氮杂环丙烷[3+2]环加成反应研究进展

介绍了最近几年在不同催化体系下,氮杂环丙烷与含双键化合物的[3+2]环加成反应研究进展。     

脒参与的环加成反应的研究进展

环加成是两个或多个分子通过结合生成环状化合物的反应,在有机合成中起着非常重要的作用。脒是一类重要的有机含氮化合物,作为有机合成中间体,它可与含有各种不饱和键的化合物发生不同类型的环加成反应来制备多种含氮杂环化合物;这些杂环化合物骨架广泛存在于医药、农药、材料和天然产物等分子结构中。对近几年脒与含有各种不饱和键化合物发生的各种环加成反应进行了综述,主要包括[3+3]、[3+2]、[3+5]、[4+2]和[2+3]等环加成反应,并对其发展方向进行了展望。     

腙参与的环加成反应研究进展

环加成是两个或多个分子通过结合生成环状化合物的反应,它在有机合成中起着非常重要的作用。腙是一类重要的有机含氮化合物,作为有机合成中间体,它可与含有各种不饱和键的化合物发生不同类型的环加成反应来制备多种含氮杂环化合物;这些杂环化合物骨架广泛存在于医药、农药、材料和天然产物等分子结构中。主要对近几年腙与含有各种不饱和键化合物发生的各种环加成反应进行了综述,主要包括[3+3]、[3+2]、[3+4]、[4+2]和[4+3]等环加成反应,并对其发展方向进行了展望。     

氮杂环丙烷与腈的[3+2]环加成反应生成咪唑啉的研究进展

咪唑啉是一种非常重要的药物中间体,其通过氮杂环丙烷与腈的[3+2]环加成反应是非常有效合成方法.综述了这种方法的研究进展,并且进行了评价与展望.     

环丙烷环加成反应的研究进展

环加成反应是有机合成化学中非常重要的一类反应,是两个或多个分子通过结合生成多元环状化合物的有效方法。环丙烷由于其特殊的三元环状结构及反应活性,可与许多不饱和化合物发生环加成反应来制备多种多元环状化合物。综述了近十年内环丙烷与一些化合物发生的环加成反应,主要包括[3+2]和[3+3]环加成反应,并对其发展方向进行了展望。     

功能化分子筛催化氮杂环丙烷与异硫氰酸酯[3+2]环加成反应的研究

主要研究了固体酸催化剂对氮杂环丙烷与异硫氰酸酯间的[3+2]环加成反应的催化效果,并对反应展开了一系列底物拓展。实验结果表明,在该催化体系下,反应都有不错的收率。并且通过催化剂重复性实验,也可以发现,经过多次重复利用的固体酸也可以起到有效的催化作用。     

氮杂环丙烷与CO_2反应的最新研究进展

二氧化碳既是温室气体的主要成分,也是储量丰富的碳资源,研究二氧化碳的转化与利用有着重要的意义。总结了近几年各种催化体系催化氮杂环丙烷与CO_2的环加成反应,包括不可回收催化剂、可回收催化剂和无催化剂体系,以及各体系对氮杂环丙烷与CO_2环加成反应产物收率和区域选择性的影响。     

二烯酮类化合物在构建复杂有机化合物中的应用

二烯酮作为一类具有多个化学反应位点的不饱和酮类化合物,可与多种反应底物实现不同类型的化学转化,高效快捷地构建功能各异的有机化合物。该文综述了近些年二烯酮类化合物与多种反应底物的化学转化。首先,探讨了2,5-环己烯酮类化合物与不同试剂的串联Michael-Smiles环丙烷化反应、环加成反应、三组分Ritter反应、光化学重排反应和氧化偶联反应分别构建了环丙烷类衍生物、氮杂螺环类衍生物、含氟烷基N,O-缩酮类衍生物、稠环吲哚类化合物、酰胺类化合物和不对称联芳烃类化合物。接着,分析了1,4-戊二烯-3-酮类化合物与丙二腈(硝基甲烷)、硫氢化钠、氧化吲哚、吡唑酮、芴和巴比妥酸双Michael加成反应,分别合成了多取代环己酮类化合物、二芳基噻喃酮类化合物、螺环氧化吲哚类化合物、螺环吡唑酮类化合物、螺环芴类化合物和螺环巴比妥类衍生物。然后,介绍了2,4-戊二烯-1-酮类化合物的1,4-共轭加成、氮杂Michael加成反应、分子内Morita-Baylis-Hillman (MBH)反应、分子内还原Aldol反应、分子内Aldol反应和分子内[4+2]环加成/氧化反应分别实现了有机含硫化合物、有机含氮化合物、多取代茚酮类化合物和SGLT2抑制剂——托格列净关键中间体的制备。最后,对二烯酮在后续化学反应中的潜在应用进行了展望。     

