Síntese de piretróides e estudo de sua atividade inseticida

• Ano de defesa: 2006
• Autor(a) principal: Carneiro, Vânia Maria Teixeira
• Orientador(a): Alvarenga, Elson Santiago de
• Banca de defesa: Virtuoso, Luciano Sindra , Paula, Vanderlúcia Fonseca de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Piretróides - Síntese; Inseticidas; Química orgânica; Fotoquímica
• Palavras-chave em Inglês: Pyrethroids - Synthesis; Insecticides; Organic Chemistry; Photochemistry
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2177

The term pyrethroid is used to designate synthetic insecticides derived structurally of pyrethrins. Decades of researches done by the industry agrochemistry and for government and academic laboratories have been resulting in a wide change of structure of pyrethroids and in a multiplicity of uses in the agriculture, veterinary and control of domestic plagues. It is known that the prolonged use of agricultural defensives takes the development of resistance mechanisms for several species, besides the toxicant effects caused to the environment. These disadvantages justify the need of search for agricultural chemicals more specific and with larger insecticide action. In that way, the first part of this work had as objective the pyrethroids synthesis containing several aromatic groups in substitution to the group dimethylvinyl presents in the structure of several pyrethroids and pyrethrins. The synthetic route shown in the first chapter used as first material D-mannitol (1.1), that was submitted to a reaction with ketone in presence of zinc chloride, taking the formation of 1,2:5,6-di-O- isopropylidene-D-mannitol (1.2) in 87% of yielding. The diacetal (1.2) was broken with sodium periodate for the formation of 2,3-O-isopropylidene-D-glyceraldehyde (1.3). The aldehyde (1.3) was submitted to the reaction of Wittig being used methoxycarbonyl(triphenyl)phosphonium in methanol for the formation of esters methyl (S)-(Z)-4,5-O-isopropylidenepent-2-enoate (1.4) and methyl (S)-(E)-4,5-O- isopropylidenepent-2-enoate (1.5) (8: 1) in 24% of yielding starting from the diacetal (1.2). The ester (1.4) was used in the synthesis of methyl (1S,3S)-3-[(S)-2,2-dimethyl- 1,3-dioxolan-4-il]-2,2-dimethylcyclopropane-1-carboxylate (1.6) in 50% of yielding, with Wittig salt. The product (1.6) was hydrolyzed with perchloric acid in THF and broken with sodium periodate that resulted the methyl (1S,3S)-3-formil-2,2- dimethylcyclopropane-1-carboxylate (1.7) in 80% of yielding (and 40% of yielding starting from 1.4). The esters (1.5) was submitted to the same sequence of reactions of esters (1.4) taking the formation of methyl (1R,3R)-3-[(R)-2,2-dimethyl-1,3-dioxolan-4- il]-2,2-dimethylcyclopropane-1-carboxylate (1.8) and later on of methyl (1R,3R)-3- formil-2,2-dimethylcyclopropane-1-carboxylate (1.9) in 10% of yielding starting from (1.5). Finally, the pyrethroids methyl (1S,3S)-3-[2-(2-methoxyphenyl)eten-1-il]-2,2- dimethylcyclopropane-1-carboxylate (1.10), methyl methoxyphenyl)eten-1-il]-2,2-dimethylcyclopropane-1-carboxylate (1S,3S)-3-[2-(3- (1.11), methyl (1S,3S)-3-[2-(2-chlorophenyl)eten-1-il]-2,2-dimethylcyclopropane-1-carboxylate (1.12), methyl (1S,3S)-3-[2-(pentafluorophenyl)eten-1-il]-2,2-dimethylcyclopropane-1- carboxylate (1.13) and methyl (1S,3S)-3-[2-(4-ethoxyphenyl)eten-1-il]-2,2- dimethylcyclopropane-1-carboxylate (1.14) were produced through the reaction of Wittig, starting from the aldehyde (1.7) with yielding of 46, 45, 64, 50 and 65%, respectively. The second chapter is