Cyclopentanone → (+/-)-3-Benzyl-2-(1-cyclopentylamino-propyl)-3H-pyrrolo[2,1-f][1,2,4]triazin-4-one

Participants

Reaction Steps

A mixture of 2-(1-amino-propyl)-3-benzyl-3H-pyrrolo[2,1-f][1,2,4]triazin-4-one (Example 26, 50 mg, 0.16 mmol), cyclopentanone (13 mg, 0.16 mmol), anhydrous sodium acetate (26 mg, 0.32 mmol), 4 Å molecular sieves (50 mg) and 1,4-dioxane (10 mL) was stirred at room temperture for 40 min. The mixture was treated with sodium triacetoxyborohydride (51 mg, 0.24 mmol) in one portion and stirred at room temperature for 40 h. Additional portions of cyclopentanone (0.16 mmol) and sodium triacetoxyborohydride (0.16 mmol) were added to the mixture which was stirred for an additional 3.5 hours then filtered. The filtrate was partitioned between ethyl acetate and saturated sodium bicarbonate, the ethyl acetate phase washed with brine, dried (MgSO4) and concentrated. The residue was purified by flash column chromatography on silica gel eluting with ethyl acetate to give the title compound (40 mg, 71%): 1H NMR (DMSO-d6) δ 0.88 (t, 3H, J=7.15 Hz), 0.95 (m, 1H), 1.05 (m, 1H), 1.20 (m, 1H), 1.31 (m, 1H), 1.33 (m, 1H), 1.50–1.72 (m, 6H), 2.72 (m, 1H), 3.53 (m, 1H), 4.95 (m, 1H), 5.58 (m, 1H), 6.54 (s, 1H), 7.08 (s, 1H) 7.16 (s 2H), 7.24–7.35 (m, 3H), 7.35 (s, 1H).

Provenance & Evidence