Síntese e fitotoxicidade de benzopironas análogas ao alternariol

• Autor(a) principal: Silva, Cleiton Moreira da
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2080
• topic: Alternariol; Micotoxina; Benzopironas; Herbicidas; Alternariol; Mycotoxins; Benzopyrones; Herbicides; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

Fungi of the genus Alternaria are known to cause foliar injury in a variety of plants. Studies show that alternariol, a secondary metabolite produced by these microorganisms may be directly related to its phytotoxicity, including on weeds. In this context, this work aimed to synthesize several alternariol analogues as well as evaluate the phytotoxic activity through tests using the reaction of Hill. The synthetic route used in the synthesis of these compounds was initially in a cross- coupling reaction between aromatic aldehydes halogenated in the ortho position and phenylboronics acids metoxilated in the ortho position in the presence of a palladium catalyst (Suzuki s coupling). The resulting biaryls had the aldehyde group oxidized in the presence of sodium chlorite (NaClO2) generating the respective carboxylic acids. These acids were subjected to a step of deprotection of methoxyl groups and subsequent formation of a lactone ring in the presence of boron tribromide (BBr3) or iodidric acid (HI), giving rise to the following alternariol analogues: 2-methyl-6H-benzo-[c] chromen-6-one [17], 7-fluoro-2-methyl-6H-benzo[c] chromen-6-one [18], 2-chloro-6Hbenzo[c]chromen-6-one [19], 9-fluoro-5H-chromene[4,3-b]pyridin-5-one [20], 9- methyl-5H-chromene[4,3-b]pyridin-5-one [21], 7-bromo-9- fluoro-5Hchromene[4,3-b]pyridin-5-one [22] and 7-bromo-9- fluoro-5H-chromene[4,3-c]pyridin-5-one [23]. Five analogues were subjected to in vitro tests, looking for evaluate their activities on the electron transport chain through the reaction of Hill. Results from these tests showed that the compounds tested (17 - 21) presented moderate activity, and the compound 19 the most active, with the ID50 value equal to 435 ± 60 μM.