在氮气保护下,将温度降至-78℃,向1,3-二氟苯(10.00 g,87 mmol)的无水四氢呋喃(50 mL)溶液中缓慢滴加2.5 M 正丁基锂(42 mL,105 mmol)。滴毕后,在-78℃下保持反应10分钟,随后升至室温并维持5分钟。接着,将碘(26.7 g,105 mmol)的四氢呋喃(200 mL)溶液缓慢滴入上述反应液中,并在室温下搅拌4小时。反应完成后,逐渐加入水以淬灭反应,随后用二氯甲烷萃取产物。有机相经饱和食盐水洗涤后,用无水硫酸钠干燥并真空浓缩得到目标化合物2,6-二氟碘苯。
中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
2,3,4,5,6-五氟碘苯 | 1,2,3,4,5-pentafluoro-6-iodobenzene | 827-15-6 | C6F5I | 293.963 |
中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
2,4-二氟碘苯 | 2,4-difluoro-1-iodobenzene | 2265-93-2 | C6H3F2I | 239.991 |
—— | 2,4-difluoro-3-iodoaniline | 1437316-91-0 | C6H4F2IN | 255.006 |
Halodimethylsulfonium halide 1, which is readily formed in situ from hydrohaloic acid and DMSO, is a good nucleophilic halide. This activated nucleophilic halide rapidly converts aryldiazonium salt prepared in situ by the same hydrohaloic acid and nitrite ion to aryl chlorides, bromides, or iodides in good yield. The combined action of nitrite ion and hydrohaloic acid in DMSO is required for the direct transformation of aromatic amines, which results in the production of aryl halides within 1 h. Substituted compounds with electron-donating or -withdrawing groups or sterically hindered aromatic amines are also smoothly transformed to the corresponding aromatic halides. The only observed by-product is the deaminated arene (usually <7%). The isolated aryldiazonium salts can also be converted to the corresponding aryl halides using 1. The present method offers a facile, one-step procedure for transforming aminoarenes to haloarenes and lacks the environmental pollutants that usually accompany the Sandmeyer reaction using copper halides. Key words: aminoarenes, haloarenes, halodimethylsulfonium halide, halogenation, amination.