吗啉催化的串联反应合成多取代环己酮（英文）

本文以吗啉为催化剂,活泼亚甲基化合物与芳香醛发生串联反应,以最高90%的产率得到了系列多取代的环己酮。反应经历了Knoevenagel缩合、Michael加成、Aldol反应等系列过程。吗啉作为有机分子催化剂,在串联过程中通过亚胺离子活化及烯胺活化羰基化合物而发挥重要作用。合成的环己酮可通过已知方法进一步转化为2-环己烯酮。本方法具有简便、易操作和绿色的特点。     

吗啉催化的串联反应合成多取代环己酮

摘 要本文以吗啉为催化剂,活泼亚甲基化合物与芳香醛发生串联反应,以最高90%的产率得到了系列多取代的环己酮。反应经历了Knoevenagel缩合、Michael加成、Aldol反应等系列过程。吗啉作为有机分子催化剂,在串联过程中通过亚胺离子活化及烯胺活化羰基化合物而发挥重要作用。合成的环己酮可通过已知方法进一步转化为2-环己烯酮。本方法具有简便、易操作和绿色的特点。     

铜催化C—H活化/C—S偶联反应合成环烷基芳基硫醚

为设计一种利用廉价催化剂以达成C—H活化构建C—S的方法,本文研究了铜催化C—H活化/C—S偶联反应合成系列环烷基芳基硫醚化合物。以芳基磺酰肼与环烷烃为原料,溴化亚铜为催化剂,二叔丁基过氧化物(DTBP)为氧化剂,120℃反应24 h,经氧化脱氮C—H活化/C—S偶联串联反应过程,合成了系列环烷基芳基硫醚化合物。该反应适合环戊烷、环己烷、环庚烷、环辛烷和环十二烷等环烷烃和不同取代基团(甲氧基、硝基、氯和甲基)的芳基酰肼,合成得到了18个芳基硫醚类化合物,产率为41%～72%。其结构经¹H NMR、¹³C NMR和HR-MS进行了表征。     

N-(1-环己烯基)吗啉制备实验的改进

实验教材上以吗啉和环己酮为原料,对甲基苯磺酸为催化剂,甲苯作带水剂,通过缩合反应制备N-(1-环己烯基)吗啉。实验存在着耗时长、易造成实验室内有毒气体甲苯含量高、产品色泽深和收率低(小于60%)等不足。依据实验的目的、原理、内容不变的原则,采用 n/n为1.6,预缩合反应1 h后加入共沸剂,反应加入对苯二酚,环己烷作共沸剂,分馏提纯产品等措施进行改进实验。改进后的实验,反应时间缩短了1 h、室内空气环境友好、产品近乎无色、收率可达80%以上。环己酮吗啉     

十聚钨酸盐催化环己醇制备环己酮工艺研究

合成新型N-甲基吗啉十聚钨酸盐[Mor1,2]4W10O32,对其进行提纯、表征和催化性能研究。催化体系是以[Mor1,2]4W10O32为催化剂,30%H2O2为氧化剂,催化氧化环己醇制备环己酮。考察催化剂用量、氧化剂用量、反应温度变化和反应时间变化对环己酮产率的影响,确定最佳反应条件为:反应温度80℃、环己醇用量5mmol、催化剂用量30μmol、氧化剂H2O2用量12.5 mmol,反应时间6小时,此时环己酮产率可达到96%。     

氢键活化的硝基烯参与的多组分不对称串联合成研究进展

有机催化多组分不对称串联反应是构建复杂手性化合物的最有效方法之一,双功能手性催化剂是一类重要的单分子双活化有机小分子催化剂,能同时对多个反应底物进行氢键活化,实现多个新键的形成和多个手性中心的立体选择性控制.基于双功能催化剂氢键活化的硝基烯是一类重要的有机反应合成子,能参与多种有机小分子催化的串联反应.对硝基烯参与的多组分不对称串联反应,根据双功能催化剂的结构特征,从双功能硫脲-胺催化、双功能方酰胺-胺催化、其它双功能催化剂催化三个方面进行文献综述.从反应类型、反应机理、反应特点及应用等方面进行了系统地阐述,并对该领域的研究应用和发展前景进行了展望.     

