Improved Synthesis Of Pesticides Clethodim

Clethodim, one of herbicidal cyclohexanedione derivatives, exhibits surprisingly superior herbicidal activity against both pre- and post-emergent gramineous grass andsafly with respect to broad-leaf crops.This research optimizes the synthetical process on the base of plenty documents. Firstly, 3-ethylthiobutanal was prepared from crotonaldehyde reacting with ethanehiol in triethylamine with high yield. Secondly, methyl acetoacetate was converted to 6-ethylthiohept-3-en-2-one by three steps via hydrolysis, condensation with 3-ethyltio-butanal and dehydration, then 6-ethylthiohept-3-en-2-one was cycloco ndensed with dimethyl malonate by Michael addition and Claisen condensation, followed by saponification and decarboxylation to give the intermediate of 5-(2-ethylthiopropyl)-cyclohexane-1,3-dione. Finally, the dione was propylacylated with propionic anhydride, followed by a conventional oxime forming condensation with O-(3-chloro-2-propenyl)-hydroxylamine to get the title compound. The main compounds were confirmed by LC/MS.