about an alternative route for pyrethroids synthesis that has as intermediary stage a reaction photochemistry of photoadition of isopropylic alcohol. This route uses the phurphural (2.1) as first material that was initially submitted to an oxidation reaction to give the 5H-furan-2-one (2.2a) in 40% of yielding. This last one was irradiated being used low-pressure mercury lamp (= 254 nm) in the presence of isopropylic alcohol, resulting 4-(1'-hydroxy-1'-methylethyl)tetrahydrofuran-2-one (2.3) in 92% of yielding. This alcohol was dehydrated being used phosphorus pentachloride in DCM for formation of alkenes 4-isopropeniltetrahydrofuran-2-one (2.4a) and 4-(1- methylethylideno)tetrahydrofuran-2-one (2.4b) in 90% of yielding. These alkenes were submitted to the reaction with phosphorus tribromide in DCM in the presence of silicon oxide for formation of bromide 4-(1'-bromide-1'-methylethyl)tetrahydrofuran-2-one (2.5) in 39% of yielding. This bromide was treated with potassium tert-butoxide in THF dry, taking the formation of 6,6-dimethyl-3-oxabicyclo[3.1.0]hexan-2-one (2.6) in 40% of yielding. The lactone (2.6) is an important middleman for synthesis of acid trans- chrysanthemic and several pyrethroids. The esters (1.4) was treated with sulfuric acid in methanol for the formation of (S)-5-hydroxymethyl(5H)furan-2-one (2.7) in 73% of yielding. Later on, the group hydroxyl of lactone (2.7) was protected being used tert- butyldimethylsilyl chloride in DCM in the presence of the imidazole, resulting (S)-5-O- tert-butyldimethylsiloxymethyl(5H)furan-2-one (2.8) in 60% of yielding. The lactones (2.8) and (2.7) were irradiated in the presence of isopropylic alcohol taking the formation of alcohols (4S,5S)-5-O-tert-butyldimethylsiloxymethyl-4-(1'-hydroxy-1'- methylethyl)tetrahydrofuran-2-one (2.9) and (4S,5S)-5-hydroxymethyl-4-(1'-hydroxy-1'- methylethyl)tetrahydrofuran-2-one (2.10) in 66 and 90% of yielding, respectively. The alcohol (2.10) was transformed into the (4S,5S)-5-benzoiloxymethyl-4-(1'-hydroxy-1'- methylethyl)tetrahydrofuran-2-one (2.11) in 90% of yielding, being used benzoil chloride in pyridine dry. In the Chapter 3, the results of irradiation are shown (= 254 nm) of esters (1.4) and of (2E,4E)-hexa-2,4-dienoic acid (3.2) in the presence of isopropylic alcohol. In the beginning, the potassium sorbate (3.1) was treated with hydrochloric acid to form the (2E,4E)-hexa-2,4-dienoic acid (3.2) in 87% of yielding. This acid was dissolved in isopropylic alcohol and irradiated by 96h, taking the formation of 2-methyl-3-oxo-1-cyclobutanecarboxylic acid (3.3) in 10% of yielding. This last one was reduced with lithium aluminum hydride to form the 3-hydroxymethyl- 2-methylcyclobutan-1-one (3.4) in 74% of yielding. The irradiation of acid (3.2) being used acetonitrile took the formation of (2Z,4E)-hexa-2,4-dienoic acid (3.5). After irradiation of esters (1.4), during 1h, was observed the formation of methyl 5-hydroxy- 4-oxopentanoate (3.6) in 85% of yielding. Finally, were made biological tests with the objective of evaluating the insecticide action of compositions (1.7), (1.9) to (1.14) and (2.6). Adults of Acanthoscelides obtectus (Say) (Coleoptera: Bruchidae) and Sitophilus zeamais Mots. (Coleoptera: Curculionidae), larvas of Ascia monuste orseis (Godart) (Lepidoptera: Pieridae) and nymphs of Periplaneta americana (L.) (Blattaria: Blattidae) were used to carry out these tests. All pyrethroids, were tested, presented significant insecticide action for the four species, 48h after its application.