Chlorosulfonic acid → Ralfuranone A

Participants

Reaction Steps

To 20 mL of stirring chlorosulfonic acid cooled to −5° C. was added 3,4-diphenyl-2-(5H)-furanone (Step 1)(3.160 g, 13.4 mmol) portion-wise over 30 minutes. The solution was warmed to room temperature and maintained at that temperature for 16 hours. The reaction mixture was diluted with dichloromethane and quenched into ice water. The phases were separated and the aqueous phase extracted with dichloromethane, the combined dichloromethane extract was dried over anhydrous MgSO4, filtered and concentrated in vacuo. The residue was diluted with dichloromethane and added to excess concentrated NH4OH. The mixture was stirred for 1 hour. The phases were separated and the aqueous phase was extracted with dichloromethane. The organic extract was dried over anhydrous MgSO4, filtered and concentrated in vacuo to give a white solid that was crystallized from aqueous ethanol to afford pure 3-[(4-aminosulfonyl)phenyl)]-4-phenyl-2-(5H)-furanone (2.110 g, 50%): mp 225.5-226.5° C. 1H NMR (CDCl3/300 MHz) 7.79 (d, 2H, J=8.4 Hz), 7.41 (d, 2H, J=8.4 Hz), 6.38 (brs, 2H), 5.09 (s, 2H). FABLRMS m/z 316 (m+H). Anal. Calc'd for C16H13NO4S: C, 60.94; H, 4.16; N, 4.44. Found: C, 60.86; H, 4.18; N, 4.40.

Provenance & Evidence