A process for preparing (E)-(5,6-dihydro-l,4,2-dioxazin-3-yl)(2- hydroxyphenyl)methanone O-methyl oxime is described which includes: (i) reacting benzofuran-3(2H)-one O-methyl oxime (1) with at least one nitrite selected from n-butyl nitrite and tert-butyl nitrite, in the presence of a metal alkoxide to form (2Z,32)-2,3-benzofuran-dione O3-methyl dioxime (2) as the predominant isomer; (ii) reacting the (2Z,3Z)-2,3-benzofuran-dione O -methyl dioxime (2) with 2- haloethanol to form (2Z,3Z)-benzofuran-2,3-dione 02-(2-hydroxyethyl) O3 -methyl dioxime (3); and (iii) reacting the (2Z,3Z)-benzofuran-2,3-dione 02-(2-hydroxyethyl) & -methyl dioxime (3) with an acid to form (E)-(5,6-dihydro-l,4,2-dioxazin-3-yl)(2- hydroxyphenyl)methanone (9-methyl oxime (4);
描述了一种制备(E)-(5,6-二氢-1,4,2-二噁嗪-3-基)(2-羟基苯基)甲酮O-甲基
肟的方法,包括:(i)将
苯并呋喃-3(2H)-酮O-甲基
肟(1)与n-丁基
亚硝酸酯和叔丁基
亚硝酸酯中至少一种进行反应,在
金属烷氧化物存在下形成(2Z,3Z)-
2,3-苯并呋喃二酮O-3-甲基二
肟(2)作为主要异构体;(ii)将(2Z,3Z)-
2,3-苯并呋喃二酮O-甲基二
肟(2)与2-卤
乙醇反应,形成(2Z,3Z)-
苯并呋喃-2,3-二酮O2-(2-羟乙基)O3-甲基二
肟(3);(iii)将(2Z,3Z)-
苯并呋喃-2,3-二酮O2-(2-羟乙基)O-甲基二
肟(3)与酸反应,形成(E)-(5,6-二氢-1,4,2-二噁嗪-3-基)(2-羟基苯基)甲酮O-甲基
肟(4)。