Ethyl 5-methyl-4-oxo-3-phenyl-2-propyl-amino-3,4-dihydro-thieno[2,3-d]pyrimidine-6-carboxyl-ate.

The title compound, C(19)H(21)N(3)O(3)S, was synthesized via the aza-Wittig reaction of functionalized imino-phospho-rane with phenyl isocyanate under mild conditions. In the mol-ecule, the fused thienopyrimidine ring system is essentially planar, with a maximum deviation of 0.072 (2) Å, and makes a dihedral angle of 60.11 (9)° with the phenyl ring. An intra-molecular C-H⋯O hydrogen bond is present. The crystal packing is stabilized by inter-molecular N-H⋯O and C-H⋯O hydrogen bonds.