Structural investigations of substituted methylenemalonaldehydes by X-ray crystallography and NMR spectroscopy

Abstract

Crystal and molecular structure of three substituted methylenemalonaldehydes I-III was studied. The spatial arrangement of the monosubstituted derivative I differs significantly from that of the disubstituted methylenemalonaldehydes II and III, not only in the solid state conformation of the malonaldehyde fragment but also in the length of the ethylenic C=C double bond and in its distorsion. The structures found in crystal are compared with conformations in solutions determined by NMR spectroscopy.