多环芳烃与不饱和自由基氢提取反应类的动力学研究

对2~6个环的多环芳烃的氢提取反应类进行了系统研究, 提取氢原子的不饱和自由基包括丙炔基自由基（C₃H₃）、 烯丙基自由基（C₃H₅）、 丁二烯基自由基（nC₄H₅, iC₄H₅）、 环戊二烯基自由基（C₅H₅）以及苯基自由基（C₆H₅）. 采用M06-2X/cc-pVTZ方法得到了多环芳烃的电子结构信息, 利用过渡态理论并结合Eckart隧道校正, 计算了所有反应在500~2500 K范围内的反应速率常数.考察了多环芳烃的大小、 结构对反应速率常数的影响, 对比了不同氢提取自由基及不同氢提取反应类型的速率常数. 结果表明, 多环芳烃的大小对反应速率常数影响不大, 但是多环芳烃的环结构对反应速率常数影响较大. 将不同的氢提取反应类简化为发生在五元环上的C₅类和发生在六元环上的C₆类两类, 结果表明, C₆类的反应活性高于C₅类. 研究了nC₄H₅, iC₄H₅以及C₆H₅自由基与多环芳烃的氢提取反应, 它们的氢提取反应活性大小顺序为C₆H₅>nC₄H₅>iC₄H₅. 通过对每类典型反应的速率常数取平均值, 总结出相应类型的速率规则, 可用于构建多环芳烃和碳烟机理.     

基于[3+2]环加成反应的氮杂螺[3,4]环辛烷的合成

哌嗪、吗啉是小分子药物中常见的结构片段,2,6-二氮杂螺[3,4]环辛烷和2-氧-6-氮杂螺[3,4]环辛烷等四元螺环化合物作为其类似物,在药物化学领域具有良好的应用前景.本研究以廉价易得的丙二酸二乙酯或丙烯酸乙酯为起始原料,经[3+2]环加成反应,可便捷高效地完成6-苄基-2,6-二氮杂螺[3,4]环辛烷和2-氧-6-氮杂螺[3,4]环辛烷克级水平的合成.     

高张力笼形氮杂环化合物的合成

以六苄基六氮杂异伍兹烷(HBIW)为母体,Pd(OH)₂/C为催化剂,在温和条件下,通过选择性催化氢解脱苄,使部分或全部苄基被其它官能团(如CH₃O-,C₂H₅-,CHO-)取代,合成了4种N-取代六氮杂异伍兹烷,并鉴定了它们的结构.这些化合物都是高张力的笼形氮杂环化合物,且均可作为合成六硝基六氮杂异伍兹烷(HNIW)的前体,而HNIW是当今最引人注目和最有军用前景的高能量密度化合物(HEDC).     

二环戊二烯基二芳基铪化合物的研究

Rausch等报道由二环戊二烯基二氯化铪与五氟苯基锂在低温、乙醚中按下式反应,得到含σ-碳-铪键的二环戊二烯基二(五氟苯基)铪:(η⁵-C₅H₅)₂HfCl₂+2C₆F₅Li→(η⁵-C₅H₅)₂Hf(C₆F₅)₂+2LiClSamuel等用同样反应合成了二环戊二烯基二苯基铪.     

光催化苄基邻卤芳醚与CO2的连续去芳构化/羧化反应合成螺环羧酸(英文)

