Preparation of Some 1-Alkyl-4-[1-(ethoxyimino)butyl]-3-hydroxy-5-oxocyclohex-3-ene-1-carboxylic Acid Ester and Amide Herbicides by Reductive Alkylation of 3,5-Dimethoxybenzoic Acid

Abstract

Reductive alkylation of 3,5-dimethoxybenzoic acid with haloalkanes afforded the 1-alkyl- 3,5-dimethoxycyclohexa-2,5-diene-1-carboxylic acid derivatives (3a-e) which, upon esterification and hydrolysis, furnished methyl 1-alkyl-3-hydroxy-5-oxocyclohex-3-ene-l-carboxylate derivatives (4f-j). Reaction of (4f-j) with butyric anhydride gave methyl 1-alkyl-4-butyryl- 3-hydroxy-5-oxocyclohex-3-ene-1-carboxylate derivatives (6a-e) which were converted into methyl 1-alkyl-4-[1-( ethoxyimino )butyl]-3-hydroxy-5-oxocyclohex-3-ene-1-carbo xyate derivatives (2a-e). Similarly, the oxime O-ether derivative (2f) was prepared from the amide (41), obtained from reaction of (3b) with N,N′- carbonyldiimidazole and dimethylamine followed by hydrolysis.