Abstract
The studies on the reactivity of thiazolium ylide of thiamine were carried out and the following new informations were obtained. 1. The nucleophilic reaction of thiazolium ylide of thiamine with aldehydes afforded not only the known HET type products but also the unknown new keto type products under the hydrophobic conditions. It was also investigated that the reactions of thiazolium ylide of thiamine with α-ketoaldehydes, dialkylacylphosphonates, dialkylhydrogenphosphonates, isocyanates and isothiocyanates produced the various type of adducts most of which provided the interesting reaction behaviours respectively. 2. The electrophilic reaction of thiazole-C_2-carbon of thiamine with cyclic secondary amines afforded 1 : 1 adduct. 3. Reaction of thiamine sodium salt with carbondioxide or the treatment of thiamine chloride salt with organic bases afforded thiamine free base as stable crystals which reacted with some electrophiles and ethyl chloroformate to give interesting unusual products respectively. 4. It became evident that there were marked differences of pyrimidine-C_4-substituted thiamine analogues, in the reaction with diethylbenzoylphosphonate, but we could not obtain the definite conclusion about the role of pyrimidine-C_4-NH_2 group of thiamine on the coenzymatic activity of thiamine from our experimental data mentioned above.
