6-(3,5-Dimethylbenzyl)-5-ethyl-1-[(2-phenoxyethoxy)methyl]-1,2,3,4-tetrahydropyrimidine-2,4-dione

The six-membered ring of the uracil part of the title compound, C24H28N2O4, is nearly planar (r.m.s. deviation = 0.013 Å); the aromatic ring of the 3,5-dimethylbenzyl substitutent is aligned at 85.4 (1)° with respect to this mean plane. The phenyl ring of the substituent at the 1-position takes up two orientations in a 1:1 ratio. In the crystal, two molecules are liked by a pair of N—H⋯O hydrogen bonds, generating a centrosymmetric hydrogen-bonded dimer.

The six-membered ring of the uracil part of the title compound, C 24 H 28 N 2 O 4 , is nearly planar (r.m.s. deviation = 0.013 Å ); the aromatic ring of the 3,5-dimethylbenzyl substitutent is aligned at 85.4 (1) with respect to this mean plane. The phenyl ring of the substituent at the 1-position takes up two orientations in a 1:1 ratio. In the crystal, two molecules are liked by a pair of N-HÁ Á ÁO hydrogen bonds, generating a centrosymmetric hydrogen-bonded dimer.
The six-membered ring of the uracil part is planar. The aromatic ring of the 3,5-dimethylbenzyl substitutent is aligned at 85.4 (1)° with respect to this plane. The phenyl ring of the substituent at the 1-position is disordered over two orientations in a 1:1 ratio (Fig. 1). Two molecules are liked by an N-H···O hydrogen bond to generate a centrosymmetric hydrogen-bonded dimer (Table 1).
Experimental 5-Ethyl-6-(3,5-dimethylbenzyl)uracil (0.258 g,1 mmol) was stirred in anhydrous acetontrile (15 ml) under nitrogen and N,O-bis(trimethylsilyl)acetamide (0.87 ml, 3.5 mol) was added. The clear solution -50° C and trimethylsilyl trifluoromethanesulfonate (0.18 ml, 1 mmol) was added followed by the dropwise addition of bis-(phenoxyethyloxy)methane (0.576 mg, 2 mmol). The mixture was stirred at room temperature for 4 h. The reaction was quenched with saturate sodium bicarbonate soluiton (5 ml). The solvent was evaporated under reduced pressure. The residue was extracted with ether (3 x 50 ml); the combined organic fractions were dried over magnesium sulfate. The solvent was removed and the residue was chromatographed on silica gel column with chloroform to afford a white solid. This was recrystallized from ethanol to yield the title compound as colorless crystals.

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H 0.95 to 0.98 Å, U iso (H) 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation.
The amino H-atom was located in a difference Fourier map, and was freely refined.