Pyridine → 5-Bromo-1-(tert-butyl-dimethyl-silanyl)-2,3-dihydro-1H-pyrrolo[2,3-b]pyridine

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Reaction Steps

To a stirred and cooled (0° C.) solution of the azaindoline 3 (1.1 g, 4.7 mmol) in CH2Cl2 (25 mL) and pyridine (0.46 mL, 5.6 mmol) was added dropwise a solution of bromine (0.24 mL, 4.7 mmol) in CH2Cl2 (15 mL) over a period of 13 min. After a further 20 min stirring the mixture was diluted with a NaHCO3—Na2S2O3 (1:1 v/v) solution and stirred vigorously for 50 min. The resulting mixture was partitioned and the aqueous layer extracted with CH2Cl2 (3×). The combined organic extracts were dried (MgSO4), filtered and concentrated. The residue was purified by SGC with hexane:AcOEt as eluent (in gradient up to 1.3% AcOEt) to afford the bromo derivative 4 (1.13 g, 77%) as a pale yellow oil. 1H NMR (400 MHz; CDCl3) δ 0.31 (s, 6H), 0.95 (s, 9H), 2.99 (t, J=9.1 Hz, 2H), 3.67 (t, J=9.1 Hz, 2H), 7.20 (m, 1H), 7.79 (m, 1H).

Provenance & Evidence