Synthesis and transformations of metallacycles 41. Cyclomagnesiation of O-containing 1,2-dienes with Grignard reagents in the presence of Cp2TiCl2

A Cp₂TiCl₂-catalyzed intermolecular homocyclomagnesiation of O-containing 1,2-dienes and cross-cyclomagnesiation of O-containing 1,2-dienes with aliphatic 1,2-dienes of cyclic and acyclic structure have been accomplished using Grignard reagents, which led to mono- and bicyclic organomagnesium compounds in 61–94% yields.     

Catalytic C−H Trifluoromethoxylation of Arenes and Heteroarenes

The intermolecular C?H trifluoromethoxylation of arenes remains a long‐standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox‐active catalysts for the direct (hetero)aryl C?H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy‐to‐handle reagents, requires only 0.03 mol % of redox‐active catalysts, does not need specialized reaction apparatus, and tolerates a wide variety of functional groups and complex structures such as sugars and natural product derivatives. Importantly, both ground‐state and photoexcited redox‐active catalysts are effective. Detailed computational and experimental studies suggest a unique reaction pathway where photoexcitation of the trifluoromethoxylating reagent releases the OCF₃ radical that is trapped by (hetero)arenes. The resulting cyclohexadienyl radicals are oxidized by redox‐active catalysts and deprotonated to form the desired products of trifluoromethoxylation.     

多氟烯烃和炔烃的钯催化氢化

本文报道Pd/Al_2O_3(1%)催化剂催化氢化CF_3CCl=CClCF_3,CF_3CCI==CHCF_3和CF_3C=CCF_3等多氟烯烃和炔烃的结果。经1~H和(19)~F核磁共振、质谱、红外等分析,证明了用制备色谱分离后的氢化产物主要成份的结构。前二者的氢化产物中主要是CF_3CH_2CH_2CF_3和CF_3CH_2CHClCF_3的混合物,而CF_3C=CCF_3氢化后只生成CF_3CH_2CH_2CF_3。     

亚硫酸四氟乙二醇酯的环断裂反应

含有亚硫酸四氟乙二醇酯(1)的四氟乙烷磺内酯(2)与H(CF_2)_4CH_2OH和三乙胺反应可获得草酸酯(CO_2CH_2CF_2CF_2—CF_2CF_2H)_2(3)。化合物(3)生成的机理解释为由于1的破环,生成了SOF_2和(COF)_2,后者进一步与H(CF_2)_4CH_2OH反应生成3。 3与二乙胺反应生成Et_2NCOCO_2CH_2(CF_2)_4H(4)。3和4皆为新化合物。     

Fluoroalkylation of Diazo Compounds with Diverse Rfn Reagents

Progress in the transition‐metal‐catalyzed or ‐free fluoroalkylation of diazo compounds with different types of fluoroalkyl (R_fn) transfer reagents is summarized in this review. Special attention is focused on the straightforward trifluoromethylation, gem‐difluoroolefination, trifluoromethoxylation, fluoroalkylthiolation, and trifluoromethylselenolation of diazo substrates. The mechanistic insights and the application of some of the products are also discussed in this article. We believe that this review will inspire both young and experienced chemists to further study the direct fluoroalkylation of diazo compounds as an efficient and convenient way to build complex fluorine‐containing molecules.     

一些长链全氟烷基化合物的19-FNMR化学位移

长链全氟烷基化合物的~(19)F NMR化学位移已有很多报道,然而,文献报道的大多是CF_3-(CF_2)_n-X化合物,对于X-(CF_2)_n-Y化合物报道相对较少。长链全氟烷基化合物的~(19)F NMR谱的归属是较困难的,特别是对于X-(CF_2)_n-Y的化合物的谱,由于两端取代基的效应,图谱归属更困难。本文报道一些未报道过的长链全氟烷基化合物的~(19)F NMR化学位移的数据,并讨论它们的归属。     

