Study On The Synthesis And Process Of Important Intermediates Of Topramezone

Topramezone was developed by BASF Aktiengesellschaft. It is an efficient and low toxicity of organic heterocyclic herbicide. In this paper, the synthesis process of Topramezone was studied on with 3-nitro-oxylene as starting materials to get the target product by multistep reaction.With 3-nitro-o-xylene as raw materials which is economic and available; oximation synthesis to give 2-methyl-6-nitrobenzaldoxime(Ⅰ), and the addition of ethylene to give 2-(4,5-dihydroisoxazol-3-yl)-3-methylnitrobenzene(Ⅱ), and the nitro group then replaced methylthio bromide to give 2-(4,5-dihydroisoxazol-3-yl)-3-methyl aniline(Ⅲ), then through diazotization Synthesis of 3-(2-methyl-6-methylthiophenyl)-4,5-dihydroisoxazole(Ⅳ), after bromide to give 3-(3-bromo-2-methyl-6-methylthiophenyl)-4,5-dihydroisoxazole(Ⅴ), Finally thiomethyl oxidized to give the object product 3-(3-bromo-2-methyl-6-methylsulfonylphenyl)-4,5-dihydro-isoxazole(Ⅵ), The Topramezone by the target product can be condensed with the other intermediate 1-methyl-5-hydroxypyrazole rearrangement. This structures of both intermediates and products were characterized by 1H-NMR and GC-MS. While the major factors were also discussed in this paper. The total yield was up to 31.1% with six steps(calculated with 3-nitro-o-xylene as the starting material) and the purity of the target was 96.7%(HPLC).