Sporidesmins. XVIII. The Infrared Solution Spectra (4000-1600 cm^-1) of Sporidesmin, Sporidesmin-B, Sporidesmin-D and Sporidesmin-E

Abstract

The solution infrared spectra of sporidesmin, sporidesmin-B, sporidesmin-D and sporidesmin-E have been determined in carbon tetrachloride. Though these compounds differ only slightly in structure, their spectra show marked differences which indicate differences in the intramolecular hydrogen bonding. These differences have been related to the known structures by using molecular models.    

In the v(OH) region, the spectra for sporidesmin-B and sporidesmin-E are similar, though the former compound has only one hydroxy group and the latter an epitrithio group. The spectrum for sporidesmin-D reflects the relaxation of the strain arising from the disulfide bridge in sporidesmin.    

The non-bonded carbonyls absorb at 1685-1718 cm^-1 and the corresponding bonded carbonyls absorb at 1657-1680 cm^-1. The Δv(C0) was greatest in sporidesmin-E.    

In the C-H stretching region, the spectra are similar except for sporidesmin-D where there are the extra absorptions for the two S- methyls.    

The instability of sporidesmin-E is discussed.