二氧化碳激光引发2-氯-1,1,1,2-四氟乙烷反应

本文研究了用TEA-CO_2激光和CW-CO_2激光以SF_6作为敏化剂引发CF_3CFHCl的反应。分析了CF_3CFHCl以及添加清除剂Cl_2,Br_2,O_2,的光解产物。结果表明CF_3CF:是初级产物,它很易重排成为CF_2—CF_2,或转化成CF_3CF—CF_2。在Cl_2或Br_2存在时,可生成CF_3CFCl_2或CF_3CFBr_2。此外,还讨论了反应机制。     

CF3I在强红外场下的多光子解离

本文用TEA CO_2激光9.6R(14)支作激发光源, 富里叶变换红外光谱仪作分析手段, NO, O_2作CF_3自由基的捕捉剂, 研究了CF_3I红外多光子解离的动力学。实验发现, O_2和NO均可用来捕捉CF_3I的红外光解产物CF_3自由基。从对CF_3I的红外多光子解离率与外加气体压力的变化关系的研究, 以及CF_3I红外多光子吸收的测量, 揭示出该分子在受红外激光激发时, 具有小分子的特性。同时也观察到外加气体对早期瓶颈效应的消除。在无碰撞及早期瓶颈效应可忽略状态下, 用能量间隔主方程对多光子解离率与激光能量密度的变化关系作了拟合, 得出了与实验比较一致的结果。     

Silver‐Promoted Oxidative Benzylic C−H Trifluoromethoxylation

A silver‐promoted oxidative benzylic C?H trifluoromethoxylation has been reported for the first time. With trifluoromethyl arylsulfonate as the trifluoromethoxylation reagent, various arenes, having diverse functional groups, undergo trifluoromethoxylation of their benzylic C?H bonds to form trifluoromethyl ethers under mild reaction conditions. In addition, the trifluoromethoxylation and the fluorination of methyl groups of electron‐rich arenes have been achieved to prepare α‐fluorobenzyl trifluoromethyl ethers in one step.     

Visible‐Light Photoredox‐Catalyzed and Copper‐Promoted Trifluoromethoxylation of Arenediazonium Tetrafluoroborates

We report the development of photoredox‐catalyzed and copper‐promoted trifluoromethoxylation of arenediazonium tetrafluoroborates, with trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxylation reagent. This new method takes advantage of visible‐light photoredox catalysis to generate the aryl radical under mild conditions, combined with copper‐promoted selective trifluoromethoxylation. The reaction is scalable, tolerates a wide range of functional groups, and proceeds regioselectively under mild reaction conditions. Furthermore, mechanistic studies suggested that a Cs[Cu(OCF₃)₂] intermediate might be generated during the reaction.     

Trifluoromethoxylation of Arenes: Synthesis of ortho‐Trifluoromethoxylated Aniline Derivatives by OCF3 Migration

Aryl trifluoromethoxylation by a two‐step sequence of O‐trifluoromethylation of N‐aryl‐N‐hydroxylamine derivatives and intramolecular OCF₃ migration is presented. This protocol allows easy access to a wide range of synthetically useful ortho‐OCF₃ aniline derivatives. In addition, it utilizes bench‐stable reagents, is operationally simple, shows high functional‐group tolerance, and is amenable to gram‐scale as well as one‐pot synthesis. A reaction mechanism of a heterolytic cleavage of the N? OCF₃ bond followed by recombination of the resulting nitrenium ion and trifluoromethoxide is proposed for the OCF₃‐migration reaction.     

一种新型哒嗪与N-戊烷基咔唑类聚合物的合成与表征

以二氯-1,3-双(二苯基磷)丙烷基镍(Ⅱ)为催化剂,通过3,6-二氯哒嗪格氏试剂与3,6-二溴-N-戊烷基咔唑共聚得到了一种新型共轭聚合物,并使用IR和1H-NMR等测试手段对单体和聚合物的结构进行了表征。该合成方法所得的共聚物收率为75%,共聚物在N,N-二甲基酰胺(DMF)、二甲基亚砜(DMSO)等极性溶剂和CF3COOH、CH3SO3H、HCOOH等常用有机酸中具有较好的溶解性。用红外(FT-IR)、紫外-可见吸收光谱(UV-vis)、荧光光谱(PL)、X射线衍射、循环伏安(CV)等对聚合物的吸收光谱特性、结晶性和电化学活性进行了探讨。结果表明:聚合物具有较高的发光强度,是一种还原型聚合物,结晶性比较差。     

