Selective and Non-selective Approach for Fluorination Reactions

醛和酮的三氟甲基化反应是一种将CF 3引入有机分子的潜在有效方法。通常，三氟甲基化反应通过在TBAF、TBAT、TMAF以及CsF引发下处理Me 3SiCF 3来进行。然而，这些可商购的氟化物相当昂贵且对湿气敏感。氟化钾（KF）是一种廉价且常用的氟化物源，也可用作三氟甲基化的引发剂，但该方法受到仅DMF可用作溶剂的显著限制。因此，新方法对于实验室规模以及大规模制备是高度期望的。我们希望报道一种方便的方法如下：1. KF/TBAB组合作为催化剂，用于醛、酮和酰亚胺在各种有机溶剂中的三氟甲基化，以良好至高产率提供三甲基硅烷基保护的α-三氟甲基醇。2.第一个刘易斯酸催化的醛与Me_3SiCF_3在TiF_4/DMF下的三氟甲基化反应，在Ti（OiPr）_4/DMF和Cu（OAc）_2/dppp/甲苯的条件下，我们成功地将此方法应用于Me_3SiCF_2SePh、Me_3SiCF_2P（O）OEt_2和Me_3SiCF_2SPh的醛的二氟甲基化反应。P（t-Bu）3-DMF体系能有效地促进反应。4.氟的选择性引入：氟甲基当量的氟代双（苯磺酰基）甲烷的单氟甲基化反应在重要化合物（S）-甲基氟代布洛芬和5-脱氧-5-氟-b-d-呋喃碳糖的合成中起着关键作用。关键步骤是钯催化的烯丙基单氟甲基化反应。

The trifluoromethylation of aldehydes and ketones is a potentially powerful method to introduce the CF3 moiety into organic molecules. In general, the trifluoromethylation reaction has been performed by treatment of Me3SiCF3 under initiation by TBAF, TBAT, TMAF as well as CsF. However, these commercially available fluorides are rather expensive and moisture sensitive. Potassium fluoride (KF) is an inexpensive and commonly used fluoride source and can be also used as an initiator for the trifluoromethylation, but the method suffers from the significant limitation that only DMF is available as a solvent. Therefore, novel methods are highly desirable for laboratory-scale as well as large-scale preparations. We wish to report a convenient procedure as follows.1.A KF/TBAB combination acts as a catalyst for trifluoromethylation of aldehydes, ketones, and imides in a variety of organic solvents to provide trimethylsilyl-protected a-trifluoromethyl alcohols in good to high yields.2.The first Lewis acid-catalyzed trifluoromethylation reactions of aldehydes with Me3SiCF3 under TiF4/DMF, Ti(OiPr)4/DMF and Cu(OAc)2/dppp/toluene conditions are described.We have successfully applied this methodology to the difluoromethylation of aldehydes using Me3SiCF2SePh, Me3SiCF2P(O)OEt2 and Me3SiCF2SPh.3.A truly catalytic nucleophilic trifluoromethylation reaction of carbonyl compounds with Ruppert's reagent, Me3SiCF3, has been shown to be efficiently promoted by a P(t-Bu)3-DMF system. Imines were also converted to the desired a-trifluoromethyl amines under similar reaction conditions.4.Selective introduction of fluorine : Monofluoromethylation with the fluoromethide equivalent fluorobis(phenylsulfonyl)methane was crucial in the syntheses of the pharmacologically important compounds (S)-methylfluorinated ibuprofen and 5-deoxy-5-fluoro-b-d-carbaribofuranose. The key step was a palladiumcatalyzed allylic monofluoromethylation reaction.