Stereochemistry of furofuran lignans from optical rotatory dispersion: interplay between theory and experiment

• Grant number: 24/17686-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2025
• End date: December 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: João Marcos Batista Junior
• Grantee: Eric Yoshitaka Lee
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Federal de São Paulo (UNIFESP). Campus São José dos Campos. São José dos Campos , SP, Brazil
• Associated research grant: 23/12475-5 - Systematizing chiroptical properties of lignans: implications for correct absolute configuration assignments, AP.R

Abstract

Furofuran lignans are important bioactive secondary metabolites widely distributed in the plant kingdom. Even though their biosynthesis is described from the enantioselective dimerization of two phenylpropanoid units, varying enantiomeric compositions have been reported in different plant species. Additionally, their absolute configuration assignments are mostly based on empirical comparisons of optical rotation values and electronic circular dichroism spectra obtained for structurally related molecules. Since the main structural differences among furofuran lignans reside on the substitution patterns of the aromatic moieties, as well as their relative orientations, this approach is risky and prone to error propagation. Currently, the most reliable procedure to use chiroptical spectroscopy involves the comparison of experimental data with those obtained by quantum chemical calculations. Thus, in the present project, the use of optical rotatory dispersion (ORD) and density functional theory (DFT) calculations is proposed for the stereochemical analysis of the furofuran lignans sesamin, episesamin, eudesmin, epieudesmin, kobusin and phillygenin isolated from Aristolochiaceae species. The results to be obtained will allow for an independent verification of the absolute configurations reported in the literature, besides providing information about the influence of different structural features for the specific rotation of this class of secondary metabolites.