氮自由基环化反应的新进展

三十年前,自由基反应在有机合成中的应用已经非常普遍,但其主要集中在碳自由基的应用上,而杂原子自由基却一直得不到发展.氮自由基环化反应是在近十年内才逐步应用到有机合成中的,它对合成一系列的氮杂环化合物有重要的意义,如内酰胺类、吡咯烷类、生物碱类物质等.从四个方面对氮自由基经环化反应合成多种氮杂环化合物的研究进展做一介绍.     

联炔环化反应研究进展

联炔是一种具有较高反应活性的有机合成中间体,与单炔相比联炔具有共轭结构和更多的反应活性位点,既能够作为四合成子构建单环化合物,也能够发生串联环化反应形成多环化合物,因此成为有机化学家的研究热点。本文综述了近年来联炔环化反应的研究进展,并对该领域未来的发展方向进行了展望。     

自由基加成环化合成含氧或含氮杂环化合物的研究进展

含氧及含氮杂环化合物广泛应用于医药、化工及材料等领域,其合成方法一直备受关注.近年来,自由基加成串联环化策略被认为是构筑含氧及含氮杂环化合物的简洁、高效方法之一.根据杂环种类的不同进行分类,综述了近年来基于自由基加成环化历程合成各类含氧及含氮杂环化合物的研究进展.     

烯烃的自由基环化反应研究进展

综述了近年来烯烃自由基环化反应的研究进展，主要包括通过烯烃的自由基环 化反应合成内酯、内酯胺及一些含杂原子的环状化合物，同时对烯烃自由基环化反 应新进展－－超临界二氧化碳流体作为反应介质也作了阐述。     

二氧噁唑酮参与的环化反应研究进展

胺化反应在合成化学领域占据着重要地位。二氧噁唑酮是一种新型酰基乃春转移试剂,广泛应用于多种类型的胺化反应中。在温和条件下,过渡金属或非金属即可活化二氧噁唑酮,释放出二氧化碳并生成酰基乃春中间体,进而参与到胺化-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,二氧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氧噁唑酮参与的环化反应进行概述。     

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...     

金催化的环化反应与钯催化的炔醇偶联/环化反应相结合用于合成多取代呋喃衍生物:串联反应的应用范围(英文)

开发了一种由金和钯催化π-活化由炔醇合成呋喃衍生物的集成方法.该合成策略是最显著的特点适用于带环辛基的底物,其适用范围比之前报道的有很大扩展.在Sonogashira反应条件下,由相应底物可直接得到环辛基呋喃.Pd在这些反应中起到2个重要作用:底物发生偶联反应的关键催化剂;通过π-活化促进炔醇中间体成环反应.该方法在一步合成3-碘呋喃反应中作用很突出,使通过偶联法进一步官能团化成为可能.我们还将AuBr_3用于多米诺成环/C-H键活化反应和无环前体的成环反应.本文结果表明,在该类成环反应中金和钯催化剂相辅相成.     

三乙胺促进的环丙烯酮和α-卤代异羟肟酸酯的环化反应合成多取代6H-1,3-噁嗪-6-酮

利用环丙烯酮同时具有亲核性、亲电性以及易发生开环反应的特点,实现了三乙胺促进的环丙烯酮和α-卤代异羟肟酸酯类化合物的[3+3]环加成反应,快速构筑了 6H-1,3-噁嗪-6-酮骨架,为噁嗪酮类化合物的合成提供了新的思路.该反应在无金属和温和条件下显示出良好的收率和官能团耐受性,同时适合克级规模制备.     

手性铜催化剂催化的α-重氮酮的环化反应

首次用手性(β-二酮)-铜配合物Cu(dcm)2来催化α-重氮酮的分子内环化反应,获得很高的化学产率和中等程度的光学收率,并考察了底物结构对反应的化学产率和光学收率的影响.     

5-甲基-3-对甲苯基-2-对氯苯硫基-1H茚酮的合成及晶体结构

单质碘与三苯基膦促进的对氯苯亚磺酸钠与1,3-二对甲苯基丙炔-1-醇的自由基加成-分子内氧化碳氢键环化的多步骤串联反应,以70%的产率得到化合物5-甲基-3-对甲苯基-2-对氯苯硫基-1H-茚酮。化合物经¹H NMR、¹³C NMR、 IR和HR-MS等表征,其结构经X-射线单晶衍射分析确证。晶体属于三斜晶系,空间群P-1,晶细胞参数：a=10.7305(7)?,b=13.0234(8)?,c=14.7071(9)?,α=105.289(3)°,β=101.273(3)°,γ=98.623(3)°,V=1899.7(2)?³,Z=4, Dc=1.318 mg/m³,μ=0.320 mm^-1,F(000)=784。结构偏离因子R₁=0.0705, wR₂=0.1903,共收集到8687个独立衍射点,其中I>2σ(I)的可观测点为5542个。     

Radical Alkyne peri‐Annulation Reactions for the Synthesis of Functionalized Phenalenes,Benzanthrenes, and Olympicene

Radical cyclization reactions at a peri position were used for the synthesis of polyaromatic compounds. Depending on the choice of reaction conditions and substrate, this flexible approach led to Bu₃Sn‐substituted phenalene, benzanthrene, and olympicene derivatives. Subsequent reactions with electrophiles provided synthetic access to previously inaccessible functionalized polyaromatic compounds.     

