The optical rotatory behaviour of lycorine and related compounds

The optical rotatory dispersion and the circular dichroism curves of lycorine and related compounds have been measured. The considerations of C2v symmetry and transition of the aromatic chromophore in these compounds allow a general rule to be deduced, like the octant rule, which, for an aromatic α-band relates the sign and magnitude of the Cotton effect to the spatial orientation of atoms about the benzene chromophore. It is shown that the Cotton effects of a number of lycorine derivatives support the general rule.