二噁唑酮参与的环化反应研究进展

氨化反应在合成化学领域占据着重要地位。二噁唑酮是一种新型酰基氮烯转移试剂,广泛应用于多种类型的氨化反应中。在温和条件下,过渡金属或非金属即可活化二噁唑酮,释放出二氧化碳并生成酰基氮烯中间体,进而参与到氨化-环化反应中。该策略为构建噁唑、喹唑啉和喹诺酮等杂环化合物提供了新的思路。近年来,二噁唑酮参与的环化反应受到越来越多研究者的关注,并且取得了重要进展。本文从不同的催化体系着手就近年来二噁唑酮参与的环化反应进行概述。     

过渡金属催化苯并-2,1-异噁唑的环化反应研究进展

含氮杂环常见于天然产物、药物和材料分子中,也是人体内多种氨基酸和激素的主要结构单元.近年来,苯并-2,1-异噁唑作为有效的胺化试剂被广泛应用于胺化、环化反应中.尤其是过渡金属催化的苯并-2,1-异噁唑的胺化-环化反应,已经成为构建C—N键和合成含氮杂环的强有力工具,也引起越来越多研究者的兴趣和关注.本文概述了近年来过渡金属催化苯并-2,1-异噁唑环化反应的相关研究,并对该研究领域存在的问题和难点进行简要的展望.     

3-丙烯酰基-1,3-噁唑烷-2-酮的合成

3-α，β-不饱和酰基-1，3-噁唑烷-2-酮在烷基化及Diels-Alder等反应中在手性催化剂的存在下，产物都有较高的对映选择性。但3-丙烯酰基-3，3-噁唑烷-2-酮极易聚合，现有制备方法结果均不理想。本文将丙烯酸与丙烯酰氯在三乙胺的存在下生成酸酐，再在无水氯化锂的作用下与1，3-噁唑烷-2-酮在室温反应，反应结束后直接将反应混合物通过硅胶柱色谱进行层析分离得到3-丙烯酰基-1，3-噁唑烷-2-酮，产率达83％。合成路线如下：     

以二氧化碳为C1合成子的羧基化/环化反应研究进展

二氧化碳具有价廉易得、储量丰富及无毒等优点,在有机合成反应中是一种理想的C1合成子.近年来,以二氧化碳作为羰基/羧基源,通过环化反应,特别是多组分环化反应构建含羰基杂环化合物,已经取得了重要的研究进展.主要总结了利用含氮、氧亲核原子的试剂与常压条件下二氧化碳的环化反应构建苯并噁嗪、环碳酸酯、内酰胺、2,4-二噁唑啉酮等含羰基杂环结构的工作;其次,也总结了利用含碳亲核原子的试剂与二氧化碳羧基化反应的相关工作.     

3-取代胺甲基-5-连三唑基-1,3,4-噁二唑-2-硫酮的合成

2-苯基-1,2,3-三唑-4-甲酰肼(1)在CS_2/KOH作用下环化得到5-(2-本基-1,2,3-连三唑-4-基)-1,3,4-噁二唑-2-硫酮(2),2经Mannich反应合成得到标题化合物3-取代胺甲基-5-(2-本基-1,2,3-连三唑-4-基)-1,3,4-噁二唑-2-硫酮(3)。     

利伐沙班中间体的合成工艺研究

本文以溴苯为起始原料,经Ullmann反应、N-酰基化、吗啉酮环合、芳环硝基化、芳硝基还原、2-噁唑烷酮环合共六步反应制得了利伐沙班的关键中间体,所得目标化合物经质谱、核磁共振氢谱确认,总收率达到44.50%。     

新型六氢山酮素拼接异噁唑双螺环氧化吲哚类化合物的合成

以色酮-氧化吲哚合成子1与氧化吲哚3-烯烃硝基异噁唑2,在催化剂DABCO催化下,在氯仿中发生双Michael加成环化反应,合成了7个未见文献报道的六氢山酮素拼接异噁唑双螺环氧化吲哚类化合物3a~3g,产率78%~92%,dr值10/1~15/1,其结构经¹H NMR, ¹³C NMR和HR-MS（ESI-TOF）表征。     

碘/碘化亚铜介导的烯酰胺氧化环化反应合成多取代噁唑

开发了一种简洁、高效的碘/碘化亚铜介导分子内氧化性C—O键构建反应用于噁唑类化合物的合成.在优化的反应条件下,通过对易得的烯酰胺类底物进行氧化环化可以合成各种芳基、烷基、酰胺基、酯基以及酰基等基团取代的噁唑衍生物.     

