Tributylborane → 4-[6-(4-Fluorophenyl)spiro[2.4]hept-5-en-5-yl]benzenesulfonamide

Participants

Reaction Steps

Under nitrogen, a solution of 90 mg (0.248 mmol) of 5-(4-fluoro phenyl)-6-[4-(methylsulfonyl)phenyl]spiro[2.4]hept-5-ene from step 11 in 1 mL of THF at -78° C. was treated with 0.21 mL (0.27 mmol) of methyllithium (1.3M in ether) over a period of 2 minutes. The reaction was stirred at ambient temperature for 25 minutes, cooled to -78° C., and treated with 0.3 mL (0.3 mmol) of tributylborane (1.0M in THF). The resulting dark brown solution was stirred at ambient temperature for 20 minutes and then at reflux for 16 hour prior to the addition of 350 mg (4.27 mmol) of sodium acetate, 2 mL of water, and 250 mg (2.21 mmol) of hydroxylamine-O-sulfonic acid. The resulting light orange mixture was stirred at ambient temperature for 3 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 24 mg (27%) of 4-[6-(4-fluorophenyl)spiro[2.4]hept-5-en-5-yl]benzenesulfonamide as a colorless solid: mp 131.0°-133.0° C.; NMR (CDCl3) δ 0.68 (s, 4H), 2.90 (s, 3H), 4.81 (s, 2H), 6.92 (t, J=9 Hz, 2H), 7.11 (dd, J=6 and 9 Hz, 2H), 7.27 (d, J=9 Hz, 2H), 7.74 (d, J=9 Hz, 2H). HRMS. Calc'd for C19H18FNO2S: 344.1121. Found: 344.1122. Anal. Calc'd for [C19H18FNO2S+0.1 CH3CO2 CH2CH3 ]: C, 66.16; H, 3.98; S, 9.11. Found: C, 65.86; H, 5.52; N, 3.92; S, 9.57.

Provenance & Evidence