Methyl 2-[2-(benzyloxycarbonylamino)propan-2-yl]-5-hydroxy-6-methoxypyrimidine-4-carboxylate

In the title compound, C18H21N3O6, a pyrimidine derivative, the dihedral angle between the benzene and pyrimidine rings is 52.26 (12)°. The carboxylate unit is twisted with respect to the pyrimidine ring, making a dihedral angle of 12.33 (7)°. In the crystal, molecules are linked by a pair of O—H⋯O hydrogen bonds, forming an inversion dimer. The dimers are stacked into columns along the b axis through weak C—H⋯O interactions.

2-Thiouracil and its alkyl analogue, thiobarbital, are effective drugs against hyperthyroidism. Propylthiouracil is used as a drug for hyperthyroidism with minimum side effects (Cheng & Roth, 1971). Afloqualone has been evaluated as a successful anti-inflammatory agent with lower-back-pain patients (Tani et al., 1979). In view of the importance of pyrimidine derivatives, the title compound (I) was synthesized and its crystal structure was reported.
The molecule of (I), (Fig. 1), is a V-shaped structure with the dihedral angle between the benzene and pyrimidine rings  (Bernstein et al., 1995). The bond distances are of normal values (Allen et al., 1987).
In the crystal packing ( Fig. 2), the molecules are linked bya pair of O-H···O hydrogen bonds (Table 1), forming an inversion dimer. These dimers are stacked into columns along the b axis through weak C-H···O interactions ( Table 1). The crystal is solidated and stabilized by O-H···O hydrogen bonds and C-H···O weak interactions (Table 1).

Experimental
The title compound was synthesized by taking benzyl (1-cyano-1-methylethyl) carbamate (0.10 mole) in xylene and dimethyl acetylene dicarboxylate (0.12 mole) was added. The reaction mixture is heated to 407 K and maintained at the temperature for 10 hrs until the reaction was completed. On cooling, the precipitated product, methyl 2-(1-{[(benzyloxy) carbonyl] amino}-1-methylethyl)-5,6-dihydroxypyrimidine-4-carboxylate, is filtered and washed with hexane. The sample is dried at 313 K for 4-5 hrs. The obtained material is taken in 5 volume of methanol and 0.22 mole of 5% sodium hydroxide in methanol. The mixture was cooled to 288 K and methyl iodide (0.20 mole) was then added and heated to 323 K. After the reaction was over, methanol was distilled off and the product was quenched in water and then filtered to get the title compound. Colorless block-shaped single crystals of the title compound suitable for x-ray structure determination were recrystalized from ethanol by the slow evaporation of the solvent at room temperature after several days, Mp. 391-393 K.
supplementary materials sup-2 Refinement Amide and hydroxy H atoms are located in a difference map and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for aromatic and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. Fig. 1. The molecular structure of the title compound, showing 40% probability displacement ellipsoids and the atom-numbering scheme. Hydrogen bond is shown as dashed line.   (7) −0.0084 (9) 0.0170 (9) C18 0.0458 (8) 0.0310 (7) 0.0596 (9) −0.0061 (6) 0.0016 (7) 0.0005 (6) Geometric parameters (Å, °)