Reaktionsgleichung
[CH2:1]([O:3][C:4](=O)[CH2:5][O:6][C:7]1[CH:16]=[CH:15][CH:14]=[CH:13][C:8]=1C(OC)=O)[CH3:2].C(COC1C=CC=CC=1C(O)=O)(O)=[O:19].C(OC(=O)C)(=O)C.C([O-])(=O)C.[Na+]>>[C:1]([O:3][C:4]1[C:8]2[CH:13]=[CH:14][CH:15]=[CH:16][C:7]=2[O:6][CH:5]=1)(=[O:19])[CH3:2]Komponenten
Versuchsvorschrift
Another synthesis of (E)-(5,6-dihydro-1,4,2-dioxazin-3-yl)(2-hydroxyphenyl)methanone O-methyl oxime (13) is illustrated in Scheme 2B. According to the synthesis, methyl salicylate reacts with ethyl chloroacetate in the presence of potassium carbonate to give methyl 2-(2-ethoxy-2-oxoethoxy)benzoate (6). Hydrolysis of methyl 2-(2-ethoxy-2-oxoethoxy)benzoate (6) followed by a consecutive cyclization of 2-(carboxymethoxy)benzoic acid (7) with acetic anhydride in the presence of sodium acetate gives benzofuran-3-yl acetate (8) which is converted to benzofuran-3(2H)-one (9) by methanolysis. Treatment of benzofuran-3(2H)-one (9) with O-methylhydroxylamine and sodium acetate affords benzofuran-3(2H)-one O-methyl oxime (10) which is oxidized with tert-butyl nitrate in hydrochloric acid to yield exclusively or predominantly (3E)-benzofuran-2,3-dione O3-methyl dioxime (11A). In the presence of potassium hydroxide and 2-haloethanol, the (3E)-benzofuran-2,3-dione O3-methyl dioxime (11A) may form (3E)-benzofuran-2,3-dione O2-(2-hydroxyethyl) O3-methyl dioxime (12A), which may undergo potassium hydroxide-catalyzed cyclization to provide (E)-(5,6-dihydro-1,4,2-dioxazin-3-yl)(2-hydroxyphenyl)methanone O-methyl oxime (13).
Quellen und Nachweise
- ORD-Eintrag
- ord-f94d476499a24d13a102eda09af680b7
- Quelldatensatz
- uspto-grants-2015_11
- Patentnummer
- US09193698B2
Verknüpfte Notizen
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