Fluorinated tertiary alcohols and alkoxides from nucleophilic trifluoromethylation of carbonyl compounds
作者:Stefan P. Kotun、John D. O. Anderson、Darryl D. Des Marteau
DOI:10.1021/jo00030a018
日期:1992.2
(CH3)3SiCF3 reacts with fluoro ketones in the presence of excess KF in CH3CN to produce alkoxides derived from formal addition of CF3- to the carbonyl carbon. These alkoxides may be isolated as such or acidified to the corresponding alcohols. Ketones to which this technique was applied include (CF3)2C = O, CF3C(O)CF2Cl, CF3C(O)CF2H, and [(CF3)2CF]2C = O. The last compound reacts with replacement of one of its perfluoroisopropyl groups by CF3. With 2 equiv of TMS-CF3, the acid fluorides RC(O)F (R = CF3CF2, n-C3F7, n-C7F15) yield products of the form RC(CF3)2OX (X = K, H) due to both substitution and addition of CF3 at the carbonyl. Similarly, F2C = O with 3 equiv of TMS-CF3 provides a novel and high-yield synthesis of the perfluoro-tert-butoxide group. Phosgene does not appear to react directly with the TMS-CF3/KF system, but is converted first to F2C = O. The intermediate ketone CF3CF2C(O)CF3 is observed in reactions of equimolar amounts of CF3CF2C(O)F and TMS-CF3.
在CH3CN中加入过量的KF,(CH3)3SiCF3与氟酮反应,生成羰基碳上形式上加成CF3-的烷氧基。这些烷氧基可以以游离酸的形式分离出来,也可以被酸化为相应的醇类。此方法应用于多种酮类,包括(CF3)2C=O、CF3C(O)CF2Cl、CF3C(O)CF2H和[(CF3)2CF]2C=O。其中,最后一个化合物反应时会将一个全氟异丙基群被CF3取代。
使用2当量的TMS-CF3,酸氟化物RC(O)F(R=CF3CF2、n-C3F7、n-C7F15)生成形式为RC(CF3)2OX(X=K、H)的产物,这是由于CF3在羰基上的取代以及加成所致。类似地,F2C=O与3当量的TMS-CF3反应,可以得到一种新型且高产率的全氟叔丁基醚的生成方法。
光气似乎不会直接与TMS-CF3/KF系统反应,而会首先转化为F2C=O。在研究等当量的CF3CF2C(O)F与TMS-CF3的反应时,观察到了中间体酮CF3CF2C(O)CF3的形成。