Abstract Reaction of the lithium thioenolate of methyl 2-methyldithiopropanoate with enones gives kinetic sulphur 1, 4-addition or thermodynamic carbon 1, 4-addition, with the exception of cyclopent-2-enone which gives kinetic carbon 1, 4-addition. In all caess 5-oxodithioesters can be prepared in good yields. No 1, 2-addition is observed, confirming the soft nucleophilic character of dithioester thioenolates.
