A convenient one-pot synthesis, theoretical studies, and NMR-based conformational analysis of nitroarylidene dimalonates

Tandem Knoevenagel-Michael addition of diethyl malonate to nitro-substituted benzaldehydes was found to proceed in a mild and convenient process. The H-1 NMR spectra of the products showed significant changes according to the position of the nitro group. Conformational analysis calculations confirmed that in all cases, a structure containing a mirror plane occurred at energies near the ground state. However, for the meta and ortho substituted products, increased steric crowding resulted in decreased rotational freedom of the ethyl substituents. Consistent with the observation of increased steric stress, molecular orbital calculations predicted a higher electrophilic reactivity of the ortho nitro substituted product. (C) 2022 Elsevier B.V. All rights reserved.