A PROCESS FOR THE STEREOSELECTIVE PREPARATION OF INSECTICIDE 6,7,8,9,10-10-HEXAHALO-1,5,5A,6,9,9A-HEXAHYDRO-6,9-METHANO-2,4,3-BENZODIOXATHIEPIN-3-OXIDE

摘要

A process for the stereoselective preparation of insecticide 6,7,8,9,10,10-hexahalo-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide of general formula (I), wherein X is a halogen such as fluorine, chlorine or bromine. The process comprises reacting 1,4,5,6,7,7-hexahalo-5-norbornene-2,3-dimethanol of the general formula IV: wherein X is as defined above, with a cyclic sulfite ring forming reagent optionally in an inert organic solvent at ambient to 139 °C, wherein the reaction is carried out in the presence of a stereo isomer directing agent comprising an isomer of the compound of the formula (I) different from the desired isomer. The molar ratio of the stereoisomer directing agent to the dimethanol compound of the formula (IV) is at least 0.07.