联烯类化合物[3+2]环加成反应的研究进展

环加成反应是有机化学中非常重要的一类反应,常用于多元环类化合物的合成。联烯是具有丙二烯结构单元的一类不饱和化合物,广泛存在于自然界中,由于其特殊结构与反应活性,可与许多含不饱和键的化合物发生环加成反应来制备吲哚、呋喃或吡啶等多种环状化合物。近年来,联烯及其衍生物已经引起了国内外许多科研工作者的兴趣。综述了近几年联烯类化合物与含各种不饱和键化合物[3+2]环加成反应的研究进展,并对其发展方向进行了展望。     

铑催化的重氮化合物与吲哚的环加成反应

由于重氮化合物金属卡宾具有独特的反应特性,所以成为了有机化学领域的研究热点。在金属铑的催化作用下,重氮化合物能够形成铑金属卡宾,此金属卡宾具有吲哚与此金属卡宾发生[2+1]环加成反应。文章简单介绍了重氮化合物与3-乙烯基吲哚的环加成反应。     

Pericyclic Organometallic Reactions. Substituent Effects on Cycloadditions and Rearrangements of (η4-cycloheptatriene)Fe(CO)3 Derivatives

The mechanism of the reactions of (η⁴-cycloheptatrien-1-al)Fe(CO)₃ and its ethyleneglycol acetal with tetracyanoethylene (TCNE) was studied. The aldehyde undergoes a fast reversible 3+2 cycloaddition involving the free aldehyde-substituted double bond, and a slow irreversible 3+2 cycloaddition at the coordinated site. The latter, σ,π-allylic complex undergoes a slow interconversion with the corresponding 5 +2 isomer via the pericyclic [3,3]-sigmahaptotropic rearrangement. In contrast, the acetal reacts with TCNE at the free acetal-substituted double bond to give a single kinetic 3+2 adduct, which, under thermodynamic conditions, undergoes a [4,4]-sigmahaptotropic rearrangement to the 6 + 2 adduct. The reaction kinetics was followed by ¹H NMR. The effect of substituents on the reaction course is discussed, and the detailed mechanism of both the cycloadditions and rearrangements is described.     

Photochemie von Acylaziden. VIII [1]. Reagieren Acylnitrene wie 1,3-Dipole??

Photochemistry of Acylazides. VIII. Do Acylnitrenes React like 1,3-Dipoles? The formation of three- ore five-membered heterocyclic rings by the reaction of acylnitrenes with olefins depends on the electron density at the double bond. The generally expected formation of aziridines by a cheletropic reaction was observed by photolysis of aroylazides 1 in the presence of 2,5-dihydrofuran 2 . But with enolethers 3 and 4 oxazolines were directly formed. This [3 + 2] cycloaddition is regiospecific. The cycloaddition is modestly stereoselective by steric hindrance within the cyclic enolether 3b . Very small de-values were found with chiral substituents in the acylazide 13 . The azide decomposition was also achieved by photoinduced electron transfer. The same cycloaddition products as obtained by direct photolysis of the azides were obtained via radical anions of the acylazide. Using Michler's ketone as electron donor in the triplet state the formation of isocyanate which diminishes the yield of cycloadducts can be avoided.     

Azo Bridges from Azine 9. [2 + 2 + 1] Cycloadditions of Parallel C=C and N=N Bonds with Dihalocarbenes

Schemes 1 and 2 are examples of type A compounds in which the groups -N=N- and -CH=CH- are held in a close parallel position. They react with dichloro- and fluorochlorocarbene to form a unique pyrazolidine moiety (3–5) in a formal [2 + 2 + 1] cycloaddition which, despite the substitution pattern, is stable to ionization and hydrolysis according to Bredt's rule. The reaction is considered to start with the addition of the carbenes to the azo group. The azomethine imine thus formed subsequently undergoes a rapid [3 + 2] dipolar cycloaddition with the bridging C=C bond. The different isomers from 3–5 are identified from their NMR spectra.     

Organometallic-like C-H bond activation and C-S bond formation on the disulfide bridge in the RuSSRu core complexes

C-S bond formations on the disulfide bridge in the dinuclear Ru(III) complexes have been found in the reaction with unsaturated organic molecules, such as alkenes and ketones. The reactions are initiated by the organometallic-like C-H bond activation. Through the mechanistic study of these novel reactions, the specific nature of the disulfide bridging ligand has been unveiled: (i) the double bond character of the sulfur-sulfur bond, which allows the Diels-Alder-type [4 + 2] cycloaddition reaction with butadiene to form a C(4)S(2) ring, (ii) the C-H bond activation on the S-S bond forming a C-S bond. All of the C-H activation reactions and the ensuing C-S bond formation reactions suggest that the disulfide ligand can act in a manner similar to the transition metal centers of the organometallic complexes.     