自1900年首次发现螺环化合物以来,由于它在药物分子、手性配体、激光染料等领域的重要作用,越来越多的螺环化合物被发现和研究.目前已研发出了几种典型的反应来合成螺环化合物,如分子间的环加成或偶联反应及双官能团化合物分子内的偶联反应.但这些方法仍存在选择性难以控制、螺环中官能团耐受性差、条件苛刻等不足.因此,有必要发展合成含各类官能团的螺环的方法.近年来,芳基化合物的分子内去芳构化已经成为合成螺环骨架的有效策略,尤其是通过光催化去芳构化合成螺环.CO₂作为C1合成子具有丰富、低成本、可持续及无毒等优势,若将CO₂作为羧酸源键联在螺环骨架上,将有可能构建具有潜在生物活性的螺环羧酸衍生物.基于本课题组对光催化CO₂转化利用反应的持续研究,本文设计开发了一种合成螺环羧酸化合物的便捷方法,即光催化苄基邻卤芳醚与CO₂的连续去芳构化/羧化反应.根据条件筛选实验结果,最终选择1,2,3,5-四(咔唑-9-基)-4,6-二氰基苯(4Cz IPN)作为光敏剂, N,N-二异丙基乙基胺(DIPEA)为还原剂,叔丁醇钠作为...     

活性氮与碘乙烷反应化学发光研究

在流动余辉装置上, 利用N₂空心阴极放电制备活性氮, 研究了活性氮与碘乙烷(C₂H₅I)反应的化学发光. 在620～820 nm波长范围内观察到了较强的发射光谱, 拟合得到的光谱常数表明它来源于NI(b¹Σ^＋→X³Σ^－)跃迁, 并对35个谱峰进行了振动归属. 最后讨论了活性氮中主要成分与C₂H₅I反应的可能过程, 结合辅助性实验分析表明, 活性氮中的N(²P)与C₂H₅I直接反应很可能产生激发态NI(b¹Σ^＋)自由基. 这是利用化学反应直接产生激发态NI(b¹Σ^＋)的首次报道, 观察到的激发态最高振动能级为v'＝6.     

氧杂三螺环化合物的简便合成

以环酮和季戊四醇为原料,磷钨酸为催化剂,在甲苯中回流分水反应合成了系列氧杂三螺环化合物（3a~3h）,其中5,9,14,17-四氧杂三螺［3.2.2.3¹⁰.2⁷.2⁴］十七烷（3a）和7,11,18,21-氧杂-3,15-二硫杂三螺［5.2.2.5¹².2⁹.2⁶］二十一烷（3f）为新化合物,其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。并以3c的合成为模板反应,对反应条件进行了优化。     

基于氟烷基自由基过程构建手性中心的研究进展

含氟的有机化合物被广泛地应用于制药、农业化学品、材料科学等多个领域.三氟甲基、二氟甲基、全氟烷基等是应用非常广泛的含氟官能团,因此发展普适高效的引入氟烷基的新方法具有重大意义.氟烷基自由基反应近年来已经发展成为引入氟烷基的有效方法.另一方面,氟烷基取代的手性有机分子的合成也受到了人们的重点关注.然而由于氟烷基自由基的高反应活性,其反应的选择性较难控制,特别是关于对映选择性控制的报道不多,更缺乏相关综述予以总结.综述了近二十年来基于氟烷基自由基过程的不对称合成方法的研究进展,对各反应的选择性、普适性、反应机理等方面进行着重介绍.本综述根据反应机理分为三部分:(1)经由氟烷基自由基的烯醇/烯胺中间体不对称氟烷基化;(2)经由氟烷基自由基的烯烃不对称双官能团化;(3)经由氟烷基自由基的烯基硼酸酯酸根型复合物立体选择性1,2-迁移.     

含吡啶环系西佛碱大环配合物和氮杂大环自由配体的合成

2, 6-二羟甲基吡啶(1)经活性MnO~2氧化得到2, 6-二甲酰基吡啶(2)。邻硝基苯酚与N-取代的二(氯乙基)胺在DMF溶液中反应, 得到N-取代的1, 5-二(邻硝基苯氧基)-3-氮杂戊烷(3a～3c), 再经水合肼/Raney Ni还原, 获得N-取代的1, 5-二(邻氨基苯氧基)-3-氮杂戊烷(4a～4c)。利用Ba^2^+作为模板离子, (2)分别与(4a～4c)反应, 合成了一类新的含吡啶环系西佛碱大环配合物I-III, 配合物I、III与NaBH~4的乙醇溶液还原解络, 得到氮杂大环自由配体IV和V。所有西佛碱大环配合物和氮杂大环自由配体均经元素分析、IR、^1H NMR、MS等证实了它们的结构和组成。     

