Regiochemistry in 1,3-dipolar cycloadditions of the azomethine ylide formed from diethyl aminomalonate and paraformaldehyde.

The azomethine ylide derived from the condensation of diethyl aminomalonate with paraformaldehyde undergoes 1,3-dipolar cycloadditions with acrylate and propiolate derivatives. Contrary to a previous report, these reactions yield mixtures of regioisomers generally favoring the 2,2,3-trisubstituted product. However, the relative quantity of the 2,2,4-trisubstituted product formed increases with an increase in the size of the activating group on the dipolaroplile.