with the presence of the endoperoxide moiety in the structure of this compound. In the present investigation, a series of ozonides, possessing the endoperoxide moiety, was synthesized and evaluate in terms of their phytotoxic activities. The ozonides were prepared from the 8-oxabicyclo[3.2.1]oct-6-en-3-one derivates, which were obtained via [4+3] cycloaddition between oxyallyl carbocation and pertinent furans. The carbocation, in turns, was generated in situ from the 2,4-dibromopentan-3-one. Nine ozonides were obtained namely: 2,3-exo,5-exo-6- tetramethyl-8,9,10,11-tetraoxatricyclo[5.2.1.12,6]undecan- 4-one (100%), 2,3-exo,5-exo-trimethyl-8,9,10,11- tetraoxatricyclo[5.2.1.12,6]undecan-4-one (100%), 1,2,3- exo,5-exo-tetramethyl-8,9,10,11-tetraoxatricyclo[5.2.1.12,6]undecan-4-one (7%), 2-acetyl-3-exo,5-exo-dimethyl- 8,9,10,11-tetraoxatricyclo[5.2.1.12,6] undecan-4-one (98%), 2-ethyl,3-exo,5-exo-dimethyl-8,9,10,11-tetraoxatricyclo [5.2.1.12,6]undecan-4-one (100%), 3-exo,5-exo-dimethyl- 8,9,10,11-tetraoxatricyclo[5.2.1.12,6]undecan-4-one (99%), 2,3-exo,5-exo-trimethyl-1-(methoxycarbonyl)-8,9,10,11- tetraoxatricyclo[5.2.1.12,6]undecan-4-one (50%), 1-hydroxymethyl-2,3-exo,5-exo-trimethyl-8,9,10,11- tetraoxatricyclo[5.2.1.12,6] undecan-4-one (75%), 2,3-exo, 5-exo-trimethyl-1-(methoxymethyl)-8,9,10,11- tetraoxatricyclo[5.2.1.12,6]undecan-4-one (100%). The phytotoxic activity of the synthesized ozonides as well as the 8-oxabicyclo[3.2.1]oct-6-en-3-one derivates, was evaluated against sorghum (Sorghum bicolor L.) and cucumber (Cucumis sativus L.), at 7.5 x 10-4 mol L-1 and 7.5 x 10-5 mol L-1. Among the oxabicyclos, the most phytotoxic substance was 7-(methoxycarbonyl)-1,2α,4α-trimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one, inhibiting the root growth of cucumber and sorghum by 34.3% and 53.0%, respectively, at 7.5 x 10-4 mol L-1. Concerning the ozonides, the best result was achieved with compound 2,3-exo,5-exo-6-tetramethyl-8,9,10,11- tetraoxatricyclo[5.2.1.12,6]undecan-4-one which inhibited root growth of sorghum by 48.3% at 7.5 x 10-4 mol L-1.