Lipase-catalyzed Knoevenagel condensation between α,β-unsaturated aldehydes and active methylene compounds

A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL(lipase from porcine pancreas) with satisfied yields(49%–92%).Moreover,PPL induces moderate Z/E selectivity in the Knoevenagel condensation.     

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety ofα,β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl_3 in aqueous media to afford the corresponding products in good to excellent yields.     

Stereoselective cycloaddition of N-acyliminium cations withα,β-unsaturated ketones and esters

The cycloaddition of N-acyliminium cations with some deactivated alkenes such asα,β-unsaturate ketones and esters has been investigated.In most cases,the N-acyliminium cations produced from 3-hydroxy-2-arylisoindol-1-ones in the presence of BF_3·OEt_2 could be reacted withα,β-unsaturated ketones and esters to afford stereoselectively the cycloaddition products 6-acylisoindolo[2,1-a] quinolin-11-ones in moderate to high yields.     

A Novel Approach to Synthesis of α，β－Unsaturated Ketones

A new approach to the synthesis of α，β-unsaturated ketones from 1,2,3-trimethyl benzimidazolium salt via the condensation reaction with aldehydes followed by the addition reaction of Grignard reagents with quaternary C=N bond was provided.     

Asymmetric Michael addition of silyl nitronates to cyclic α,β-unsaturated ketones catalyzed by chiral quaternary ammonium bifluorides: isolation and selective functionalization of enol silyl ethers of optically active γ-nitro ketones

Highly enantioselective Michael addition of silyl nitronates to cyclic α,β-unsaturated ketones has been accomplished by the utilization of N-spiro C₂-symmetric chiral quaternary ammonium bifluoride 1 as an efficient catalyst, offering a new route to the enol silyl ethers of optically active γ-nitro ketones. The synthetic utility of this transformation has been demonstrated by the diastereoselective derivatizations of the optically active enol silyl ethers to the corresponding α-substituted cyclic ketones having three consecutive stereochemically defined stereocenters.     

Highly diastereoselective and enantioselective Michael addition of 5H-oxazol-4-ones to α,β-unsaturated ketones catalyzed by a new bifunctional organocatalyst with broad substrate scope and applicability

A new thiourea-tertiary amine bifunctional catalyst derived from L-tert-leucine was developed and provides excellent stereocontrol in a novel and direct Michael addition of 5H-oxazol-4-ones to α,β-unsaturated ketones with much broad substrate scope. The conjugate addition products with chiral vicinal quaternary and tertiary stereocenters can be easily transformed to structurally interesting compounds or building blocks.     

Rongalite and base-promoted cleavage of disulfides and subsequent Michael addition to α,β-unsaturated ketones/esters: an odorless synthesis of β-sulfido carbonyl compounds

A highly practical method to access β-sulfido carbonyl compounds was developed, which could be conducted without any expensive reagent, special apparatus/technique, and no requirement of metal catalysts. β-Sulfido carbonyl compounds were formed at room temperature, in short time and with high chemoselectivity in good to excellent yields. A plausible mechanism for the role of Rongalite^®, as a promoter for the cleavage of disulfides generating thiolate anions that then undergo facile thia-Michael addition to α,β-unsaturated ketones and esters is proposed.     

Divergent pathways of β,γ-unsaturated α-diazocarbonyl compounds catalyzed by dirhodium and Lewis acids catalysts separately or in combination

β,γ-Unsaturated a-diazocarbonyl compounds possess two reactive sites for electrophilic addition-one at the diazo carbon and the other at the vinylogous γ-position.Controlled by catalyst,divergent transformations are achieved starting from the same starting materials,either by Lewis acid-catalyzed addition or by dirhodium-catalyzed metal carbene reactions.In select cases two catalysts working in combination or in sequence provide a relay for cascade transformations.In this review,we summarize advances in catalyst-dependent divergent transformations of β,γ-unsaturated α-diazocarbonyl compounds and highlight the potential of this exciting research area and the many challenges that remain.     

Phosphinite- and phosphite-based Type I palladacycles as highly active catalysts for addition reactions of arylboronic acids with aldehydes, α,β-unsaturated ketones, α-ketoesters, and aldimines

Phosphinite- and phosphite-based type I palladacycle-catalyzed additions of arylboronic acids with aldehydes, α,β-unsaturated ketones, α-ketoesters, and aldimines are described. Our study showed that readily available phosphinite- and phosphite-based type I palladacycles could possess higher catalytic activity than phosphine-based palladacycles and were highly active, practical catalysts. Our study may pave the road for development of optically active phosphinite- and phosphite-based palladacycles for asymmetric catalysis.     

