Abstract
Addition of primary amines to the aqueous solution of thiamine, in the presence of sulfurous acid, results in almost quantitative substitution of its thiazole portion with primary amines. Use of aniline and p-aminobenzoic acid as the primary amine, respectively yields N-[2-methyl-4-aminopyrimidyl-(5)]-methylaniline (I) and -methyl-p-aminobenzoic acid (IV), which are respectively identical with the substances obtained by the condensation of aniline or p-aminobenzoic acid with 2-methyl-4-amino-5-bromo-methylpyrimidine hydrobromide (III). This reaction also occurs with the use of indole, forming N-[2-methyl-4-aminopyrimidyl-(5)]-methylindole (V) from thiamine. (V) is identical with the substance obtained by the condensation of (III) and indole. The thiamine derivative substituted with pyridine or quinoline in its thiazole portion, i.e. N-[2-methyl-4-aminopyrimidyl-(5)]-methyl-pyridinium or -quinolinium compounds also form (I) in good yields in the presence of sulfurous acid and aniline. These results are quite similar to the state of decomposition of thiamine by the thiamine destructive enzyme and are of interest as a model experiment for enzymatic activity.
