
TY  - JOUR
A1  - Brown, DJ 
A1  - Lynn, RK 
T1  - Aza analogues of pteridine. VII. 3-Alhoxypyrimido[5,4-<I>e</I>]-<I>as</I>-triazines and some derivatives
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1973
VL  - 26
IS  - 8
SP  - 1689
EP  - 1699
KW  - 
UR  - https://doi.org/10.1071/CH9731689 
N2  - Syntheses and some reactions of 3-ethoxypyrimido[5,4-e]-as-triazines are described. For example, 4-hydrazino-6-methoxy-5-nitropyrimidine (3a) and ethyl orthocarbonate give the 4-(diethoxymethylene)hydrazino derivative (4a) which may be reduced to its 5-amino analogue (4b) and thence cyclized to the 3-ethoxy-1,2-dihydro-5-methoxypyrimidotriazine. This undergoes dehydrogenation by mercuric oxide to the 3-ethoxy-5- methoxypyrimidotriazine (1a). Such dialkoxypyrimidotriazines are aminolysed to 5-mono- or 3,5-di-amines, e.g. (1g) or (1e), according to conditions; similarly trialkoxypyrimidotriazines, e.g. (1p), undergo successive aminolysis at the 5-, 3-, and 7-position. In contrast, the 3-group proves to be least reactive during progressive acidic hydrolysis of trialkoxypyrimidotriazines to the trione (8). The tabu- lated ultraviolet and p.m.r. spectra serve to prove or confirm many of the structures. 
ER  -

