Vitamin B₁及び諸関係化合物の研究 (第33報)

Vitamin B₁の分解因子について その4

抄録

An Attempt was made to utilize the decomposition of thiaminase by sulfurous acid for the synthesis of allied compounds but it could not be made successfully. For example, reaction of N-benzylpyridinium chloride and aniline, in the presence of sulfurous acid, failed to yield the desired N-benzylaniline. Reaction of N-[2′-amino-4′-hydroxypteridyl-(6′)]-methyl-4-methyl-5-β-hydroxyethylthiazolium iodide and N-(p-aminobenzoyl)-glutamic acid, in the presence of sulfurous acid, also failed to give any indication of the formation of folic acid. Therefore, the relationship between this decomposition reaction and chemical structure was examined, and as a result, it was found that compounds in which the 2-position of the pyrimidine nucleus is substituted with ethyl radical (III) or the 4-position with methylamino radical (II) are decomposed almost similar to the case of thiamine (I), but that hydroxythiamines are not decomposed at all. In this case, the amino radical at 4-position has an important significance. Compounds in which the thiazole nucleus is substituted with methyl (IX), ethyl (X) or carbethoxyl (XI) in the 5 position, are also decomposed, the decomposition being promoted by the addition of aniline. However, the compounds in which the pyrimidine nucleus has been substituted with nitrobenzyl (VI), (VII), (VIII), or in which the thiazole nucleus has been substituted with benzothiazole (XII) are entirely indifferent to the decomposition.
The effect of the addition of thiamine analogs during this reaction to the decomposition of thiamine was examined from which it was learned that nitrobenzyl homologs (VI), (VII), (XIV) and 2′-methyl-4′-aminopyrimidyl homologs (XI) and (XVI) tended to inhibit decomposition, while o-aminobenzyl homologs (XIII) and (XV), and benzothiazole homologs (XII) promoted decomposition. Hydroxythiamine (IV) seemed to give no effect.