| 摘要 |
This invention relates to an improved process for the preparation of 5-methylchroman-6-carboxylic acid, a useful intermediate in the preparation of chroman-containing diacylhydrazines which are useful as insecticides, by reacting a Hagemann's ester with a propargyl derivative in the presence of a base and a solvent to produce a propargyl ether, and either (i) rearranging the propargyl ether by application of heat, optionally with a suitable catalyst and a solvent being present, to produce a cyclic ether type compound and isomerizing the cyclic ether type compound with a catalyst in a suitable solvent to produce a chroman ester, or (ii) rearranging the propargyl ether by application of heat, with a suitable catalyst and a solvent being present, to produce a chroman ester. The propargyl ethers and the cyclic ether type compounds produced by the process of the present invention are new. |
