Step i: 6-Amino-5-(2,2-diethoxyethyl)-2-mercapto-4-hydroxypyrimidine (11.6 mmol) [for preparation, see Davoll, J., J. Chem. Soc., 1960, pp131-138] was dissolved in a solvent mixture of water (150 mL) and aqueous ammonia solution (9 mL) and heated to 90°C. Raney Nickel suspension was added to the reaction mixture in batches (2-3 mL at a time) until TLC and LC/MS analysis showed that the reaction was complete. The reaction mixture was cooled to room temperature, filtered through a diatomaceous earth pad and the filter cake was washed with water (2 x 25 mL). The combined aqueous filtrates were freeze-dried to afford 6-amino-5-(2,2-diethoxyethyl)-4-hydroxypyrimidine as an off-white powder in a yield of 2.23 g (85%).LC/MS: RT = 1.37 min; m/z = 182 [M-EtOH + H]+ . Total run time was 3.75 min.1H NMR (DMSO-d6): δ 1.07 (t, 6H); 3.40 (m, 2H); 3.59 (m, 2H); 4.56 (t, 1H); 6.07 (br s, 2H); 7.70 (s, 1H); 11.43 (br s, 1H).
