Studies on Pyrimidine Derivatives and Their Related Compounds. LXXVIII. Unusual Reactions of Thiamine Free Base with Some Electrophilic Reagents

Abstract

Reaction of thiamine free base (I) with ethyl pyrocarbonate afforded the 1: 1 adduct (VIII) which was hydrolyzed to IX via N-C bond cleavage of pyrimidopyrimidine nucleus of I. The reaction of I with ethyl chloroformate also afforded VIII, together with IX. On the other hand, the reaction of I with benzoyl chloride yielded dibenzoate (IV) as the major product and monobenzoate (V) as the minor product, these compound being analogues of IX. The mechanisms of these reactions are discussed as shown in Chart 2.