Tetra-Substituted Ethylenes

Abstract

As part of our studies into certain aspects of organosulphur chemistry we published recently a short communication concerning a new synthesis of tetra-substituted ethylenes. We have extended the scope of this reaction and have more closely defined the optimum experimental conditions. It appears that substituted alkyl acetates, and probably other alkyl esters, containing a further electron-with-drawing group and with a low enol content (approx. < 1%) or similar compounds having a methylene group activated by two electron-with-drawing groups, e.g. malononitrile, will react with thionyl chloride generally under reflux conditions to give the corresponding alkene, eq. 1. We have also found that similar compounds with a rather higher enol content will generally react with thionyl chloride in the cold to give a sulphinyl chloride or a sulphide or polysulphide, eq. 2.