5 1 y Pyrimidines 



1006 Uracil, C4H4O2N2, colorless needles, m.p. ^-'335° (dec.)- 



O 



II 



O H 



Agaricus nehularis, yeasts 



Nils Lofgren, Bjorn Liining and Harry Hedstrom, Acta 

 Chem. Scand. 8 670 (1954). 



1007 Cytosine, C4H5ON3, large colorless crystals, m.p. ^320° (dec). 



NH2 



N 



O H 



Agaricus nehularis 



Nils Lofgren, Bjorn Liining and Harry Hedstrom, Acta 

 Chem. Scand. 8 670 (1954). 



1008 4,5-Diaminouracil, C4H6O2N4, has been shown to be a metabolite 

 of Eremothecium ashbyii by trapping with diacetyl. 



HN 



O' 



O H 



NH, 



NH2 



T. W. Goodwin and D. H. Treble, Biochem. J. 67 lOp (1957). 



1009 Uridine, CgHjoOgNs, colorless crystals, m.p. 165°, [a]D^° +6.4° 

 (10°) (in water). 



HOCH2 



"O 



/^N-^ 



O 



OH OH 



