Yao Shan
2011
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Journal
Modern Agrochemicals
Abstract
Ethyl 2-methyl-4-oxo-2-cyclohexen carboxylate was synthesized using ethyl acetoacetate and formaldehyde as the primary materials,and then ethyl 7,8-dihydro-5-methylchroman-6-carboxylate was prepared by the reaction of ethyl 2-methyl-4-oxo-2-cyclohexen carboxylate and 1-bromo-3-chloro-propane in the presence of Et4NBr as catalyst.Then,ethyl 7,8-dihydro-5-methylchroman-6-carboxylate was dehydrogenated with sulfur and hydrolyzed to give ethyl 5-methyl-chroman-6-carboxylic acid.Ethyl 5-methylchroman-6-carboxylic acid reacted with H2NNHBu-t to give N-5-methyl-1,4-benzodioxan-6-carbo-N'-tert-butylhydrazine which was the important intermediate of chromafenozide.Then chromafenozide was obtained by the reaction of the N-5-methyl-1,4-benzodioxan-6-carbo-N'-tert-butylhydrazine with 3,5-dimethlybenzolyl chloride.The total yield was 23.3%.