Reduction of Aromatic Dimethyl Ene-Dicarboxylates to Dimethyl Succinates with Titanium Ylides

Generally, it was assumed that Tebbe- and Takai-reagents are useful for methenylation reactions. Applying these reagents to aromatic ene dicarboxylates, unexpectedly the reduction of double bonds was achieved. There is, however, a different behaviour in both reagents. Takai-reagent yields reduction while Tebbe- reagent prefers isomerisation. It shows a selective and unique method to reduce a double bond of ene-dicarboxylates while both carboxylic groups are not affected at all. In addition, this method is easy and very cheap using Takai-reagent. If interested in just isomerisation, without any reduction of double bond, Tebbe-reagent can be applied. Due to our knowledge, such reactions were not published yet. We have shown a selective methodology to reduce aromatic ene-dicarboxylates with titanium ylides.