83% |
With pyridine In dichloromethane at -50 - 20℃; for 2h; Inert atmosphere; |
General Procedure for the Synthesis of 2,4,6-Tribromophloroglucinol-1,3,5-triyl Tris(trifluoromethanesulfonate) 1 and 2,4,6-Triiodophloroglucinol-1,3,5-triyl Tris(trifluoromethanesulfonate) 2
General procedure: A three necked round bottomed flask connected to an inert gas source and equipped with a thermometer, a dropping funnel with a pressure compensator, and a bubble counter was charged with a solution of initial halophloroglucinol (0.008 mol) in methylenechloride (100 mL). In inert gas flow on stirring and cooling (-50°C), trifluoromethanesulfonic anhydride (0.032 mol, 9 g, 5.4 mL) was slowly added first, next pyridine (0.04 mol, 3.16 g, 3.2 mL) was added, preventing a large growth of temperature of the reaction mixture. After addition of the reagents, the mixture was allowed to warm to ambient temperature, and then the reaction was continued for another 2 h. The liquids were removed in a vacuum, avoiding strong heating. The products were extracted from the oily residue with hot hexane. The obtained triflates were recrystallized from hexane. Triflates 1 and 2 are white crystalline solids stable on storage under anhydrous conditions at reduced temperature and readily solublein organic solvents. 2,4,6-Tribromophloroglucinol-1,3,5-triyl tris(trifluoromethanesulfonate) 1 (83%),mp 117-118°C (hexane)For 9Br3F99S3 anal. calcd. (%): C, 14.24;H, 0.00; S, 12.67.Found (%): C, 14.58; H, 0.20; S, 12.67.13C NMR (CDCl3, δ, ppm, JF-F, Hz): 146.10;118.45 (q, J = 322); 115.54.MS (EI, m/z): 623 (1 - OTf), 625, 627, 629 (inintensity ratio 1.00 : 3.14 : 3.10 : 1.14); 133 (Tf);69 (CF3). |