It has been established that an addition of bromine to 2-methyl-1,2-epoxy-4-hexen-3-ones leads to the mixture of two diastereoisomers of dibromoepoxyketones. In influence on mixture of diastereoisomers of 4,5-dibrom-2-methyl-1,2-epoxy-3-hexanes of equimolar quantity of triethylamine in acetone it takes place their partial dehydrobromination with formation of Е- and Z-isomers of 4,5-4-brom-2-methyl-1,2-epoxy-4-hexen-3-on. In a case of increase of reaction time of dibromoepoxyketones with excess of triethylamine in acetone it takes place the dehydrobromination with formation of 2-methyl-1,2-epoxy-4-hexyn-3-one.