| abstract |
A process for preparing alpha-keto carboxylic esters of the formula XmOCH2 YnC=O CH3O-CO where X and Y are each halogen, C1-C4-alkyl, C1-C4-alkoxy or trifluoromethyl; m is an integer from 0 to 4; n is an integer from 0 to 3, which comprises (a) reacting an o-phenoxymethylbenzoyl cyanide of the formula XmO-CH2 YnC=O CH(VI) where X, Y, m and n have the meanings specified above, with methanol or tert-butyl methyl ether in the presence of hydrogen chloride, (b) if required cleaving the keto carboxylic ester dimethyl acetal byprodunct of the formula XmOCH2 YnCOCH3 OCH3CH3OCO where X, Y, m and n have the meanings specified above, under acidic conditions, and, if required, subjecting the alpha-keto carboxamide byproducts of the formula XmOCH2Yn C=O NHRCO where X, Y, m and n have the meanings specified above and R is hydrogen or acyl, to step (a) again. Claimed as novel are the o-phenoxymethylbenzoyl cyanides of the formula VI. |