ANALOGUES 



possessed vitamin Bj activity. Their constitution is represented by 

 the following formula : 



CH3 

 .C=C . R, 



Nr=C . Ri 



I I 



CH3.C C— CHa— N 



II II / 



N— CH CI 



in which R^, Rg and Rg were : 



/ 



— S 



HCl 



The first of these compounds differed from aneurine only in the 

 absence of the hydroxyethyl group, which is therefore essential for 

 biological activity, as might be expected, since the hydroxyl group is 

 the point of attachment of the pyrophosphate radicle in cocarboxylase. 

 Compound 3 differed from aneurine only in the replacement of the 

 cimino group by a hydroxyl group ; evidently the presence of the 

 amino group is also essential. The most surprising result of the 

 series is the inactivity of compound 4, which merely contains an 

 additional methyl group in the thiazole ring! The loss of activity 

 would be understsmdable if Williams and Zima's hypothesis (page 10 1) 

 were true and cleavage of the thiazole ring were essential for aneurine 

 to exercise its function, but this idea has not received support. 



H. Andersag and K. Westphal,^ in the course of their synthesis of 

 the vitamin, prepared an isomer of aneurine, 3-(4'-amino-6'-methyl- 

 pyrimidyl-5 '-methyl) -5-jS-hydroxyethyl-4-methyl-thiazolium chloride, 

 which they stated to be active, although they did not record its ac- 

 tivity relative to that of aneurine ;^ F. Schultz * found it to be only 

 slightly active, however. It gave a positive thiochrome reaction. 



B. C. J. G. Knight and H. Mcllwain ^ tested a number of aneurine 

 analogues and pyrimidine and thiazole derivatives by means of a 

 strain of Staphylococcus aureus that would not grow on a synthetic 

 medium unless either aneurine or both the pyrimidine and thiazole 

 moieties were present. They found that 3-(4'-amino-2'-methyl-5'- 

 pyrimidyl - methyl) - 5-a-hydroxyethyl - 4 - methyl - thiazolium chloride, 

 which differs from aneurine only in the position of the hydroxyl group 



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