含二苯联噁二唑大环多胺及其配合物的合成

用2,5-双-(间甲酰基苯基)-1,3,4-噁二唑和相应的二胺,经[2 2]缩合环化反应,合成了三个含二苯联噁二唑的新型大环多胺4、5和7以及5的钡络合物。     

1,8-二氮杂二环十一碳-7-烯(DBU)立体选择性催化合成噁唑啉-2-(硫)酮衍生物

以1,8-二氮杂二环十一碳-7-烯(DBU)为催化剂,在无其它金属催化条件下,炔丙醇与异氰酸酯(或硫氰酸酯)进行亲核加成/环化反应,合成了一系列多取代的噁唑烷-2-(硫)酮衍生物,收率为75%~95%.该反应经5-exo-dig环化机制,高度立体选择性地得到Z-式芳亚甲基取代产物,为噁唑啉酮的骨架合成提供了简单快速的合成方法.     

Synthesis of novel pyranoquinones using an acyl radical cyclization strategy

The thiol-catalysed cyclization of acyl radicals generated directly from benzaldehyde precursors has been investigated. Hindered β-benzyloxyacrylates cyclize efficiently providing a tin-free radical cyclization approach to the serine/threonine kinase AKT inhibitor frenolicin B, whilst γ-aryloxy crotonates give good yields of benzopyran-4-ones. This method is applied to the synthesis of a novel tetracyclic analogue of the pyranonaphthoquinone antibiotics.     

Visible‐Light‐Promoted Cascade Radical Cyclization: Synthesis of 1,4‐Diketones Containing Chroman‐4‐One Skeletons

A visible‐light‐induced cascade radical cyclization of aroyl chlorides with 2‐(allyloxy)‐benzaldehyde derivatives has been developed. The method takes advantages of unactivated C=C bonds as the acyl radical acceptors and offers a mild and green approach for the synthesis of 1,4‐diketones bearing biologically important chroman‐4‐one skeletons with moderate to good yields.     

One‐Pot Tandem Michael Addition/Enantioselective Conia‐Ene Cyclization Mediated by Chiral Iron(III)/Silver(I) Cooperative Catalysis

The first one‐pot tandem Michael addition/enantioselective Conia‐ene cyclization of N‐protected prop‐2‐yn‐1‐amines with 2‐methylene‐3‐oxoalkanoates promoted by chiral iron(III)/silver(I) cooperative catalysts has been developed. Alkyl 4‐methylenepyrrolidine‐3‐acyl‐3‐carboxylates, which can be transformed into β‐proline derivatives, are obtained in high yield with high enantioselectivity.     

有机催化不对称Michael/环化串联反应的研究进展北大核心CSCD

串联反应能够减少反应步骤、简化操作、降低成本、实现高效率转化,符合原子经济性和绿色化学理念.特别是有机催化的不对称串联环化反应以一锅法连续催化多个化学反应,为高效合成多手性中心环状结构提供了新方法.不对称Michael/环化串联反应是构建光学活性状化合物的常用方法之一,近些年,各种有机小分子催化剂应用于不对称Michael/环化串联反应的报道不断增加,并且取得了重大进展.我们根据不同的催化剂类型综述了近5年来关于不对称Michael/环化串联反应的研究进展,并对有机催化不对称Michael/环化串联反应的发展趋势进行了展望.     

