MD‐based CD calculations for the assignment of the absolute axial configuration of the naphthylisoquinoline alkaloid dioncophylline A

The circular dichroism (CD) of the biaryl alkaloid dioncophylline A (2) was investigated by CD calculations; the structures were generated by molecular dynamics (MD) simulations using the force field CVFF. From these structures the CD spectra were calculated with the semiempirical method CNDO/2S. Summing up the single CD spectra yielded the final spectrum. In contrast to our earlier method based on the Boltzmann weighting, the MD‐assisted approach permitted to assign the flexible biaryl axis of dioncophylline A (2), which is found to be P.