Peracetic Acid → 1,4-Dimethyl-6-pentyl-2,3-dihydro-1H-pyrrolo[2,3-b]pyridin-5-yl acetate

Participants

Reaction Conditions

Reaction Steps

To a solution of 33.0 mg (0.11 mmol) of 5-bromo-1,4-dimethyl-6-pentyl-2,3-dihydro-1H-pyrrolo[2,3-b]pyridine in 1 mL of THF was added 16.5 μL (0.11 mmol) of tetramethylethylenediamine (TMEDA) at −78° C. followed by 139 μL (0.22 mmol, 1.6 M in hexanes) of n-BuLi. After 30 min, 27.2 μL (0.24 mmol) of trimethoxy boron was added and the resulting mixture was stirred for another 1 h. To the reaction mixture was added slowly 51.4 μL (0.24 mmol, 32 wt %) of peracetic acid and the solution was then warmed to 0° C. over a period of 30 min. The mixture was diluted by 5 mL of H2O and extracted with three 5-mL portions of EtOAc. The combined organic layer was washed with brine, dried (MgSO4) and the solvent was concentrated under diminished pressure. The resulting oil was dissolved in 2 mL of CH2Cl2 at 0° C., followed by the addition of 92.8 μL (0.66 mmol) of triethylamine, 1.40 mg (0.01 mmol) of DMAP and 31.4 μL (0.33 mmol) of acetic anhydride. The reaction mixture was stirred at room temperature for 1 h and quenched by the addition of 2 mL of sat aq NH4Cl. The solution was then extracted with three 5-mL portions of EtOAc. The combined organic layer was washed with brine, dried (MgSO4) and the solvent was concentrated under diminished pressure. The residue was purified by flash chromatography on a silica gel column (20 1.7 cm). Elution with 100:1 hexanes/ethyl acetate gave 2a as a yellow oil: yield 26.7 mg (88%); silica gel TLC Rf 0.1 (3:7 EtOAt/hexanes); 1H NMR (CDCl3) δ 0.90 (t, 3H, J=7.0 Hz), 1.32-1.37 (m, 4H), 1.64 (quint, 2H, J=7.5 Hz), 1.95 (s, 3H), 2.31 (s, 3H), 2.47 (t, 2H, J=8.0 Hz), 2.85 (t, 2H, J=8.0 Hz), 2.89 (s, 3H) and 3.44 (t, 2H, J=8.0 Hz); 13C NMR (CDCl3) δ 14.0, 20.6, 22.5, 24.7, 28.4, 29.6, 31.8, 32.5, 33.3, 52.4, 120.1, 134.7, 136.5, 149.7, 161.2 and 169.9; mass spectrum, m/z 276.2 (M)+ (theoretical 276.2); mass spectrum (APCI), m/z 277.1910 (M+H)+ (C16H25N2O2 requires 277.1916).

Provenance & Evidence