5,6,7,8-四氢苯并[4,5]噻吩并[2,3-d]嘧啶-4(3H)-酮类查尔酮的设计、合成及体外抗肿瘤活性

以环己酮、氰乙酸乙酯、硫粉和吗啉为原料,依次通过Gewald反应、关环反应、Chan-Lam偶联反应和Claisen-Schmidt缩合反应以23.9%-40.9%的总收率合成了18个新型5,6,7,8-四氢苯并[4,5]噻吩并[2,3-d]嘧啶-4(3H)-酮类查尔酮化合物,所有化合物结构经过了¹H NMR和MS的确证。初步的生物活性测试表明,目标化合物对乳腺癌MCF-7和MDA-MB-231细胞均显示出抑制活性。      

D-72磺酸树脂催化环己酮肟液相贝克曼重排制己内酰胺

在以二甲亚砜作溶剂,以D-72固体磺酸树脂为催化剂的两相体系中,实现了由环己酮肟液相贝克曼重排制备己内酰胺的反应.主要考察了环己酮肟在固体酸催化剂上的吸附热力学规律以及溶剂、反应温度、反应时间、催化剂用量以及催化剂的重复使用性等因素对重排反应的影响.结果表明,环己酮肟在磺酸树脂上的等温吸附过程符合Langmuir吸附模型,吸附等温线可用Langmuir等温方程和速率方程来描述.在二甲亚砜溶剂中,当反应温度在130℃,催化剂用量为0.5 g(催化剂:环己酮肟=1:2(质量比))的条件下反应6小时,环己酮肟的转化率高达100%,己内酰胺的选择性为86.2%,主要副产物为环己酮.该法对环境无害,反应条件温和,催化剂容易分离和可重复使用等优点.     

钯催化的基于C—H活化合成C-8位芳基取代嘌呤类似物

以芳基硼酸为芳基化试剂,以Pd(PPh3)4为催化剂,Cu I为添加剂,哌啶为碱,在DMF中于125℃反应24 h,通过C—H键的活化反应,合成了系列C-8位芳基取代的嘌呤类似物,为该类化合物的合成提供了新的合成路线.     

漆酚缩甲醛钕聚合物催化合成环己酮乙二醇缩酮

以环己酮和乙二醇为原料,漆酚缩甲醛钕聚合物为催化剂合成了环己酮乙二醇缩酮。实验结果表明：在环己酮100mmol,n(环己酮)：n(乙二醇)=1：1,漆酚缩甲醛钕聚合物3．0g,环己烷7．5mL,回流反应1．0h,目标化合物的收率达74％。     

Development of the scope of a co-mediated O-->C rearrangement reaction

[reaction: see text] In this paper we describe an Al-promoted, Co-mediated O-->C rearrangement reaction of cyclic enol ethers. This process delivers functionalized cyclohexanones with good to excellent levels of diastereocontrol, whereby the product stereochemistry is dependent on the E/Z-stereochemistry of the starting enol ether. The rearrangement process also permits access to highly substituted alpha-spirocyclic cyclohexanones as well as cyclopentanones. The latter rearrangement appears to proceed via an unusual 5-(enolendo)-exo-trig cyclization process.     

Investigation of a stereoselective co-mediated rearrangement reaction

A stereocontrolled approach to alpha-alkyl beta-alkynyl cyclohexanones is reported through a Lewis acid mediated rearrangement reaction of enol ethers bearing an Co-alkyne moiety. The reaction proceeds with high levels of stereoselectivity in the presence of Ti- and B-Lewis acids to provide a range of alpha,beta-disubstituted cyclohexanones in high yield although the products are prone to epimerization at the alpha-position in the presence of the B-promoter system. The potential for an enantioselective variant of this process is outlined, and a rationale for the observed stereochemical trends and detailed structural analyses of the ketone products are described.     

Double Michael addition of nitromethane to divinyl ketones: A remarkably positive effect of additive

An efficient double Michael addition of nitromethane to divinyl ketones was established in good to high yields (75–99%). A wide range of cyclohexanones were obtained with excellent diastereocontrol (up to >20:1 dr) and enantioinduction (91–99% ee) in a one-pot fashion. The involvement of basic additive significantly enhanced the reactivity of this cascade sequence.     

An organocatalytic approach to enantiomerically enriched α-arylcyclohexenones and cyclohexanones

The presence of a p-nitrophenyl group converts acetone into an excellent and versatile nucleophile in organocatalytic processes, able to react with α,β-unsaturated aldehydes affording β-substituted α-arylcyclohexenones via a Michael reaction/aldol reaction/dehydration sequence, which occurs in good yields, ee up to 96% and complete diastereoselectivity. The resulting compounds are excellent synthons for the diastereoselective preparation of a variety of synthetically useful polysubstituted cyclohexanones and derivatives.     

