1,2-Dibromo-1,1,2,2-tetrafluoroethane → 2-Bromo-6-(3-methoxy-4-triisopropylsilanyloxy-phenyl)-5,6-dihydro-4H-thieno[2,3-c]pyridin-7-one

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Reaction Steps

Dissolve 6-(3-methoxy-4-triisopropylsilanyloxy-phenyl)-5,6-dihydro-4H-thieno[2,3-c]pyridin-7-one (5 g, 11.6 mmol) in THF (100 mL) in a three neck round bottom flask. Cool the solution in a dry ice/acetone bath. In one neck, set up a chilled (dry ice/acetone) addition funnel containing 1,2-dibromo-1,1,2,2-tetrafluoro-ethane (2.8 mL, 23.2 mmol) in 10 mL THF. Add t-BuLi (9.7 mL of 1.2 M solution in pentane, 11.6 mmol) quickly through one of the side necks allowing the solution to run down the inside of the flask. Within 30 sec of completion of the t-BuLi addition, open the addition funnel containing the electrophile. Stir 5-10 min, then pour into aqueous NaHCO3 (300 mL) and extract with EtOAc (2×300 mL). Wash the combined organic layers with brine (200 mL). Concentrate and purify via silica gel chromatography using a 0-25% gradient of EtOAc/hexanes to give 2.78 g (47%) of the desired product. MS/ES m/z (79Br) δ 10.0 [M+H]+; Rf=0.52 in 4:1 Hexanes:EtOAc.

Provenance & Evidence