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

Abstract

The title compound, C15H16N2O5, 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.