Data Sheet 1_Stereochemistry of furofuran lignans from optical rotatory dispersion: potential and pitfalls.pdf

Recently, we have demonstrated the impact of solvents of different polarities and H-bond capabilities on the vibrational circular dichroism of furofuran lignans.</p>Methods<p>In order to further investigate the solvation effects on the chiroptical properties of this class of secondary metabolites, as well as to explore more reliable protocols to assign absolute configuration based on OR, herein, we present a systematic experimental and theoretical investigation of the optical rotatory dispersion (ORD) of a series of furofuran lignans in CH₃CN, CHCl₃, and CH₃OH.

Specific rotations were measured at 589, 578, 546, 436, 405, and 365 nm and compared to DFT simulations at the B3LYP/PCM/6–311G++(d,p) level.</p>Results<p>Comparisons between experimental and calculated data revealed that the absolute configurations of the target lignans could be unambiguously assigned in all cases, but that of sesamin (2) in CH₃OH solution. The latter case was then investigated using molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) calculations.</p>Conclusion<p>Our results indicate that CHCl₃ is the preferable solvent for ORD, while CH₃OH should be used with caution as it unpredictably affects the simulations of electronic properties of this class of natural products.</p>