The insolubility of complex magnsium chelates makes experimentation difficult, so smaller complexes are used as models for NMR and deuteriation studies. Treatment of methyl cyanoacetate with magnesium methoxide however does not give a simple chelate but a novel kinetic Claisen condensation product, methyl 2,4-dicyano-3-hydroxybut-2-enoate, sequestrated as its magnesium-derivative. Replacement of magnesium methoxide by the non-chelating base sodium methoxide gives the known thermodynamic 1,2-addition product, dimethyl 3-amino-2-cyanopent-2-enedioate. A crossed Claisen product, dimethyl 2-cyano-3-hydroxybut-2-enedioate, has been obtained from diethyl oxalate and methyl cyanoacetate in the presence of magnesium methoxide. However, replacement of the oxalate by phenyl cyanomethyl sulfoxide gives a crossed 1,2-addition product, methyl 3-amino-2-cyano-4-phenylsulfinylbut-2-enoate.

Reactions between phenyl cyanomethyl sulfoxide or phenylsulfinylacetone and methyl 2-methoxy-methyleneacetoacetate are carried out in the presence of varying amounts of sodium and magnesium methoxides. The products are pyrones, pyridones and aminobenzoates. When sodium methoxide is used in the phenylsulfinylacetone reaction the major product is a pyridine, but with magnesium methoxide it is a hydroxyaminobenzoate. This dichotomy may be explained as a consequence of magnesium complexation by the substrate.