Carboxylic acids as substrates in homogeneous catalysis

In organic molecules carboxylic acid groups are among the most common functionalities. Activated derivatives of carboxylic acids have long served as versatile connection points in derivatizations and in the construction of carbon frameworks. In more recent years numerous catalytic transformations have been discovered which have made it possible for carboxylic acids to be used as building blocks without the need for additional activation steps. A large number of different product classes have become accessible from this single functionality along multifaceted reaction pathways. The frontispiece illustrates an important reason for this: In the catalytic cycles carbon monoxide gas can be released from acyl metal complexes, and gaseous carbon dioxide from carboxylate complexes, with different organometallic species being formed in each case. Thus, carboxylic acids can be used as synthetic equivalents of acyl, aryl, or alkyl halides, as well as organometallic reagents. This review provides an overview of interesting catalytic transformations of carboxylic acids and a number of derivatives accessible from them in situ. It serves to provide an invitation to complement, refine, and use these new methods in organic synthesis.     

CCC-N-heterocyclic carbene pincer complexes: Synthesis, characterization and hydroamination activity of a hafnium complex

Our methodology for the stoichiometric preparation of CCC-NHC pincer complexes of Zr has been extended to Hf. The CCC^Bu-NHC pincer Hf complex has been characterized by X-ray crystal structure analysis. Catalytic activity in the intramolecular hydroamination/cyclization of unactivated alkenes is reported and compared to the recently reported Zr analog. An improved, scaled-up CuO-catalyzed aryl amination of 1,3-dibromobenzene and an improved salt formation methodology for preparation of bis(butyl-imidazolium)benzene are reported also.     

Copper‐Catalyzed α‐Amination of Phosphonates and Phosphine Oxides: A Direct Approach to α‐Amino Phosphonic Acids and Derivatives

A direct approach to important α‐amino phosphonic acids and its derivatives has been developed by using copper‐catalyzed electrophilic amination of α‐phosphonate zincates with O‐acyl hydroxylamines. This amination provides the first example of C? N bond formation which directly introduces acyclic and cyclic amines to the α‐position of phosphonates in one step. The reaction is readily promoted at room temperature with as little as 0.5 mol % of catalyst, and demonstrates high efficiency on a broad substrate scope.     

Direct Carbocyclizations of Benzoic Acids: Catalyst‐Controlled Synthesis of Cyclic Ketones and the Development of Tandem aHH (acyl Heck–Heck) Reactions

The formation of exo‐methylene indanones and indenones from simple ortho‐allyl benzoic acid derivatives has been developed. Selective formation of the indanone or indenone products in these reactions is controlled by choice of ancillary ligand. This new process has a low environmental footprint as the products are formed in high yields using low catalyst loadings, while the only stoichiometric chemical waste generated from the reactants in the transformation is acetic acid. The conversion of the active cyclization catalyst into the Hermman–Beller palladacycle was exploited in a one‐pot tandem acyl Heck–Heck (aHH) reaction, and utilized in the synthesis of donepezil.     

手性咪唑啉酮离子液体的合成

手性离子液体在不对称合成中作为手性诱导物具有广泛的应用前景.手性咪唑啉酮类催化剂是有机胺催化剂中重要的一种类型,是不对称有机催化领域研究的热点之一.从绿色化、经济化的角度出发,以天然手性源物质L-酪氨酸为起始原料,经过酯化、胺解、关环、[3+2]环加成等多步反应合成了7种未见文献报道的手性咪唑啉酮类离子液体,并通过1H NMR,13C NMR,ESI-MS,[α]20D,DSC,TGA等方法对其结构及性质进行了表征.     

Iron-catalyzed C–H amination and its application in organic synthesis

Transition-metal-catalyzed direct C–H bond amination is an attractive strategy in preparation of nitrogen containing molecules which are common in naturally occurring and pharmaceutically important compounds. Comparing to the precious metals commonly used in this reaction, non-precious metals such as iron are abundant in earth, relatively low toxic, and more biocompatible, which meet the increasing demand for environmentally benign and sustainable chemical processes. In this review, we described the development in iron catalyzed C–H bond amination reactions from historical landmarks to recent achievements, and placed emphasis on their applications in organic synthesis, i.e. natural product synthesis and/or modification.