A Facile and Efficient Synthesis of Dihydroisobenzofuran Derivatives via Tandem Palladium‐Catalyzed Coupling,Propargyl‐Allenyl Rearrangement, [4+2] Cycloaddition and Aromatization Reaction

A variety of dihydroisobenzofuran derivatives has been prepared in good yields via an interesting sequential reaction consisting of palladium‐catalyzed coupling, propargyl‐allenyl rearrangement, [4+2] cycloaddition and aromatization. A double‐coupling, rearrangement, [4+2] cycloaddition and aromatization process is also described for the synthesis of more complex and diverse structures.     

Interrogation of an Enzyme Library Reveals the Catalytic Plasticity of Naturally Evolved [4+2] Cyclases

Stereoselective carbon-carbon bond forming reactions are quintessential transformations in organic synthesis. One example is the Diels-Alder reaction, a [4+2] cycloaddition between a conjugated diene and a dienophile to form cyclohexenes. The development of biocatalysts for this reaction is paramount for unlocking sustainable routes to a plethora of important molecules. To obtain a comprehensive understanding of naturally evolved [4+2] cyclases, and to identify hitherto uncharacterised biocatalysts for this reaction, we constructed a library comprising forty-five enzymes with reported or predicted [4+2] cycloaddition activity. Thirty-one library members were successfully produced in recombinant form. In vitro assays employing a synthetic substrate incorporating a diene and a dienophile revealed broad-ranging cycloaddition activity amongst these polypeptides. The hypothetical protein Cyc15 was found to catalyse an intramolecular cycloaddition to generate a novel spirotetronate. The crystal structure of this enzyme, along with docking studies, establishes the basis for stereoselectivity in Cyc15, as compared to other spirotetronate cyclases.     

Cytotoxic Activity of Silyl- and Germyl-Substituted 4,4-Dioxo-3a,6a-Dihydrothieno[2,3-d]isoxazolines-2

The [2+3] dipolar cycloaddition of nitrile oxides to the double C = C bonds of thiophene-1, 1-dioxides leads to formation of the fused isoxazolines-2 (1, 2). Tumor growth inhibition of these compounds strongly depends on the nature of group IV A element increasing from slightly active tert-butyl derivatives to silicon and germanium containing analogues. The products of benzonitrile oxide cycloaddition have greater cytotoxic effect than the compounds obtained from the cycloaddition reaction of 2, 5-disubstituted thiophene-1, 1-dioxides with acetonitrile oxide. Fused silyl substituted isoxazolines-2 are stronger NO-inducers than their germyl and tert-butyl analogues.     

[Ni(phen)_3]_2(1,2,4,5-H_3BTC)_2(1,2,4,5-H_2BTC)·2H_2O的水热合成和晶体结构

近年来配位聚合物因其结构多样性及在催化、药物载体和气体吸附脱附等方面具有潜在的应用价值[1-3]而得到迅速的发展。本文在水热条件下,成功的合成出一例新型的一维超分子化合物,[Ni(phen)3]2(1,2,4,5-H3BTC)2(1,2,4,5-H2BTC)·2H2O。X-射线单晶衍射分析表明,化合物属于三斜晶系,P1空间群,晶胞参数为a=1.2403(3)nm,b=1.2907(3)nm,c=1.4512(3)nm,α=96.261(5)°,β=106.500(6)°,γ=105.061(4)°,V=2.1086(8)nm3,Z=2。在该化合物中,[Ni(phen)3]2+阳离子与[H3BTC]-和[H2BTC]2-阴离子通过静电引力、分子间氢键和分子内氢键,形成一个一维超分子链状结构。     

Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones

Cinnamate polymers are well known photoreactive polymers due to [2+2] cycloaddition reaction of cinnamate side group. In this work, we have found that the cinnamate side groups could be also reacted by thermal energy, and this reaction is presumed to attribute to the radical reaction of carbon double bond in the cinnamate groups. Contrary to the photocycloaddition reaction of the cinnamate side groups, the thermal reaction of cinnamate side group was closely related to the flexibility of polymer backbone. The difference of the mechanism between the photocycloaddition reaction and thermal crosslinking reaction was confirmed by ¹H NMR and ¹³C NMR analysis of the model compound.     

扁柏醇合成工艺研究

以普通化工原料CPD(环戊二烯)和NaH为原料,经Wurtz取代反应、【2+2】环加成反应和Beckmann重排反应三步骤合成高纯度扁柏醇,反应条件温和,原料廉价易得,经检测纯度可稳定达到99.8%左右。该方法优于其它反应步骤较多、合成条件苛刻的全合成工艺和传统提取工艺,可实现工业大规模生产。