CH. 



CH. 



SYNTHESIS 



OH H H 



N— CH— C C C— CHoOH 



H OH OH 



H H 

 CH,v /^ /NH— CH,— CO— C C— CH2OH ^^ 



CH3/^V/ 

 CH 



CH 

 CH. 



I I 



CH, 



CH, 



CH, 



OH OH 



H H H 



.NH— CH2— C C C— CH.OH 



OH OH OH 



H H H 



.NH— CH2— C C C— CH^OH 



OH OH OH 



H H H 



NH— CH2— C C C— CH2OH 



OH OH OH 



NH, 



that brought about an Amadori rearrangement, with formation of 

 3 : 4-dimethylphenyl-D-isoarabinosamine. This was coupled in the 

 usual way with a diazonium salt, and the product was hydrogenated 

 to reduce the carbonyl to a carbinol group and the azo to an amino 

 group. The resulting compound was coupled with alloxan, dialuric 

 acid, isodialuric acid or alloxantin. 



Pfizer & Co.^^ used a different method for avoiding ribose, namely, 

 acetylation of D-ribonamide, conversion of the product into tetra- 

 acetyl-ribonic acid by treatment with nitrous acid, and then reaction 

 with phosphorus pentachloride to form the acid chloride. This was 

 reduced catalytically in presence of palladium supported on 

 barium sulphate, giving tetraacetyl-D-ribose. This compound, which 

 is claimed to exist in the aldehydo form, was hydrogenated in presence 

 of 0-4-xylidine, using Raney nickel or platinum as catalyst, giving 

 tetraacetyl-D-ribityl-o-4-xylidine. This was coupled with a phenyl 

 diazonium salt. In a similar method, due to Merck,^^ tetrabutyryl- 

 D-ribonamide was converted into tetrabutyrylribonic acid by the 

 10 145 



