Reaction Steps
To a suspension of Intermediate 22d (58 mg, 0.0917 mmol) and formaldehyde (37% wt in water, 0.074 mL, 0.917 mmol) in DCM-MeOH (4:1, 2.5 mL), were added AcOH (0.0105 mL, 0.183 mmol) and NaBH(OAc)3 (38.8 mg, 0.183 mmol) sequentially, then the solution stirred at RT for 2.5 h. The solution was concentrated in vacuo to ˜0.5 mL volume, diluted with MeOH (0.5 mL), then applied to an SCX-2 cartridge and washed with MeOH (15 mL). The product was eluted with 2M NH3 in MeOH (15 mL); concentration in vacuo left a pale brown solid. HPLC (XBridge C18, 40-98% MeCN in H2O, 0.1% NH4OH) gave the title compound as a white solid after freeze-drying (15.0 mg, 25%). LCMS (Method 5): Rt 3.66 min, m/z 647 [MH+]. 1H NMR (400 MHz, d6-DMSO): 1.22 (9H, s), 1.26 (2H, m), 1.58 (2H, d, J 12.6), 1.75 (2H, t, J 11.4), 1.78-1.92 (3H, m), 2.03 (2H, m), 2.07 (3H, s), 2.31 (3H, s), 2.68 (2H, d, J 10.7), 2.97 (2H, d, J 7.0), 4.78 (1H, m), 5.48 (1H, t, J 4.5), 6.27 (1H, s), 7.07 (1H, d, J 8.5), 7.11 (1H, dd, J 9.5, 2.0), 7.23-7.35 (8H, m), 7.63 (1H, d, J 9.8), 8.03 (1H, s), 8.17 (1H, s).