可见光诱导烯烃环化合成二氟烷基化异喹啉二酮

发展了一种可见光诱导的活泼烯烃串联自由基环化合成含氟异喹啉二酮的反应。 在可见光诱导下,多种N-烷基-N-甲基丙烯酰基苯甲酰胺与二氟溴乙酸乙酯发生自由基串联环化反应,以66%~75%的产率合成了一系列具有潜在生理活性的二氟烷基化异喹啉二酮。 此研究为合成具有潜在药用价值的氟取代异喹啉二酮提供了一条高效、条件温和的途径。     

Photochemistry of perfluoroacyl halides in the presence of O2 and CO

Photolyses of CF₃C(O)X and C₂F₅C(O)X (X=Cl, F) at 254 nm in the presence of O₂ yield the perfluorinated radicals C₂F₅O (C₂) and CF₃O (C₁), respectively. The C₂ radicals decompose to give CF₃ radicals:

C₂F₅O→CF₃+CF₂O

which, in turn, react with O₂ leading to the formation of C₁ radicals. When in addition to O₂, CO is present, the C₁ radicals react with it leading to its catalytic oxidation to CO₂. The trioxide CF₃OC(O)O₃C(O)OCF₃ was observed following the photolysis of all four halides in the presence of O₂ and CO.

The other radical partners coming from the initial step in the photolysis (XC(O)) as well as the products of their reaction with O₂ (XC(O)O_y, y=1, 2) do not react with CO but when X=F they lead to the formation of a new stable peroxy molecule with the formula CF₃OC(O)O₂C(O)F. Some of the properties of this new molecule, its stability and its IR features are presented in this work.     

Theoretical Exploration of Stereochemical Nonrigidity for RfCo（PF3）x（CO）4-x（Rf=CF3, C2F5, C3F7, x=0-4）

The stereochemical nonrigidity of RfCo（PF3）x（CO）4-x（Rf=CF3,C2F5,C3F7,x=0-4） was studied at the theoretical level of B3LYP/6-31 1＋G^＊ via Gaussian 09.The intramolecular rearrangements in these penta-coordinated compounds are mainly caused by the vibrations of perfluoroalkyl groups.All the barriers along the reaction coordinate are less than 66.9 kJ/mol,which indicates that the rearrangements are kinetically favorable and hard to elucidate by experiment.Besides,ligand PF3 is a ligand similar to CO,the energy difference between the reactant and product is small.     

Fluorescence of CF2(B1, 040,K'' = 9) excited by the 253.7 nm Hg resonance line

Resonance fluorescence spectra of CF₂(¹B₁, 040, K' = 9) excited at 253 7 nm have been observed in the photolysis of C₂F₄ using a low-pressure mercury lamp. At low C₂F₄ pressures, the spectra with a series of doublet hands from 254 to 400 nm were consistent with the transitions from ¹B₁, 040, K'=9 to ¹A₁, 0v'₂0, K' = 8, 10, and also to ¹A₁, 1v'₂0, K' = 8, 10 The appearance of doublet bands (Δ K = ±1) provides clear evidence that the transition is of the perpendicular type.     

