Methyl 6-methoxy­carbonyl­methyl-2-oxo-4-phenyl-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

The title compound, C(15)H(16)N(2)O(5), belongs to the class of monastrol-type anti-­cancer agents and was selected for crystal structure determination in order to determine the conformational details needed for subsequent structure–activity relationship studies. The central tetra­hydro­pyrimidine ring has a flat-envelope conformation. The 4-phenyl group occupies a pseudo-axial position and is inclined at an angle of ca 90° to the mean plane of the heterocyclic ring. Of the two methyl ester groups, one (in the 5-position) is in a coplanar and the other (in the 6-position) in a perpendicular orientation with respect to the heterocyclic plane. The coplanar 5-ester group has its carbonyl bond oriented cis with respect to the pyrimidine C=C double bond. By comparison of the structural results for the present compound with those determined previously for its diethyl analogue, we have identified the mol­ecular factors which control the dual course of the Biginelli reaction with salicylaldehyde. The crystal structure is dominated by two hydrogen bonds which link the mol­ecules into chains of dimers.