RIBOFLAVINE 



action of oxides of nitrogen, and the acid was converted via the acid 

 halide into tetrabutyryl ribose, as in Pfizer's method. 



A somewhat different method of preparing N-(D-ribityl)-3 : 4- 

 dimethylaniline, again without the use of D-ribose, was described by 

 Tishler et al}"^ D-Arabonic acid was converted into D-ribonic acid, 

 from which D-ribonolactone was prepared. This was reacted with 

 3 : 4-dimethylaniline and the product acetylated to give 3 : 4-dimethyl 

 (tetraacetyl-D-ribonyl)-aniline. This with phosphorus pentachloride 

 gave the chloroimine, which was reduced catalytically to the amine 

 and then deacetylated : 



CH3. y. .NH . CO . (CHOAc), . CHaOAc 



I II ' 



Cl 



CH3S yv .N = C . (CHOAc), . CH2OAC 



CH. 



CH3. .. ^NH . CH2 . (CHOH)s . CH2OH 



Another method not involving ribose was described by M. Tishler 

 and J. W. Wellman.^® 3 : 4-Dimethylaniline was reductively con- 

 densed with tetraacetyl-D-ribononitrile, which was prepared from 

 ribonic acid via the amide. The resulting N-tetraacetyl-D-ribityl-3 : 4- 

 dimethylaniline was then coupled with ^-nitrophenyl diazonium 

 chloride and the product reduced to 5-tetraacetyl-ribitylamino-4- 

 amino-i : 2-dimethylbenzene. This was hydrolysed and the product 

 coupled, not with alloxan as in the methods previously described, but 

 with 5 : 5-dichlorobarbituric acid ; for, contrary to the report of R. 

 Kuhn and A. H. Cook ^® that alloxazines could not be prepared by the 

 interaction of o-phenylene diamine and 5-bromo-barbituric acid, Tishler 

 et al}^ found that under certain conditions 5-chloro- and 5 : 5-dichloro- 

 barbituric acids reacted with alkylated o-phenylene diamines to give 

 alloxazines, e.g. 4 : 5-dimethyl-o-phenylene diamine and 5 : 5-dichloro- 

 barbituric acid gave 6 : 7-dimethylalloxazine : 



CH, 



/ 



Y''"^co 



I 



^co/ 

 146 



n/'^co/ 



