Addition of Lithiated Acetonitrile to β-Substituted Methylenemalonates. Revision and Correction

In the context of an attempt to prepare the 2-cyanoethylenemalonates 1 and 3, the addition of lithiated acetonitrile to the β-substituted methylenemalonates 2, 4, 6, and 8 was performed. Starting with 2 and 4, the dimers 5 and 10 were obtained instead of the expected addition products 1 and 3. The dimer 5 was formed exclusively from the adducts 7 and 9, obtained by addition of lithioacetonitrile to 6 and 8, upon elimination.