Radical-Induced Cascade Annulation/Hydrocarbonylation for Construction of 2-Aryl-4H-chromen-4-ones

A robust metal- and solvent-free cascade radical-induced C-N cleavage/intramolecular 6-endo-dig annulation/hydrocarbonylation for the synthesis of the valuable 2-aryl-4H-chromen-4-ones is described. This practical synthesis strategy utilizes propargylamines and air as the oxygen source and green carbonylation reagent, in which propargylamines are activated by the inexpensive and available dimethyl 2,2′-azobis(2-methylpropionate) (AIBME) and (PhSe)₂ as the radical initiators. This simple and green protocol features wide substrate adaptability, good functional group tolerance, and amenability to scaling up and derivatizations.     

Synthesis of 1-(2''''-Phenyl)cyclopropyl-2,3-epoxypropan-1-ol as the Radical Precursor for the Kinetic Study of Oxiranylcarbinyl Radical

The oxiranylcarbinyl radical can undergo rapid rearrangement to generate an allyloxy radical (1 2)1. This process has been found application in organic synthesis2. For example, Rawal developed a novel method leading to cis-fused bicyclic compounds based on tandem reactions of oxiranylcarbinyl radical ring opening - intramolecualr H abstraction - radical addition2f. OOk1k-112 On the other hand, the oxiranylcarbinyl radical rearrangement is so rapid that this radical species has never be…     

Synthesis of Cyclic Compounds via Photoinduced Radical Cyclization Cascade of C=C bonds

Cyclic compounds constitute a great important class of substances in the science of medicine and biology, which renders the research on facile and efficient construction of such complex scaffolds from simple starting materials to be hot and appealing. Recently, the radical cascade reaction involving multiple bond formation/cleavage has emerged as an ideal and powerful route to give high‐value cyclic products, along with diminished cost and waste. As a simple and benign methodology, photoredox catalysis offers a readily available access to the generation of radical species. Alkenes have been recognized as one of the most valuable building blocks for the reason they allow installation of different functional groups simultaneously through addition to the C=C bonds. This account summarizes the recent advances in photoinduced radical cascade cyclization to the synthesis of cyclic compounds with C=C bonds working as the initial radical acceptors, and emphasis is put on the related reaction mechanisms.     

可见光诱导的共轭磺酰胺串联脱砜/环化反应

发展了一种可见光诱导的共轭磺酰胺串联脱砜/环化,合成全氟烷基化吲哚酮或α-芳基酰胺的方法。此反应以多氟烷基碘或溴为氟源,在发光二极管蓝光灯照射下,利用面式-三(2-苯基吡啶)合铱催化N-烷基-N-甲基丙烯酰基苯磺酰胺经过串联自由基加成/β-芳基迁移/脱砜环化过程,一步构筑两重碳-碳键,以41%~78%的产率合成了一系列含氟吲哚酮或α-芳基酰胺。此方法底物适用范围广,反应条件温和(室温),催化体系绿色,为具有潜在生理活性的含氟吲哚酮及α-芳基酰胺的合成提供了一条高效、快捷的新途径。     

Tandem Radical Cyclization for the Construction of Difluoro‐Containing Oxindoles and Quinoline‐2,4‐diones

Cu‐catalyzed direct difluoromethylation of activated alkenes through a difluoromethyl radical addition/cyclization to afford difluorinated oxindoles and quinoline‐2,4‐diones has been developed. This method provides convenient access to a variety of oxindoles and quinoline‐2,4‐diones under mild conditions via a proposed tandem radical cyclization process, while tolerating various functional groups well. Moreover, a facile method to construct diverse difluorinated quinoline‐2,4‐diones by visible‐light photoredox catalysis under mild conditions was presented.     

Exo‐Dig Radical Cascades of Skipped Enediynes: Building a Naphthalene Moiety within a Polycyclic Framework

Cascade radical transformations of acyclic precursors open efficient, convenient and atom‐economical access to functionalized compounds of increased structural complexity. This report describes a selective sequence of 5‐exo‐dig and 6‐exo‐dig cyclizations followed by attack at a pendant aromatic moiety and rearomatization.     

Fe(0)催化三氯乙酸烯丙酯的环化反应研究

通过对Fe(O)催化烯烃自由基环化反应的研究，发现以Fe(O)为催化剂催化三氯 乙酸烯丙酯分子内自由基环化反应可以高化学选择性得到五元环内酯产物，反应中 不需加入配体。和大多数自由基反应一样，反应温度与催化剂用量对该反应的转化 率和产率有着很大的影响。     

New Processes for Annulation

Making use of the high propensity of 2-cyano-2-cycloalkenones to undergo conjugate addition with various carbanions and the high reactivity of the ensuing α-cyano ketone system, a number of new annulation processes have been developed recently in our laboratories. As shown in Eq. 1 (n=1) with a specific example, one such process involves the addition of 3-butenylmagnesium bromide, followed by a palladium (II) acetate mediated oxidative cyclization, to facilitate methylenecyclopentane ring for…