Recent Development of Catalytic Trifluoromethoxylation Reactions

Trifluoromethoxy (OCF₃) group exhibits unique properties, which render it a highly desirable structural motif in life and materials sciences. The numbers of newly synthesized trifluoromethyl ethers are booming as new synthetic methods are constantly being developed to access these valuable compounds. This Review summarizes recent catalytic approaches towards preparation of trifluoromethyl ethers. Alkene, allylic, benzylic, and aryl trifluoromethoxylation reactions are discussed herein.     

Direct Dehydroxytrifluoromethoxylation of Alcohols

The first example of a direct dehydroxytrifluoromethoxylation of alcohols has been developed. This method generated an alkyl fluoroformate in situ from alcohols, followed by nucleophilic trifluoromethoxylation with trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxylation reagent. The reaction is operationally simple and scalable, and it proceeds under mild reaction conditions to provide access to a wide range of trifluoromethyl ethers from alcohols. In addition, this method is suitable for the late‐stage trifluoromethoxylation of complex small molecules.     

激光引发二氟卡宾与烯烃的反应

近十年来,激光引发一氯二氟甲烷红外多光子解离和激光敏化反应的研究非常活跃,但大部分工作都集中于解离机制及同位素分离,而对CF_2HC(?)多光子解离产生的二氟卡宾     

Copper-Catalyzed Enantioselective Trifluoromethoxylation of Propargyl Sulfonates

Due to the strong electron-withdrawing nature and high lipophilicity of trifluoromethoxy group (OCF₃), methods for introducing OCF₃ into organic molecules are in high demand. However, the research area of direct enantioselective trifluoromethoxylation is still in the embryonic stage, with limited enantioselectivity and/or reaction types. Here, we describe the first copper-catalyzed enantioselective trifluoromethoxylation of propargyl sulfonates using trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxy source in up to 96 % ee.     

Cobalt-Catalyzed α-Arylation of Substituted α-Bromo α-Fluoro β-Lactams with Diaryl Zinc Reagents: Generalization to Functionalized Bromo Derivatives

A cobalt-catalyzed cross-coupling of α-bromo α-fluoro β-lactams with diarylzinc or diallylzinc reagents is herein disclosed. The protocol proved to be general, chemoselective and operationally simple allowing the C4 functionalization of β-lactams. The substrate scope was expanded to α-bromo lactams and amides, α-bromo lactones and esters as well as N - and O-containing heterocycles.     

CF3CO和CF3C（O）O自由基分解反应理论研究

利用文献结果，用统计热力学和过渡态理论计算了ＣＦ３ＣＯ和ＣＦ３Ｃ（Ｏ）Ｏ自由基分解反应的热力学和动力学数据。计算结果表明，计算值与最新实验数据甚相符合，并据此判断，ＣＦ３ＣＯ和ＣＦ３Ｃ（Ｏ）Ｏ均很不稳定，不可能参加Ｏ３分解的循环催化反应。     

新型气相色谱固定液-聚全氟醚三嗪

聚全氟烷基三嗪(1)具有耐高温、耐氧化和耐酸等特性,可作为气相色谱固定液。它不仅可以分离有机氟化合物如含氟磺酰氟、磺酸酯等,而且也适用于同时含有氯、溴、碘的有机氟化合物。     

CF2HCl分子在红外多光子解离时分子间的能量传递过程

The infrared multiphoton dissociation (IR MPD) of CF_2HCl by measuring the C_2F_4 product after laser irradiation is investigated, The dissociation fraction of CF_2HCl as a function of the CF_2HCl pressure, laser energy fluence and number of laser pulses is measured. Under the low pressure condition the bottleneck effect is observed. Under the collision condition the dissociation fraction of CF_2HCl is affected by the competition between rotaional hole filling (collisional repoputation of pumped rotational states) and collisional deactivation of excited CF_2HCl moleculae.