Tributylborane → 4-[2(4-Fluorophenyl)-4,4-dimethylcyclopenten-1-yl)benzenesulfonamide

Participants

Reaction Steps

Under nitrogen, a solution of 4.55 g (13.2 mmol) of 1-[2-(4-fluoro phenyl)-4,4-dimethylcyclopenten-1-yl]-4-(methylsulfonyl)benzene (from Step 10 of Example 1) in 50 mL of THF at -78° C. was treated with 6.3 mL (0.27 mmol) of n-butyllithium (2.5M in hexane) over a period of 5 minutes. The reaction was stirred at ambient temperature for 25 minutes, cooled to -78° C., and treated with 19.8 mL (19.8 mmol ) of tributylborane (1.0M in THF). The resulting dark brown solution was stirred at ambient temperature for 30 minutes and then at reflux for 14 hours prior to the addition of 8.7 g (106 mmol) of sodium acetate, 37 mL of water, and 5.2 g (46 mmol) of hydroxyamine-O-sulfonic acid. The resulting light orange mixture was stirred at ambient temperature for 6 hours and the aqueous phase extracted with ethyl acetate. The combined extracts were washed with water, brine, dried (MgSO4), and concentrated in vacuo. The residue was chromatographed on silica gel to give 2.0 g (40%) of 4-[2(4-fluorophenyl)-4,4-dimethylcyclopenten-1-yl)benzenesulfonamide as a colorless solid: mp 117°-118° C.; NMR (CDCl3) δ1.24 (s, 6H), 2.70 (s, 4H), 4.72 (s, 2H), 6.92 (t, J=9 Hz, 2H), 7.09 (dd, J=9 and 7 Hz, 2H), 7.26 (d, J=8 Hz, 2H), 7.74 (d, J=9 Hz, 2H). HRMS. Calc'd for C19H20FNO2S: 345.1199. Found: 345.1194. Anal. Calc'd for [C19H20FNO2S+0.27 H2O]: C, 65.14; H, 5.91; N, 4.00; S, 9.11. Found: C, 65.07; H, 5.94; N, 3.86; S, 9.29.

Provenance & Evidence