抄録
Oxidation of O-benzoylthiamine disufide (I) with hydrogen peroxide in acetic acid yielded O-benzoylthiaminic acid (IIa) and its stereoisomerical compound (IIIa). It was confirmed that these two compounds were in the relation of geometrical isomers which have not yet been found in thiol-type thiamine derivatives : the compound obtained in this experiment was cis-2-(2-methy1-4-amino-5-pyrimidy) methylformamido-5-ben-zoyloxy-2-pentene-3-sulfonic acid (IIIa) of which olefin-CH3 and SO3- groups were in cis-configuration . Alkali decomposition of IIIa afforded cis-thiaminic acid (IIIb) corresponding to geometrical isomer of IIb. The configuration of these compounds was confirmed by elemental analyses, ultraviolet, infrared, nuclear magnetic resonance spectra and dissociation constants.