Nouveau mode de synthese des decalones—I

The action of sodium t-amyloxide on 3-(ω-bromobutyl) cyclohexanones (cycloalkylation) yields -decalones. When the 2-position of the initial cyclohexanone is unsubstituted, the reaction yields an equilibrium mixture of isomers (largely trans); but when the cyclohexanone bears a 2-alkyl group, the only product is the cis -decalone with an angular alkyl group. This cycloalkylation thus appears to be stereospecific.

The synthesis of the four -decalones (Va, Vb, V′a, V′b) is described.

The 3-(ω-bromobutyl) cyclohexanones were prepared by the action of the Grignard reagent from the tetrahydropyranyl ether of 4-chloro-1-butanol on the 1,3-cyclohexanedione enol ethers (I, I′), reduction of the resulting 3-(ω-hydroxybutyl) cyclohexenones (II, II′) to the cyclohexanones (III, III′), and finally treatment of the latter with phosphorus tribromide.

A variant is described in which the cycloalkylation is carried out on the 3-(ω-bromobutyl) cyclohex-2-enones (VI).     

Stereoselective reactions. XXXIV. Enantioselective deprotonation of prochiral 4-substituted cyclohexanones using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon

Using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon, enantioselective deprotonation of prochiral 4-substituted cyclohexanones in the presence of excess trimethylsilyl chloride was examined in THF in the absence and in the presence of HMPA. It is shown that enantioselectivity of the reactions decreases as the substituent on the chiral carbon of the chiral lithium amides and the substituent at the 4-position of cyclohexanones become reasonably bulky. An eight-membered cyclic transition state model is proposed for this deprotonation reaction.     

Asymmetric Schmidt reaction of hydroxyalkyl azides with ketones

An asymmetric equivalent of the Schmidt reaction permits stereocontrol in ring expansions of symmetrical cyclohexanones. The procedure involves the reaction of chiral 1,2- and 1,3-hydroxyalkyl azides with ketones under acid catalysis; the initial reaction affords an iminium ether that can be subsequently opened with base. A systematic study of this reaction is reported, in which ketone substrates, chiral hydroxyalkyl azides, and reaction conditions are varied. Selectivities as high as ca. 98:2 are possible for the synthesis of substituted caprolactams, with up to 1,7-stereoselection involved in the overall process. The fact that either possible migrating carbon is electronically identical provides an unusual opportunity to study a ring-expansion reaction controlled entirely by stereoelectronic factors. The mechanism of the reaction and the source of its stereoselectivity are also discussed.     

External chiral ligand-mediated enantioselective Peterson reaction of alpha-trimethylsilanylacetate with substituted cyclohexanones

[reaction: see text] The asymmetric Peterson reaction of an alpha-trimethylsilanylacetate with 4-substituted and 3,5-disubstituted cyclohexanones was mediated by an external chiral tridentate ligand to give the corresponding olefins with an axial chirality in high yields and enantioselectivities of up to 85%.     

A new type of cascade reaction: direct conversion of carbonyl compounds and malononitrile into substituted tetracyanocyclopropanes

A new type of chemical cascade reaction was found: the direct formation of cyclopropanes from carbonyl compounds and C-H acid. The action of free halogen or active halogen containing compounds on a mixture of 1 equiv of carbonyl compound and 2 equiv of malononitrile in a basic alcohol solution results in the formation of substituted 1,1,2,2-tetracyanocyclopropanes in 15-80% yield. The latter are well-known precursors for the different bicyclic heterosystems, among them compounds containing a cyclopropane ring and possessing different types of pharmacological activity. Thus, the new, simple and efficient ‘one-pot’ way to substituted tetracyanocyclopropanes in 50-80% yield was found directly from such simple and reasonable starting compounds as aldehydes, or some cyclic ketones, or substituted cyclohexanones and malononitrile.     

Novel synthesis of enantiomerically pure natural inositols and their diastereomers

A novel synthesis of all stereoisomers of natural inositols has been developed. The key strategy is the stereoselective reduction of substituted β-hydroxy cyclohexanones, which are prepared from a variety of 6-O-acetyl 5-enopyranosides via Ferrier-II reaction catalyzed by palladium chloride. The utility of this approach is demonstrated by the synthesis of D-myo-inositol 1,4,5-tris(phosphate)(IP₃).