A Facile Baker-Venkataraman Synthesis of Flavones using Phase Transfer Catalysis

Activity of Host-derived Attractants and Their Related Compounds toward the Zoospores of PhytopathogenicAphanomyces cochlioides

“…A comparison of the attracting actIvIty of 8 (5-0H, 7-0Me) with that of 7 (5,, and that of 11 (5-0H, 6,7-diOMe) with that of 10 (5,6,7-triOH) revealed the significant contribution of 7-0-methylation to the intensity of activity. However, the 7-0-ethyl derivative (9) was an inferior attractant to the 7-0-methyl derivative (8), probably due to its steric effect.…”

“…6,7-Methylenedioxyflavone (2), 7-hydroxyflavone (6), 5,7-dihydroxyflavone (7), 5, 6,7-trihydroxyflavone (10), and 5,7-dihydroxy-4'-methoxyflavone (16) were synthesized according to the method of Agasimundin and Siddapa. 7 ) Flavone (4) and 5-hydroxyflavone (5) were obtained by the method ofJain et al 8) Compounds 7,10 and 5,7,4'-trihydroxyisoflavone (genistein, 14) were methylated to 5-hydroxy-7-methoxyflavone (8), 5-hydroxy-6,7-dimethoxyflavone (11), and 5,4'-dihydroxy-7-methoxyisoflavone (prunetin, 15) with diazomethane, respectively. 9) 5-Methoxy-6,7-methylenedioxyflavone (3) and 5-hydroxy-7,4'-dimethoxyflavone (13) were converted from 1 and 16 by methylating with dimethyl sulfate in a mixture of K 1 C0 3 and acetone, respectively.…”

Flavona e análogos como radioligantes para imageamento cerebral. Síntese, marcação com radioiodo e estudos <i>in vivo</i> frente a sítios receptores benzodiazepínicos

“…Frente à nucleófilos, o sistema cromona comporta-se como aceptor de Michael. Normalmente, o ataque ocorre no C-2, e em menor proporção no C-4, sendo que após a adição ocorre a transformação no anel (Fernández et ai, 2005;Kahnberg et ai., 2002;Marder et ai, 2001;Huang et ai, 2001;Viola et ai, 2000;Paladini et ai, 1998;March,1992;Jain, Makrandi, Grover, 1982).…”

“…2, e a espécie formada é tratada com base, formando uma 1,3-dicetona (3). O tratamento desta dicetona com ácido origina a flavona desejada (4) (Ono et ai., 2005;Fernández et ai, 2005;Kahnberg et ai., 2002;Marder et ai, 2001;Huang et ai, 2001;Viola et ai, 2000;Paladini et ai, 1998;Jain, Makrandi, Grover, 1982).…”

“…Em 1958, a reação de Baker-Venkataran foi modificada por Seshadri e colaboradores (Jain, Makrandi, Grover, 1982), e a proposta destes autores consiste em manter sob refluxo o-hidroxiacetofenona e cloreto de arila em presença de acetona e carbonato de potássio anidro, os quais originam diretamente a espécie 0hidroxidibenzoilmetano necessária para ciclização à flavona. Este procedimento simplificado, no entanto, apresentou algumas limitações.…”