
TY  - JOUR
A1  - Brown, DJ 
A1  - Lynn, RK 
T1  - Aza analogues of pteridine. VIII. 3-Amino- from 3-Alkoxy-pyrimido[5,4-<I>e</I>]-<I>as</I>-triazin- 5-ones prepared by cyclization of 3-Ethoxy-1,2,4-triazines or other means
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1974
VL  - 27
IS  - 8
SP  - 1781
EP  - 1790
KW  - 
UR  - https://doi.org/10.1071/CH9741781 
N2  - Syntheses of hitherto unknown 3-aminopyrimido[5,4-e]-as-triazin-5-ones are described. One route involves selective hydrolysis of 3,5-di- or 3,5,7-tri-alkoxypyrimidotriazines at the 5-position followed by aminolysis. Another is exemplified thus: 3-ethoxy-5-methoxypyrimidotriazine (2a) is converted by methanolic hydrochloric acid into methyl 6-amino-3-ethoxy-1,2,4-triazine-5-carboxylate (3a) which then undergoes successive ammonolysis to the corresponding amide (3b), cyclization by triethyl orthoformate-acetic anhydride to 3-ethoxypyrimidotriazin-5-one (1d) and final ammonolysis to the corresponding amine (1a). The second route may be modified to furnish 3-aminopyrimidotriazine- 5,7-dione (5c) and its 6-methyl derivative (5d). Dehydration of the above amide (3b) with phosphoryl chloride gives both the corresponding nitrile (3h) and an unusual hydrolytic product, 6-amino-3- ethoxytriazin-5-one (6). The ionization constants and the u.v., N.M.R. and mass spectra are discussed. 
ER  -

