Patent ID: 10087152

Abstract:
A process for preparing (E)-(5,6-dihydro-1,4,2-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-1,4,2-dioxazin-3-yl)(2-hydroxyphenyl)methanone (9-methyl oxime (4);