First synthesis of furostans bearing a 1, 3-dioxane ring at C-26. XRD, Hirshfeld surfaces analysis, DFT studies

Abstract

The regioselective opening of ring F in diosgenin derivatives, in the presence of 2-substituted 1,3-propanediol, yielded new furostans bearing a 1,3-dioxane ring at C-26. The structures of these synthesized compounds 1e, 2a, 2b, 2c, 2d and 2e were established on the basis of spectroscopic data, including 1D and 2D NMR and ESI-HRMS. Single crystal X-ray diffraction analysis of 2e(22R,25R)-26-(5‑bromo-5-nitro-1,3-dioxanyl)furost-5-en-3-yl acetate not only helped in structural identification but also helped in ascertaining its stereochemistry. The molecular geometry of these compounds was calculated in ground state by density functional theory (DFT/B3LYP) using 6–31 G (d, p) basis set. The electronic properties such as HOMO and LUMO energy were calculated by using time dependent density functional theory (TD-DFT). The topological parameters-electron density (ρBCP), Laplacian of electron density (∇2ρ(rBCP)), energy parameters-kinetic electron energy density (GBCP), potential electron density (VBCP) and the total electron energy density (HBCP) at the bond critical points (BCP) were analyzed by ‘Atoms in molecules’ AIM theory. The Hirshfeld surface analysis helped in identifying important intermolecular interactions in 2e. Global reactivity descriptors and molecular electrostatic potential for compounds have also been determined. First hyperpolarizability (β0) of compounds has been computed to evaluate non-linear optical (NLO) response.