Circular Dichroism of Polyacetoxyalkylpyrazolo-(3,4-b) Quinoxalines

The circular dichroism spectra of a series of polyacetoxy-alkylpyrozolo(3,4-b) quinoxalines showed multiple Cotton effects with opposite sign to that of the corresponding polyhyroxylalkyl analogs having the same configuration of the side chain. Polyacetoxyalkyl analogs having the S chirality at the C-1′ in the Fischer projection formula showed a positive Cotton effect centered at the long-wavelength absorption and those possessing the R chirality showed a negative Cotton effect at the same region. The sign of the Cotton effect at the long-wavelength absorption is in accord with the rotation at the sodium D line.