反应详情

Compounds of formula IV (X is CH) are prepared in an analogous manner by alkylation with methyl E-α-(2-bromomethylphenyl)-β-methoxyacrylate in the presence of a base, preferably NaOH or KOH, in a solvent, preferably acetone or methyl ethyl ketone. Methyl E-α-(2-bromomethylphenyl)-β-methoxyacrylate, as a single E isomer, can be prepared in two steps from 2-methylphenylacetate as described previously in U.S. Pat. No. 4,914,128. Compounds of formula V (X═N) are prepared by the reaction with methyl E-2-(bromomethyl)-phenyl-glyoxylate O-methyloxime in the presence of a base, preferably NaOH or KOH, in a solvent, preferably acetone or methyl ethyl ketone. Methyl 2-(bromomethyl)-phenylglyoxylate O-methyloxime can be prepared as described in U.S. Pat. Nos. 4,999,042 and 5,157,144. Methyl 2-(bromomethyl)-phenylglyoxylate O-methyl-oxime is prepared from methyl 2-methylphenyl-acetate by treatment with an alkyl nitrite under basic conditions to provide after methylation, methyl 2-methyl-phenyl-glyoxalate O-methyl oxime which can also be prepared from methyl 2-methyl-phenylglyoxalate by treatment with 2-hydroxylamine hydrochloride and methylation or by treatment with methoxylamine hydrochloride.