铟(I)/手性磷酸催化简单烯烃与β,γ-不饱和α-酮酸酯的不对称[4+2]环加成反应

报道了In（I）Cl/手性磷酸1a双酸体系催化的简单烯烃和β,γ-不饱和α-酮酸酯的不对称[4+2]环加成反应,可高产率、高选择性（最高99：1dr,99%ee）生成相应的exo-[4+2]环加成产物.InCl和磷酸的协同作用是反应成功的关键,单独使用InCl和磷酸都不能催化反应进行.     

HOMO活化的2-吡喃酮与2,5-二烯酮反电子需求的不对称Diels-Alder反应

2-吡喃酮的不对称Diels-Alder（DA）反应可以高效、高立体选择性地构建多官能团化的双环内酯手性骨架.目前贫电子的2-吡喃酮多依赖于手性Lewis酸通过降低LUMO能量与富电子烯烃发生反电子需求环加成反应,活化机制相对单一,因此发展新的活化模式合成此类骨架尤为重要.报道了在金鸡纳碱衍生的伯胺作用下,环状2,5-二烯酮能形成延伸型三烯胺中间体,从而活化远端δ,e-双键,与3-甲氧羰基-2-吡喃酮发生反电子需求不对称DA反应.该方法能够以中等到良好的收率（46%～82%）、优异立体选择性（93%～99%ee,>19∶1 dr）高效构建含有多个连续手性中心的双环内酯化合物.通过内酯醇解开环,能高收率进一步转化为手性环己烯醇化合物.我们发展的经HOMO活化的不对称反电子需求DA反应可以为构建手性双环内酯骨架提供一种较为实用的新方法.     

Lewis酸对氮杂环卡宾协同催化体系中反应途径的调控

该研究基于氮杂环卡宾（N-heterocyclic carbene,NHC）新颖的协同催化策略,通过Lewis酸共催化剂调控反应具体途径.从α,β-不饱和醛类化合物出发,立足于多反应位点的高烯醇中间体,与氯化镁协作实现高对映选择性的质子转移历程,构建β-手性酯类产物;在相似的反应体系中与氯化钌协作实现高效的空气氧化,构建α,β-不饱和酯类化合物.这两个迥异的反应途径对底物均有较好的官能团容忍性,以高转化率得到目标产物.     

手性路易斯碱和过渡金属协同催化反应的进展

近年来过渡金属与以苯并四咪唑类化合物为代表的手性路易斯碱协同作用下的不对称催化反应取得了重要的进展,包括芳基醋酸酯α衍生化及乙内酰脲、二氢喹啉酮等结构的合成、双手性中心烯丙基化反应和α-氨基酸衍生物合成等.这些反应在有机合成中有广阔的应用前景.本文将对这类反应的研究进展做简要的介绍.     

铜/手性磷酸催化烯烃不对称自由基胺芳基化

含β-芳基/α-季碳中心的吡咯烷是一类重要的手性吡咯烷类化合物.目前该类化合物的不对称合成主要是通过钯催化含氮烯烃底物与各类芳基前体的不对称胺芳基化反应来实现的.在这里报道了一种反应机理不同于上述反应的不对称胺芳基化新方法.利用本课题组之前发展的一价铜/手性磷酸组成的金属手性阴离子单电子催化体系成功实现了含氮烯烃底物与芳基重氮盐的不对称自由基的胺芳基化反应,以中等收率和中等至良好的对映选择性得到含β-芳基/α-季碳中心的吡咯烷类化合物.     

1,4-二烯和醛的烯丙基碳氢不对称烷基化反应

利用钯配合物、有机胺和手性布朗斯特酸三元催化剂体系实现了α-取代丙醛参与的1,4-二烯烃的烯丙基碳氢不对称烷基化反应,以良好的产率、优良的区域选择性和立体选择性得到了结构多样的手性α-羰基化合物.此外发现非手性膦配体对钯配合物的催化活性和反应的选择性有十分显著的影响,为后续相关研究提供了新的思路.     

有机催化靛红衍生酮亚胺与噁唑酮的不对称Mannich型加成反应

研究了手性磷酸催化的靛红衍生酮亚胺与噁唑酮的不对称Mannich型加成反应, 以良好至优秀的收率(高达97%)、 对映选择性(高达99% e.e.)以及非对映选择性(均>20∶1 d.r.)得到一系列含噁唑酮骨架的手性3,3′-二取代氧化吲哚化合物. 该反应可以进行扩大化和衍生反应.     

铑和手性螺环磷酸协同催化α-芳基重氮酮对醇的O-H键的不对称插入反应

过渡金属催化卡宾对O-H键的不对称插入反应是合成手性醇及其衍生物的直接方法.近年来,人们发展了多种手性催化剂实现了重氮酯衍生的金属卡宾对醇、酚、羧酸甚至水的O-H键的高对映选择性插入反应,但是重氮酮作为卡宾前体的不对称O-H键插入反应鲜有成功的例子.以非手性双铑络合物和手性螺环磷酸组成的协同催化体系,首次实现了α-重氮酮对醇的O-H键的不对称插入反应,获得了较高的收率和高达95%ee的对映选择性.反应为手性α-烷氧基酮这类重要手性化合物提供了高效的合成方法.还通过密度泛函理论计算,对反应机理进行了初步研究,发现水很可能参与了手性磷酸促进的烯醇中间体质子转移过程.     

不对称双酸催化3,4-二氢-2H-吡喃的反电子Hetero-Diels-Alder反应

研究了双酸催化剂不对称催化烯醚和β,γ-不饱和α-酮酸酯的反电子Hetero-Diels-Alder (HDA)反应, 为手性合成3,4-二氢-2H-吡喃类化合物提供了一种新的催化合成方法. InBr₃与手性磷酸钙盐Ca(1c)₂组合的手性双路易斯酸催化体系能够有效催化3,4-二氢-2H-吡喃和β,γ-不饱和α-酮酸酯的反电子HDA反应, 反应给出优秀的产率(最高达98%), 中等到良好的非对映选择性(最高达89:11)和良好到优秀的对映选择性(最高可达94%). 并且该双酸催化体系也能成功实现其它烯醚(如: 2,3-二氢-2H-呋喃, 乙烯基乙醚)的HDA反应, 获得优秀的非对映选择性(>94:6)和良好的对映选择性.     

推-拉电子体系环丙烷的不对称合成及其对映选择性开环/环化反应研究进展

含有推-拉电子(DA)体系的张力环化合物,例如DA环丙烷,是非常有用的合成砌块,被应用于天然产物全合成以及合成具有生物活性的分子的研究中。 近年来,本课题组利用手性铜、镍等配合物为催化剂,一方面发展了一系列高效合成手性DA环丙烷的新方法;另一方面陆续实现了仲胺、醇、硝酮、氮杂亚胺叶立德、烯醇硅醚、吲哚等多种亲核试剂与DA环丙烷的高对映选择性开环/环化反应。 本文结合我们课题组工作综述了DA环丙烷化合物的不对称合成、开环/环化反应以及动力学拆分方面的主要研究进展并进行了展望。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.