Ethyl 2-(2-amino-5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7-yl)acetate.

The nine-membered fused-ring of the title compound, C(10)H(13)N(5)O(2), is approximately planar [maximum deviation = 0.012 (1) Å]; the bond angle at the methylene C atom is 111.33 (10)°. In the crystal, the amino group forms hydrogen bonds to the N atoms of the triazole rings of adjacent mol-ecules, generating a ribbon running along the a axis.