A convenient synthesis of olefins via deacylation reaction

A convenient and environmentally-friendly synthetic method of olefins via deacylation reaction is described. The reaction gives olefins by condensation of aldehydes with a variety of 1,3-dicarbonyl compounds in the presence of anhydrous potassium carbonate at room temperature in high yields (70-90%) in one step. The synthetic potential of this strategy can be used as an alternative procedure to the Wittig, Wittig-Horner reactions. The stereochemistry of the resulted olefins was determined by NOE experiment with correct radio frequency and X-ray analysis. The E/Z selectivity of the deacylation reaction depends on the α-substituents of the 1,3-dicarbonyl compounds.     

Direct synthesis of oxazolines from olefins and amides using t-BuOI

A new and simple method for the synthesis of oxazolines from readily accessible olefins and amides using tert-butyl hypoiodite is described; aromatic/aliphatic olefins and amides can be used in the reaction to give a variety of oxazolines.     

Copper-Catalyzed Borylative Couplings with C−N Electrophiles

Copper-catalyzed borylative multicomponent reactions (MCRs) involving olefins and C−N electrophiles are a powerful tool to rapidly build up molecular complexity. The products from these reactions contain multiple functionalities, such as amino, cyano and boronate groups, that are ubiquitous in medicinal and process chemistry programs. Copper-catalyzed MCRs are particularly attractive because they use a relatively abundant and non-toxic catalyst to selectively deliver high-value products from simple feedstocks such as olefins. In this Minireview, we explore this rapidly emerging field and survey the borylative union of allenes, dienes, styrenes and other olefins, with imines, nitriles and related C−N electrophiles.     

A Strategy toward Cyclic Topologies Based on the Dynamic Behavior of a Bis(hindered amino)disulfide Linker

A simple and efficient method to generate macrocyclic structures has been developed based on the dynamic behavior of the linker bis(2,2,6,6‐tetramethylpiperidin‐1‐yl)disulfide (BiTEMPS). The prime linear structure was transformed into a (macro)cycle using the following sequence: 1) thiol–ene reaction with a BiTEMPS derivative to afford the linear precursor, then 2) an entropy‐driven transformation induced by diluting and heating. The radicals generated from BiTEMPS upon heating are highly tolerant toward a variety of chemical species, including oxygen and olefins, but they exhibit high reactivity in exchange reactions, which can be applied to the topology transformation of various skeletons. The advantages of the present method, namely, its procedural simplicity and substrate versatility, are demonstrated by the gram‐scale synthesis of cyclic compounds with low and relatively high molecular weight.     

Metallophthalocyanine catalyzed olefination of aldehydes

The Wittig reaction to synthesize olefins is a very attractive method in organic synthesis. Recently, this methodology has been achieved utilizing simple metal catalysts and diazo compounds in addition to a phosphine and an aldehyde. The following work investigates the use of a variety of metallophthalocyanines (MPc’s) to catalyze Wittig-like reactions from ethyldiazoacetate. We also examine the influence of substitution on the aromatic ring of the aldehyde as well as various phosphines, arsines and antimony complexes. We have been able to exclusively synthesize the trans-olefins in excellent yields in short periods of time (1?h).     

Rhodium fluorapatite catalyst for the synthesis of trisubstituted olefins via cross coupling of Baylis-Hillman adducts and arylboronic acids

Treatment of fluorapatite (prepared by incorporating basic species F(-) in apatite in situ by coprecipitation) with an aqueous solution of RhCl(3) resulted in rhodium-exchanged fluorapatite catalyst (RhFAP), which successfully promoted cross coupling of Baylis-Hillman adducts with arylboronic acids to yield trisubstituted olefins. A variety of arylboronic acids and Baylis-Hillman adducts were converted to the corresponding trisubstituted olefins, demonstrating the versatility of the reaction. The reaction is highly stereoselective. RhFAP was recovered quantitatively by simple filtration and reused with almost consistent activity.     

Synthesis of cyclobutylideneacetic esters via aluminum chloride promoted [2+2] cycloadditions of ethyl 2,3-butadienoate to olefins

In the presence of AlCl₃, ethyl 2,3-butadiemoate reacts with a variety of olefins, including simple unactivated cycloalkenes, to give cyclobutylideneacetic esters at room temperature. The cycloaddition is regioselective and stereoselective.     

合成气催化转化直接制备低碳烯烃研究进展

合成气直接催化转化制备低碳烯烃是C1化学与化工领域中一个极具挑战性的研究课题,具有流程短、能耗低等优势,已成为非石油路径生产烯烃的新途径。直接转化方式主要包括经由OX-ZEO双功能催化剂直接制低碳烯烃的双功能催化路线以及经由费托反应直接制备低碳烯烃的FTO路线。综述简述了近年来在合成气直接制备低碳烯烃方面的研究进展,重点讨论了低碳烯烃的形成机理、新型催化剂的研发及助剂对其催化性能的影响,并对合成气直接制烯烃的未来进行了展望。     

[2+2]环加成反应机理的理论研究

[2+2]环加成反应是有机化学中非常重要的一类反应,其机理的研究一直是实验和理论工作者关注的课题之一。本文从理论的角度综述了三类[2+2]环加成反应的反应机理,即简单烯烃或炔烃参与的环加成反应、累积双键体系参与的环加成反应以及稀土钍化合物参与的环加成反应, 得出对于简单的烯烃或炔烃之间的环加成反应一般是按双自由基机理进行,而其他两类反应主要按协同或两性离子方式进行,并且从前线分子轨道作用理论角度分析了产生不同反应机理的原因。     

Direct organocatalytic hydroalkoxylation of α,β-unsaturated ketones

The direct addition of a variety of alcohols to in situ activated olefins was observed in the presence of mild bifunctional amine/acid catalysts. Unlike existing methods, the reactions proceed at room temperature and in the absence of transition metals. The use of simple commercially available catalysts, amines and acids makes this an attractive method for the preparation of β-alkoxy ketones, which are prevalent targets and intermediates in organic synthesis.     