钯催化卤代芳烃直接对α,β不饱和酮的1,4-加成反应研究

研究了钯催化卤代芳烃直接对α,β-不饱和酮化合物的1,4-加成反应.发现在Pd(PPh3)4催化剂的存在下,反应在N,N-二甲基乙酰胺溶剂中,加热至80℃,可以顺利进行,得到β-芳基酮化合物.该方法避免使用价格昂贵的氮杂环卡宾配体和有机金属试剂,具有操作简单、选择性好等优点。     

Michael-Addition Reaction of Malononitrile with α,β-Unsaturated Cycloketones Catalyzed by KF／Al2O3

A series of KF/Al2O3 catalyzed Michael-addition reactions between malononitrile and α,β-unsaturated cycloketones in DMF solution were studied. At room temperature, 2-cyano-3-aryl-3-(1,2,3,4-tetrahydronaphthalen-1-one-2-yl) propionitrile derivatives were synthesized by the reaction between 2-arylmethylidene-1,2,3,4-tetra-hydronaphthalen-1-one and malononitrile. However, if the temperature was increased to 80℃, 2-amino-3-cyano-4-aryl-4H-benzo[h]chromene derivatives were obtained in high yields. When the α,β-unsaturated ketones were replaced by 2,6-biarylmethylidenecyclohexanone or 2,5-biarylmethylidenecyclopentanone, another series of 2-amino-3-cyano-4H-pyran derivatives was isolated successfully. The structures of the products were confirmed by X-ray diffraction analysis.     

α-羰基烯酮环二硫代缩醛化学(XXXVI)──β,β-1,3-亚丙二流基-α,β-不饱和芳酮与Grignard试剂加成物的硅胶催化分解反应

以β，β-1，3-亚丙二硫基-α，β-不饱和芳酮2与烯丙基或等基Grfenard试剂可选择性地进行1，2-加成得醇3、4，在硅胶G的催化下，醇3、4可分解生成β，γ-不饱和芳酮5、6．并对该分解反应的机制进行了初步探讨．     

A Facile and Efficient Oxidation of α,β-Unsaturated Alcohols with Manganese Dioxide in Ionic Liquids under Mild Conditions

The oxidation of α,β-unsaturated primary and secondary alcohols to corresponding aldehydes and ketones by manganese dioxide in ionic liquids as a safe recyclable and accelerative reaction medium under mild conditions are described. The rate of the oxidation reaction is faster and the yield is higher than that with conventional procedures.     

α-羰基烯酮环二硫代缩醛化学(Ⅵ)——β,β-1,3-亚丙二硫基-α,β-不饱和芳酮与烯丙基Grignard试剂加成物脱水反应的研究

提出了由β,β-1,3-亚丙二硫基-α,β-不饱和芳酮类化合物(1)与苄基氯化镁及烯丙基溴化镁加成所得的醇(2)在BF_3·Et_2O催化下脱水生成共轭烯烃(3)新的合成途径,合成了13种新化合物,结构经~1H N-MR、IR、UV及元素分析等确证.并对这一新合成途径的反应机制进行了讨论.     

简便高效合成15β,16β-亚甲基-雄甾-5-烯-3β-醇-17-酮

采用对甲苯磺酸(pTsOH)和i氟乙酸(TFA)为催化剂,邻碘酰苯甲酸(IBX)为氧化剂,于40-45℃,在T01.DMSO混合溶剂中,将醋酸去氢表雄酮选择性脱氢,简便高效地制备了3β-乙酰氧基.雄甾-5.15-二烯-17-酮(I),产率分别为77%和89%.本合成线路有效避免了经溴代脱溴和发酵等合成线路反应繁多、试剂毒性大、成本高以及单纯IBX选择性脱氢反应温度高、反应时间长等不足.然后将化合物I在碱性条件下水解得到3β-羟基.雄甾-5,15-二烯-17-酮(Ⅱ),产率92%.最后将化合物Ⅱ与碘化三甲基氧化锍进行迈克尔共轭加成制得目的物15β,16β-亚甲基.雄甾-5-烯-3β-醇-17-酮(Ⅲ),产率89%.中间体和目的物经紫外光谱、红外光谱、核磁共振氧谱、质谱及元素分析确证了其化学结构.     

Spectrophotometric Study of Reaction Between Platinum and α,β,γ,δ-Tetra-(2-Chlorophenyl) Porphyrin

The present paper describes the complex reaction of α, β,γ, δ-tetra-(2-chlorophenyl} porphyrin with platinum in the presence of the mixture surfactant, sodium dodecylbenzene sulfonate and OP, and a new highly sensitive method for spectrophotometric determination of micro amounts of platinum. Beer's Law was obeyed when the concentration of platinum was in the range of 0?.2μg/25ml. The molar absorptivity was found to be 3.1×106 L mol-1 cm-1 at 417nm.     

Catalytic conjugate addition of indole toα,β-unsaturated ketones by Co（ClO4）-2·6H2O/bis-Schiff base complexes

Co（ClO₄）)₂·6H₂O/bis-Schiff base complexes promoted the conjugate addition of indole toα,β-unsaturated ketones under mild conditions,giving the corresponding addition products with high yields.And the complex has been characterized with XRD and IR.     

手性方酰胺催化环状1,3-二羰基化合物对β,γ-不饱和-α-酮酯的不对称Michael加成反应（英文）

发展了新型手性双功能叔胺-方酰胺催化的环状1,3-二羰基化合物和β,γ-不饱和-α-酮酯之间的不对称Michael加成反应,反应条件温和,底物适用范围广泛,相应产物的产率和对映选择性分别高达97%和97%ee,为合成和医药上极为重要的手性色烯衍生物的立体选择性合成提供了一种实用的方法.     

Keggin类杂多化合物催化α,β-不饱和羰基化合物环氧化

在乙睛溶剂中考察了一系列杂多化合物和过氧化氢水溶液催化的各种缺电子的α,β-不饱和羰基化合物的环氧化反应.在所研究的杂多化合物中,二缺位的[γ-SiW10(H2O)2O34](Bu4N)4显示出了最高的活性.