7-Benzyloxy-3,4-dihydroquinazolin-4-one (7.0 g, 27 mmol) was suspended in dry DMF (50 ml) and cooled to 5-10° C., then sodium hydride was added (1.22 g of a 60% suspension in mineral oil, 30 mmol). The reaction mixture was allowed to return to ambient temperature and chloromethyl pivalate (4.75 g, 31.5 mmol) was added over 10 minutes and the mixture stirred for 1 hour. The reaction mixture was quenched with water (250 ml), the aqueous phase adjusted to pH5 and extracted with ether (300 ml×3). The combined ether phases were washed with brine, dried (MgSO4) and the solvent removed by evaporation. The solid residue was triturated with isohexane, collected by filtration and dried under vacuum to give 7-benzyloxy-3-((pivaloyloxy)methyl)-3,4-dihydroquinazolin-4-one (9.1 g, 90%).
