Adi??o de organomet?licos a orto e paranaftoquinonas

Autor: Silva, Andrea Rosane da
Přispěvatelé: Ferreira, Aur?lio Baird Buarque, Pinto, Antonio Ventura, Costa, Jo?o Batista Neves da, Santa?Anna, Carlos Maur?cio Rabello
Jazyk: portugalština
Rok vydání: 2004
Předmět:
Zdroj: Biblioteca Digital de Teses e Dissertações da UFRRJ
Universidade Federal Rural do Rio de Janeiro (UFRRJ)
instacron:UFRRJ
Popis: Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2020-11-30T13:28:31Z No. of bitstreams: 1 2004 - Andrea Rosane da Silva.pdf: 7033760 bytes, checksum: fb930f4c82c3092d38828b0a8b3a2911 (MD5) Made available in DSpace on 2020-11-30T13:28:31Z (GMT). No. of bitstreams: 1 2004 - Andrea Rosane da Silva.pdf: 7033760 bytes, checksum: fb930f4c82c3092d38828b0a8b3a2911 (MD5) Previous issue date: 2004-11-13 Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq The objective of this work is the study of methylation, benzylation, allylation and propargylation reactions of ortho and para-naphthoquinones, derived from lapachol (2-methoxylapachol (2), ?-lapachone (3), a-lapachone (4) and a-xyloidone (5)) using organometallic reagents of magnesium, indium and tin. The initial reactions, with Grignard reagents (methyl-magnesium iodide, benzyl-magnesium chloride and allylmagnesium bromide), indicate that there is regioselectivity in the process, since the addition occurs, in most cases, at only one of the carbonyls, even when there is unused reagent after the reaction time. It is possible that coordination of the Grignard reagent by the oxygen of the pyran ring has an influence in the formation of the products. The reactions were not very clean, and formation of many by-products always occurred, with exception of reactions with ?-lapachone (3). Allylation and propargylation reactions were carried in aqueous solvent (Barbier-type reactions), using indium and tin as metals. In the reactions with tin, it was necessary to use an ultrasonic bath to force dissolution of the metal and start to the reaction. The best results resulted from the use of allyl-indium, because, in some cases, use of allyl-tin led to the destruction of part of the naphthoquinone reagent. The same selectivity seen previously with the Grignard reagents, was also observed in these reactions, but the yields, in this in case, were always superior, since there were not so many by-products. A great advantage in the use of the metal indium, beside the good yields, comes from reaction rates, much faster than those for tin. The propargylation with tin was not successful with a-lapachone (4) and 2-methoxylapachol (2), (there was practically no product formation), and with ?- lapachone there was only had a modest yield. With propargyl-indium the results were more inspiring, leading in some cases to formation of both allene and acetylene products. Este trabalho teve como objetivo estudar as rea??es de metila??o, benzila??o, alila??o e propargila??o de orto e para-naftoquinonas, derivadas do lapachol (2-metoxi-lapachol (2), b-lapachona (3), a-lapachona (4) e a-xiloidona (5)) empregando reagentes organomet?licos de magn?sio, ?ndio e estanho. As rea??es iniciais, feitas com reagentes de Grignard (iodeto de metil-magn?sio, brometo de alil-magn?sio e cloreto de benzilmagn?sio) indicam que existe regiosseletividade no processo, visto que, a adi??o ocorre na maioria dos casos em apenas uma das carbonilas, mesmo quando sobra reagente de partida ap?s o tempo de rea??o. A possibilidade do reagente de Grignard estar coordenado com o oxig?nio do anel pir?nico, pode ter influenciado na forma??o dos produtos. Estas rea??es n?o foram muito limpas, pois ocorria sempre a forma??o de muitos sub-produtos, com exce??o das rea??es com b-lapachona (3). As rea??es de alila??o e propargila??o utilizando como metais ?ndio e estanho foram realizadas em meio aquoso (rea??es do tipo Barbier). Nas rea??es com estanho, foi preciso utilizar banho de ultra-som, para que o metal se dissolvesse dando in?cio ? rea??o. Os melhores resultados correspondem ? adi??o com alil-?ndio, pois em alguns casos com alilestanho, ocorre a destrui??o de parte do reagente (naftoquinona). A mesma seletividade vista anteriormente com os regentes de Grignard, foi observada tamb?m nestas rea??es, sendo que os rendimentos, neste caso foram sempre superiores, pois n?o ocorreu a forma??o tantos sub-produtos. Uma grande vantagem na utiliza??o do metal ?ndio, al?m dos bons rendimentos, ? a velocidade das rea??es, pois estas s?o mais r?pida do que com estanho. A propargila??o com estanho n?o foi bem sucedida com a a-lapachona (4) e o 2-metoxi-lapachol (2), (praticamente n?o houve forma??o de produto) e com a blapachona obteve-se somente um modesto rendimento. Com propargil-?ndio os resultados foram mais animadores, obtendo-se em alguns casos a forma??o de produtos al?nico e acetil?nico. Palavas chave: lapachol, lapachona
Databáze: OpenAIRE
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