单氟甲基化反应的研究进展

有机氟化物在医药、农业化学等领域发挥着不可缺少的作用,其中,氟甲基官能团具有较强的的亲脂性,可以极大地改善药物分子的药代动力学性质.因此,开发各类氟化反应具有重要的价值,尤其向分子中引入单氟甲基在氟化学领域备受关注.针对不同结构分子的单氟甲基化,按照氟甲基试剂分类总结单氟甲基化反应的研究进展,并对部分反应可能的机理进行讨论.     

铜促进的三氟甲基化反应研究进展

药物分子中含有三氟甲基可以有效改善其亲脂性、可吸收性以及代谢稳定性.因此,在有机分子中引入三氟甲基引起了人们的广泛关注.近年来,过渡金属催化的三氟甲基化反应得到了快速发展.其中,铜作为一种廉价且活性较高的催化剂能够实现多种三氟甲基化反应.从发生三氟甲基化反应的底物出发,综述了近年来卤代烃、硼试剂、C—H化合物、胺类、羧酸类化合物等的三氟甲基化反应研究进展.     

烯烃类衍生物的碘三氟甲基化反应

在ZnI2为催化剂,Togni试剂为三氟甲基化试剂,CHCl3为溶剂的条件下,以中等收率(30%~65%)实现烯烃的碘三氟甲基化反应,合成了一系列既含碘又含三氟甲基的酯类、酮类、酰胺类、腈类等化合物,其结构经1H NMR,13C NMR,19F NMR,IR,MS和HR-MS表征。其中4,4,4-三氟-2-碘丁酰胺,4,4,4-三氟-2-碘-N,N-二甲基丁酰胺和6,6,6-三氟-4-碘-3-己酮为新化合物。     

经由三氟甲基自由基的三氟甲基化反应研究进展

含有三氟甲基的有机分子在功能材料、农业化学品、制药等领域具有广泛应用,发展三氟甲基化的新方法是有机化学中的热点．通过产生三氟甲基自由基形成碳碳键是三氟甲基化的重要策略．本文依据三氟甲基自由基产生的不同方式,分3部分介绍三氟甲基自由基经由的碳碳键形成反应．     

可见光促进的双键三氟甲基化反应研究

报道了一种可见光促进的双键直接三氟甲基化的方法.研究中利用Ru（bpy）₃Cl₂为催化剂,Togni's试剂为三氟甲基来源,在可见光促进下实现了含羰基烯烃的三氟甲基化.该反应具有方法简便,条件温和,可以获得较高的反应收率,同时避免了有毒试剂的使用.     

CF3Br参与的三氟甲基化反应研究进展

三氟甲基化反应是向有机物中引入氟原子的重要方法.综述了近年来以CF₃Br为三氟甲基源的三氟甲基化反应研究进展,重点介绍了各类反应涉及到的具体方法、每种方法的特点、适用范围及可能的机理,并对CF₃Br作为三氟甲基源的三氟甲基化反应前景作出展望.     

从三氟甲基化反应的近年进展看有机氟化学的发展趋势

由于含三氟甲基的化合物在医药、农药等领域得到广泛应用,发展向有机分子引入三氟甲基的方法成为当前的热点研究课题.分别总结了国外和我国学者近年(主要是2009～2011年)在三氟甲基化反应研究领域取得的研究成果.从近年三氟甲基化反应的研究进展,作者提出一些值得关注的有机氟化学发展方向.     

可见光促进下氟烷基砜对芳基烯烃的自由基氟烷基化反应

自由基氟烷基化是向有机分子中引入氟烷基的一类非常重要的方法,也是目前有机化学研究的热点之一.近几年来,由于广泛的官能团兼容性和温和的反应条件等优点,可见光促进的氧化还原催化反应得到了长足的发展,已经成为化学键的构建和活化的有力工具.因此,光氧化还原催化的自由基氟烷基化反应,作为向有机化合物中引入氟烷基的有效途径,受到了广泛关注.本文报道了我们发展的氟烷基砜作为一类方便易得的新型氟烷基自由基前体,在可见光氧化还原催化下实现对烯烃的自由基氟烷基化反应.该反应可以高效地向芳基烯烃中引入三氟甲基、二氟甲基、1,1-二氟乙基、苯基二氟甲基等各种含氟烷基基团,并实现对芳基烯烃的双官能团化转化.     

铜催化烯醚的三氟甲基化反应

在溴化亚铜和醋酸亚铜的共同作用下,成功实现了烯醚的三氟甲基化反应.该反应为2-三氟甲基烯醚类化合物的合成提供了一条潜在的合成途径.该反应条件温和,收率良好,并且具有很好的官能团容忍性.产物结构经NMR,IR,MS及HRMS数据得以证实.     

Recent Advances in Trifluoromethylation Reactions with Electrophilic Trifluoromethylating Reagents

Electrophilic trifluoromethylation reactions have been the latest approach to achieve the fluoroalkylation of compounds with newly‐discovered reagents, such as the Togni’s (1‐trifluoromethyl‐1,2‐benziodoxol‐3‐(1 H)‐one), Umemoto’s (S‐(trifluoromethyl)dibenzothiophenium tetrafluoroborate), Yagupolskii’s (S‐(trifluoromethyldiarylsulfonium salts), Shreeve’s (S‐(trifluoromethyl)dibenzothiophenium triflate), and Shibata’s (trifluoromethylsulfoximine salts) reagents. All these reagents produce an electrophilic trifluoromethylating (CF₃⁺) species that undergoes reaction with nucleophiles. In addition, these latter reactive species (i.e. CF₃⁺) can undergo electron‐transfer (ET) processes affording CF₃ ^? radicals that expand the scope to substrates other than conventional nucleophiles that can undergo reaction. In this Review, we shall discuss the trifluoromethylation reactions of diverse families of organic substrates of biological interest as a means to comparing the reagents scope and best reaction conditions. Some, though not all, of these reactions require the assistance of metal or organometallic catalysts. Some require additives and catalysts to promote the fluoroalkylation reaction, but invariably all are initiated and carried out by electrophilic trifluoromethylating species.     

