Carbon Dioxide → 1-(tert-butyldimethylsilyl)-5-(3-fluorophenyl)-1H-pyrrolo[2,3-b]pyridine-3-carboxylic acid

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Reaction Steps

1.7 M solution of t-BuLi in pentane (24.8 mL, 42.2 mmol) was added dropwise over a period of 25 min to a stirred and cooled (−78° C.) solution of 9 (8.20 g, 20.3 mmol) in THF (93 in L) at such a rate that the temperature did not exceed −65° C. After the addition, the mixture was stirred for 1 h at −78° C. Dry gaseous CO2 was introduced to the flask over a period of 10 min (exothermic reaction, external dry ice bath). When the exothermic reaction subsided, cooling bath was removed, and the mixture was allowed to reach 0° C. The mixture was then separated between brine-AcOEt. The aqueous layer was extracted with AcOEt (2×). Combined organic solutions were dried dried (MgSO4), concentrated and purified by SGC with CH2Cl2:AcOEt as eluent in gradient (up to 12% AcOEt) to afford 10 (5.74 g, 76%) as tan solid. 1H NMR (400 MHz, CDCl3) δ 0.71 (s, 6H), 0.99 (s, 9H), 7.05-7.12 (m, 1H), 7.37-7.42 (m, 1H), 7.43-7.50 (m, 2H), 8.11 (s, 1H), 8.58 (d, J=2.3 Hz, 1H), 8.61 (d, J=2.3 Hz, 1H).

Provenance & Evidence