Uracil-5-ylacetic acid (34, 1.0 g, 5.9 mmol) was transferred to a round bottomed flask equipped with a septum through which a flow of nitrogen was applied. Dry DMF (10 ml) and N-methylmorpholine (1.9 ml, 17.6 mmol) were transferred to the flask and the mixture was cooled to 0° C. Ethyl N-(2-BOC-aminoethyl)glycinate (1.6 g, 6.5 mmol) and O-(3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl)-N,N,N′,N′-tetramethyl uronium tetrafluoroborate (TDBTU, 2.5 g, 7.0 mmol) were added to the mixture. The reaction mixture was stirred for 3 hours at 0° C. and was then poured into ethyl acetate (300 ml). The resultant suspension was washed with saturated aqueous potassium hydrogen sulfate (2×50 ml), saturated aqueous sodium bicarbonate (2×50 ml) and with brine (1×50 ml). The organic phase was dried over magnesium sulfate, filtered and evaporated under reduced pressure. The residue was stirred overnight in dichloromethane (10 ml) and diethyl ether (40 ml). The resultant precipitate was isolated by filtration, washed once with diethyl ether and dried to give 1.13 g (48%) of the title compound as white crystals.