Iodine as a mild and versatile reagent for the synthesis of 1,3-dioxane derivatives via the Prins reaction

Iodine is found to be an effective reagent for the cross-coupling of olefins with aldehydes under mild conditions to produce 4-substituted 1,3-dioxane derivatives in excellent yields and in short reaction times with high selectivity. The use of iodine makes this procedure simple, convenient, cost-effective and practical. This method works not only with formaldehyde but also with acetaldehyde, propionaldehyde and cyclohexanecarboxaldehyde.     

Synthesis of symmetrical trisubstituted olefins by cross metathesis

[reaction: see text] Trisubstituted alkenes have been prepared via intermolecular olefin cross-metathesis (CM) between alpha-olefins and symmetrically 1,1-disubstituted olefins using an imidazolylidene ruthenium benzylidene complex. Of particular interest is the synthesis of isoprenoid/prenyl groups by a simple solvent-free CM reaction with isobutylene. In addition, prenyl groups can also be installed by a cross-metathesis of 2-methyl-2-butene with a variety of alpha-olefins at room temperature with low catalyst loadings.     

Silica Gel,an Effective Catalyst for the Reaction of Electron-Deficient Nitro-Olefins with Nitrogen Heterocycles

The reaction of electron-deficient olefins with nitrogen heterocycles such as pyrrole and indole was examined in the presence of silica gel at room temperature under stirring at solvent-free conditions. It was found that silica gel is an effective catalyst for this conjugate addition. This work resulted in the formation of monosubstituted pyrroles selectively as a major product except in a few cases where disubstituted pyrroles were also formed as side products. Thus, a simple, rapid, efficient, environmentally benign, and solvent-free method was established.     

Immobilization and Continuous Recycling of Photoredox Catalysts in Ionic Liquids for Applications in Batch Reactions and Flow Systems: Catalytic Alkene Isomerization by Using Visible Light

A catalytic (E)‐ to (Z)‐isomerization of olefins using a photoredox catalyst under mild reaction conditions is presented. A variety of (Z)‐alkenes can be prepared in the presence of visible light. A new reaction system allows an easy and efficient scale‐up, as well as a continuous flow process in which the photocatalyst is immobilized in an ionic liquid and continuously recycled by simple phase separation.     

TEMPO oxoammonium salt-mediated dehydrogenative Povarov/oxidation tandem reaction of N-alkyl anilines

The synthesis of a variety of substituted quinolines from N-alkyl anilines by a one-pot dehydrogenative Povarov/oxidation tandem reaction with mono- and 1,2-disubstituted aryl and alkyl olefins was developed. A simple protocol using cheap and benign iron(III)chloride as the Lewis acid catalyst and a TEMPO oxoammonium salt as a nontoxic, mild, efficient oxidant is reported.     

Alder-ene reaction of aryne with olefins

A novel intermolecular Alder-ene reaction based on aryne and olefins was developed. We performed this transformation under mild conditions such as at room temperature, and this reaction displayed high selectivity and good yields only in the presence of CsF. Hence, the intermolecular Alder-ene reaction of aryne with olefins provides an effective route to synthesize derivatives of olefins.     

Synthesis of Spirocycles via Ni-Catalyzed Intramolecular Coupling of Thioesters and Olefins

A nickel-catalyzed intramolecular coupling of thioesters and olefins has been developed for the efficient synthesis of spirocycles, a privileged scaffold commonly found in natural products. This transformation is characterized by the simultaneous transfer of both acyl and thiol moieties to the alkene, with the suppression of decarbonylation and β-hydrogen elimination. Initial mechanistic investigations are consistent with an oxidative addition/olefin insertion/reductive elimination mechanism. The incorporated methylene sulfide substituent can undergo a variety of further reactions to increase molecular diversity and complexity. These results demonstrate that thioester derivatives can be used as powerful building blocks for the assembly of complex scaffolds.     

Facile one-pot synthesis of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent

A new method for the preparation of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent has been developed. Several α-bromoketones were successfully prepared from a variety of olefins by this method. This procedure is an alternative to conventional molecular bromine.     

Carbon nanotubes-supported palladium nanoparticles for the Suzuki reaction in supercritical carbon dioxide: A facile method for the synthesis of tetrasubstituted olefins

A facile and efficient method for the synthesis of tetrasubstituted olefins in supercritical carbon dioxide was developed by using carbon nanotubes-supported palladium nanoparticles (Pd/CNTs) as the catalyst. Compared with common Pd/C, Pd/CNTs could more effectively catalyze the reaction of dibromo-substituted olefins with boronic acids, affording the corresponding tetrasubstituted olefins with moderate to good yields. This environmentally benign route with an easy-to-handle catalyst provides an appealing alternative to the currently available methods.     

4-氨基吡啶树脂负载钯(Ⅱ)催化Heck反应研究

将4-氨基吡啶树脂负载钯配合物（简写为4-APR-Pd(Ⅱ)）用于卤代或杂环卤代芳烃与烯烃的Heck反应可以获得满意的收率,该法具有环境友好、实用性及树脂催化剂的重复使用性能等特点。并对反应条件进行了讨论,所得产物用1H NMR、13C NMR、红外光谱及元素分析进行了表征。