Synthesis and characterization of hydroxo, pyrazolato and carboxylato derivatives of the PdR(PPh3)moiety (R = C6F5 or C6Cl5)

The hydroxo-complexes [{PdR(PPh₃)(μ-OH)}₂] (R = C₆F₅ or C₆Cl₅) have been obtained by reaction of the corresponding [{PdR(PPh₃)(μ-Cl)}2] complexes with NBu₄OH in acetone. In this solvent, the reaction of the hydroxo-bridged complexes with pyrazole (Hpz) and 3,5-dimethylpyrazole (Hdmpz) in 1:2 molar ratio leads to the formation of the new complexes [{Pd(C₅F₅)(PPh₃)(μ-azolate)}2] and [{Pd(C₆Cl₅)(PPh₃)}₂(μ-OH)(μ-azolate)] (azolate = pz or dmpz). The reaction of the bis(μ-hydroxo) complexes with Hpz and Hdmpz in acetone in 1:1 molar ratio has also been studied, and the resulting product depends on the organic radical (C₆F₅ or C₆Cl₅) as well as the azolate (pz or dmpz). The identity of the isomer obtained has been established in every case by NMR (¹H, ¹⁹F and ³¹P) spectroscopy. The reaction of the bis(μ-hydroxo) complexes with oxalic (H₂Ox) and acetic (HOAc) acids yields the binucle ar complexes [{PdR(PPh₃)}2(μ-Ox)] (R = C₆F₅ or C₆Cl₅) and [{Pd(C₆F₅)(PPh₃)(μ-OAc)}2], respectively. [{Pd(C₆F₅)(PPh₃)(μ-OH)}₂] reacts with PPh₃ in acetone in 1:2 ratio giving the mononuclear complex trans-[Pd(C₆F₅) (OH)(PPh₃)₂], whereas the pentachlorophenylhydroxo complex does not react with PPh₃, even under forcing conditions.     

Novel perfluoroalkenylphosphonates and iodoperfluoroalkenes from 3,3 -bis (trifluoromethyl) -1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene

The reaction of 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene with tris(trimethylsilyl)phosphite gave fluorotrimethylsilane and the respective (Z)-alkenylbis(trimethylsilyl)phosphonates. In one case hydrolysis afforded the free phosphonic acid (CF₃)₃CCF = CFP(O) (OH)₂. Using tri-n-butylphosphine and boron trifluoride etherate, 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro-n-butoxy-1,1,2-trifluoroethylene were converted into the corresponding phosphonium tetrafluoroborates, which when reacted further with iodine in the presence of Na₂CO₃ gave the iodo derivatives (CF₃)₃CCF = CFI and C₄F₉OCF = CFI.     

Fluoride ion-mediated nucleophilic fluoroalkylation of alkyl halides with Me3SiCF2SPh: Synthesis of PhSCF2- and CF2H-containing compounds

A facile and highly efficient nucleophilic (phenylthio)difluoromethylation of alkyl halides has been achieved via fluoride ion-mediated substitution reaction using [difluoro(phenylthio)methyl]trimethylsilane (Me₃SiCF₂SPh). The reaction proceeds well with primary alkyl bromides (or alkyl iodides) in DME solvent when CsF/15-crown-5 was used as the fluoride source/additive. The PhSCF₂-containing products can be readily transformed into CF₂H-containing compounds via a free-radical desulfurization method.     

Radical additions to fluoro-olefins. photochemical mono-fluoroalkylation and sequential bis-fluoroalkylation of oxolane

Oxolane was fluoroalkylated by its photoadditions under atmospheric pressure. Monofluoro-alkylations were carried out with hexafluoropropene (1) and perfluorovinyl ethers C₃F₇O-[CF(CF₃)CF₂O]_n-CF = CF₂ (24, n = 0–2) by direct photoexcitation of the olefins to give high yields of addition products 9–12 (81–94%). The reactions were completely regioselecti ve at the oxolane molecule and almost completely regioselective (93–99%) at the double bond of fluoro-olefins; no bis-fluoroalkylated oxolanes were detected. The completely selective introduction of a second fluoroalkyl into position 5 of the oxolane molecule was accomplished by acetone-sensitised photoaddition of 2fluoroalkylated oxolanes 9,10 to fluoro-olefins 1 and 2. Byproducts from reactions of the dimethylketyl radical which is formed in the initiation step were isolated and have given some evidence about the reaction mechanism that is discussed.     