可见光促进的光氧化还原催化的三氟甲基化反应

全氟烷基化反应,特别是三氟甲基化反应一直是有机化学领域的研究热点。近几年来,可见光促进的光氧化还原催化的有机化学反应,因其本身所固有的条件温和、绿色和环保等优点而倍受合成化学家的青睐。该方法学也被成功地应用于一系列三氟甲基化反应。本文主要按照三氟甲基源分类,总结了近年来可见光促进的光氧化还原催化的三氟甲基化反应的研究进展,并对其发展趋势进行了展望。     

催化不对称光诱导自由基反应

自由基反应的立体选择性调控一直是不对称催化领域的挑战性难题.近年来,光化学过程特别是可见光化学过程在有机合成中越来越受到研究人员的重视,光诱导自由基化学也再次进入人们的视野.相对传统的自由基化学,光诱导自由基化学反应条件温和,易于调控,为实现高效催化不对称自由基反应带来了新的契机,展示了蓬勃的发展潜力.本文根据光诱导产生自由基种类的不同,简要介绍最近该方向的研究进展.     

Trifluoromethanesulfonic Anhydride as a Low‐Cost and Versatile Trifluoromethylation Reagent

A large number of reagents have been developed for the synthesis of trifluoromethylated compounds. However, an ongoing challenge in trifluoromethylation reaction is the use of less expensive and practical trifluoromethyl sources. We report herein the unprecedented direct trifluoromethylation of (hetero)arenes using trifluoromethanesulfonic anhydride as a radical trifluoromethylation reagent by merging photoredox catalysis and pyridine activation. Furthermore, introduction of both the CF₃ and OTf groups of the trifluoromethanesulfonic anhydride into internal alkynes to access tetrasubstituted trifluoromethylated alkenes was achieved. Since trifluoromethanesulfonic anhydride is a low‐cost and abundant chemical, this method provides a cost‐efficient and practical route to trifluoromethylated compounds.     

Recent Advances in Transition Metal‐Catalyzed Asymmetric Radical Reactions

Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively controlling sophisticated synthetic routes, great improvements in this filed have been achieved by merging transition‐metal asymmetric catalysis with radical chemistry. Herein we provide a perspective of some of the most significant contributions in the field during the past decades. Accordingly, the major advances are classified based on different strategies for controlling stereoselectivity including: (1) chiral metal complex chelation, (2) chiral metal complex combined with radical species and reductive elimination, (3) chiral metal complex outer‐sphere substitution by radical intermediate. Brief discussion of mechanism is presented whenever relevant.     

Recent Developments in the Trifluoromethylation of Alkynes

In the last few years, the development of versatile methodologies to incorporate trifluoromethyl groups into organic molecules has attracted significant attention in synthetic chemistry. This review gives an overview over the development on the trifluoromethylation of alkynes, which have not been solely discussed before. Formation of diverse C(sp, sp², sp³)?CF₃ bonds are all covered in this review.     

Efficient Cu‐catalyzed Atom Transfer Radical Addition Reactions of Fluoroalkylsulfonyl Chlorides with Electron‐deficient Alkenes Induced by Visible Light

Fluoroalkylsulfonyl chlorides, R_fSO₂Cl, in which R_f=CF₃, C₄F₉, CF₂H, CH₂F, and CH₂CF₃, are used as a source of fluorinated radicals to add fluoroalkyl groups to electron‐deficient, unsaturated carbonyl compounds. Photochemical conditions, using Cu mediation, are used to produce the respective α‐chloro‐β‐fluoroalkylcarbonyl products in excellent yields through an atom transfer radical addition (ATRA) process. Facile nucleophilic replacement of the α‐chloro substituent is shown to lead to further diverse functionalization of the products.     

Recent Advances in Photochemical Asymmetric Three-Component Reactions

Over the past decades, asymmetric photochemical synthesis has garnered significant attention for its sustainability and unique ability to generate enantio-enriched molecules through distinct reaction pathways. Photochemical asymmetric three-component reactions have demonstrated significant potential for the rapid construction of chiral compounds with molecular diversity and complexity. However, noteworthy challenges persist, including the participation of high-energy intermediates such as radical species, difficulties in precise control of stereoselectivity, and the presence of competing background and side reactions. Recent breakthroughs have led to the development of sophisticated strategies in this field. This review explores the intricate mechanisms, synthetic applications, and limitations of these methods. We anticipate that it will contribute towards advancing asymmetric catalysis, photochemical synthesis, and green chemistry.     

Controlled Trifluoromethylation Reactions of Alkynes through Visible‐Light Photoredox Catalysis

The control of a reaction that can form multiple products is a highly attractive and challenging concept in synthetic chemistry. A set of valuable CF₃‐containing molecules, namely trifluoromethylated alkenyl iodides, alkenes, and alkynes, were selectively generated from alkynes and CF₃I by environmentally benign and efficient visible‐light photoredox catalysis. Subtle differences in the combination of catalyst, base, and solvent enabled the control of reactivity and selectivity for the reaction between an alkyne and CF₃I.