1-Bromoheptane → 1,4-dimethyl-6-octyl-2,3-dihydro-1H-pyrrolo[2,3-b]pyridine
Reaction equation
[CH3:1][N:2]1[C:6]2=[N:7][C:8]([CH3:12])=[CH:9][C:10]([CH3:11])=[C:5]2[CH2:4][CH2:3]1.[Li]CCCC.Br[CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH3:25]>C1COCC1>[CH3:1][N:2]1[C:6]2=[N:7][C:8]([CH2:12][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH3:25])=[CH:9][C:10]([CH3:11])=[C:5]2[CH2:4][CH2:3]1Participants
5
Procedure
To a solution containing −490 mg (2.71 mmol) of 1,4,6-Trimethyl-2,3-dihydro-1H-pyrrolo[2,3-b]pyridine in 7.2 mL of THF was added 2.70 mL (4.34 mmol) of n-BuLi (1.6 M in hexanes) followed by 4504 (509 mg, 2.85 mmol) of 1-bromoheptane at −78° C. The reaction mixture was slowly warmed to room temperature and stirred for 16 h. The reaction mixture was quenched by the addition of 25 mL of sat aq. NH4Cl at 0° C. The mixture was extracted with three 40-mL portions, of EtOAc. The combined organic layer was washed with brine, dried over anhydrous MgSO4, filtered, and concentrated under diminished pressure. The residue was purified via flash chromatography on a silica gel column (42×2.5 cm). Step gradient elution with 1:10→1:4 ethyl acetate-hexanes as eluent gave 1,4-dimethyl-6-octyl-2,3-dihydro-1H-pyrrolo[2,3-b]pyridine as a yellow oil: yield 402 mg (57%); silica gel TLC Rf 0.36 (8:1:1 hexanes-ethyl acetate-methanol); 1H NMR (CDCl3) δ 0.79 (t, 2H, J=7.2 Hz), 1.16-1.30 (m, 10H), 1.58 (quint, 2H, J=8.0 Hz), 2.00 (s, 3H), 2.48 (t, 2H, J=8.0 Hz), 2.72 (t, 2H, J=8.4 Hz), 2.82 (s, 3H), 3.38 (t, 2H, J=8.4 Hz), 6.14 (s, 1H).