To a 10 mL vial was added 5-((6-bromopyridin-2-yl)methyl)-2-chloro-5,6,6a,7,9,10-hexahydro-[1,4]oxazino[3,4-h]pteridine (PREPARATION x27, 75 mg, 0.189 mmol), K2CO3 (52.3 mg, 0.378 mmol), PdCl2(dppf) (13.83 mg, 0.019 mmol) and 2,4,6-trimethyl-1,3,5,2,4,6-trioxatriborinane (0.053 mL, 0.378 mmol) in dioxane (2 mL) and H2O (0.4 mL) to give an orange suspension. The reaction vial was sealed, heated to 100° C., and stirred overnight. The reaction mixture was then diluted with ethyl acetate and washed with aqueous saturated NH4Cl (3×10 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo to give crude product, which was loaded onto an ISCO® silica gel cartridge (4 g) and eluted using an ethyl acetate/hexane gradient. The product was collected and concentrated in vacuo to afford the title compound as a yellow solid (36 mg, 57%). 1H NMR (400 MHz, DMSO-d6) δ 2.45 (s, 3H), 2.92-3.05 (m, 1H), 3.12-3.27 (m, 2H), 3.40-3.52 (m, 2H), 3.61-3.74 (m, 1H), 3.85-4.00 (m, 2H), 4.18-4.28 (m, 1H), 4.35-4.58 (m, 2H), 7.10-7.17 (m, 2H), 7.30 (s, 1H), 7.60-7.68 (m, 1H). ESI-MS m/z [M+H]+ calc'd for C16H18ClN5O, 331.12. found 331.2.