Synthesis, structure and reactivity of [(CF3)3GePt(PPh3)2]2Hg

The reaction of Pt(PPh₃)_n (n = 3 or 4) with [(CF₃)₃Ge]₂Hg or (CF₃)₃GeHgPt(PPh₃)₂Ge(CF₃)₃ (I) gives a stable diplatinum complex [(CF₃)₃GePt(PPh₃)₂]₂Hg (II). X-Ray analysis has established that compound II contains a Ge---Pt---Hg---Pt---Ge chain of C₂ symmetry. Both of the Pt atoms have distorted square-planar coordinations. The bond lengths are: Pt---Hg, 2.630(2) and 2.665(2) Å; Ge---Pt, 2.410(4) and 2.407(4) Å.

Compound II reacts with dihydrogen in THF solution under mild conditions to give mercury and the hydride (CF₃)₃GePt(PPh₃)₂H. On interaction of II with R₂Hg organomercurials (R = Cl, Et, GeEt₃, Ge(CF₃)₃, Ge(C₆F₅)₃) an unknown reaction takes place: Pt(PPh₃)₂ moieties migrate from the polymetallic grouping into the substrate with the formation of the corresponding RHgPt(PPh₃)₂R complexes or their demercuration products, R₂Pt(PPh₃);, (R = Cl, Et). The latter react further with complex I formed in the first step of the process to give Hg and (CF₃)₃GePt(PPh₃)₂R. The reaction schemes are discussed.     

Homo- and hetero-bridged mixed-valence dinuclear complexes which contain the fragment ‘Rh(C6F5)3’

The reaction of the anionic mononuclear rhodium complex [Rh(C₆F₅)₃Cl(Hpz)]^t- (Hpz = pyrazole, C₃H₄N₂) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C₆F₅)₃Rh(μ-Cl)(μ-pz)M(L₂)] [M = Rh, L₂ = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO)₂ (4); M = Ir, L₂ = COD (3)]. The complex [Rh(C₆F₅)₃(Hbim)]⁻ (5) has been prepared by treating [Rh(C₆F₅)₃(acac)]⁻ with H₂bim (acac = acetylacetonate; H₂bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C₆F₅)₃Rh(μ-bim)M(L₂)]⁻ [M = Rh, L₂ = COD (6) or TFB (7); M = Ir, L₂ = COD (8); M = Pd, L₂ = η³-C₃H₅ (9)]. With [Rh(acac)(CO)₂], complex 5 yields the tetranuclear complex [{(C₆F₅)₃Rh(μ-bim)Rh(CO)₂}₂]₂₋. Homodinuclear Rh^III derivatives [{Rh(C₆F₅)₃}₂(μ-L)₂]^·- [L₂ = OH, pz (11); OH, S^tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C₆F₅)₃(μ-OH)}₂]²⁻ by the corresponding ligands. The reaction of [Rh(C₆F₅)₃(Et₂O)_x] with [PdX₂(COD)] produces neutral heterodinuclear compounds [(C₆F₅)₃Rh(μ-X)₂Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh₃⁺) salts.     

可见光诱导的共轭磺酰胺串联脱砜/环化反应

发展了一种可见光诱导的共轭磺酰胺串联脱砜/环化,合成全氟烷基化吲哚酮或α-芳基酰胺的方法。此反应以多氟烷基碘或溴为氟源,在发光二极管蓝光灯照射下,利用面式-三(2-苯基吡啶)合铱催化N-烷基-N-甲基丙烯酰基苯磺酰胺经过串联自由基加成/β-芳基迁移/脱砜环化过程,一步构筑两重碳-碳键,以41%~78%的产率合成了一系列含氟吲哚酮或α-芳基酰胺。此方法底物适用范围广,反应条件温和(室温),催化体系绿色,为具有潜在生理活性的含氟吲哚酮及α-芳基酰胺的合成提供了一条高效、快捷的新途径。