2,3-联烯醇及其衍生物的反应

2,3-联烯醇是一类含1,2-二烯官能团和羟基的化合物, 具有很高的反应活性, 它及其衍生物是一类重要的联烯化合物. 概述了2,3-联烯醇及其衍生物的反应, 包括2,3-联烯醇在过渡金属催化下的自身异构环化反应、钯催化的偶联反应、钌催化的环羰基化反应、不同条件下不同方式的扩环反应、亲电试剂参与的反应、分子内环加成反应、自由基反应等和2,3-联烯醇衍生物在零价钯催化下基于亚甲基-π-烯丙基钯中间体生成联烯或1,3-共轭二烯的区域选择性反应, S_N2'类型的加成-消除反应, 二价钯催化下的分子内环化反应以及重排反应等.     

从炔烃衍生物出发的有机合成方法学

研究了过渡金属催化的炔烃衍生物的异构化反应.从α,β-炔酮、2-炔酸酯和2-炔酸酰胺可以生成相应的(E,E)-共轭双烯酮、双烯酸酯和双烯酸酰胺.首次从2-炔醇异构化为相应的2-烯酮或2-烯醛.这一反应具有简单、高产率和立体选择性的优点.假设反应烯经过连二烯中间体,然后再异构化成产物,这一反应提供了方便而有潜在应用价值的方法以制备天然产物合成时的重要中间体.     

手性环丙烯构建策略用于对映选择性合成偕二氟亚甲基三元环化合物

作为最小的不饱和环状分子,环丙烯独特的刚性结构和多变的反应活性吸引了化学家的研究兴趣.自1922年Demjanov[1]报道了环丙烯化合物的首例合成以来,现已发展了一系列环丙烯的合成方法.手性环丙烯的合成是通过炔烃和重氮化合物的[2+1]不对称环加成反应.根据底物的不同,这些不对称环加成反应可以分为四类:(a)末端炔烃和单取代重氮化合物的反应,(b)末端炔烃和双取代重氮化合物的反应,(c)非末端炔烃和双取代重氮化合物的反应,(d)非末端炔烃和单取代重氮化合物的反应.在这四类反应中,末端炔烃和单取代重氮化合物的不对称反应相对容易进行.1992年,Doyle和Müller等[2]报道了手性铑催化剂[Rh2(5R-MEPY)4]促进的末端炔烃和重氮醋酸酯之间的不对称环丙烯基化反应(Scheme 1a).随后各种手性催化剂包括[Rh2(OAc)-(DPTI)3][3]、Ir(salen)衍生物[4]和[Co(3,5-diMes-Chen-Phyrin)][5]等被先后报道用于末端炔烃和单取代重氮化合物的不对称[2+1]环加成反应.     

金催化分子间炔烃的氮烯转移反应合成含氮杂环化合物

含氮杂环是很多天然产物、生物医药活性物种、光电新材料等的重要结构单元,也是有机合成中非常重要的合成子.主要介绍金催化分子间炔烃与氮烯前体的反应,合成多取代氮杂环化合物.在该类反应中,炔烃经金催化剂活化后,与各种不同的氮烯前体反应,以一种高效、快捷的转化模式构建多官能团化的含氮杂环化合物.     

联烯的自由基反应

联烯是含有1,2-丙二烯官能团的重要化合物,具有很高的反应活性.概述了联烯及其衍生物的自由基反应,包括分子间自由基链加成和分子间-分子内自由基串联加成反应,及其在天然产物中的应用.联烯进行分子间自由基链加成反应时,自由基对联烯的加成既可发生在中间碳原子上,也可发生在末端碳原子上,主要取于所形成中间体的稳定性,空间效应、电负性和溶剂等因素也有影响.一般以碳为中心的自由基(如CH3·,CCl3·等)易进攻末端碳原子,而以杂原子为中心的自由基(如Br·,RS·,ArSO2·等)易进攻联烯的中心碳原子.联烯及其衍生物也易与烯烃、联烯、烯炔和乙烯酮进行[2 2]环加成反应,还可以与卡宾环丙烷化,这些反应都是通过自由基机理进行的.     

亮点介绍

手性路易斯碱催化的α-乙酰氧基-β-烯胺酯的不对称氢化硅烷化反应:光学活性α-羟基-β-氨基酸衍生物的合成Angew.Chem.Int.Ed.2011,50,7304～7307光学活性的α-羟基-β-氨基酸片段广泛存在于天然产物以及生理活性物质中,是一类非常重要的化合物,其中最具代表性的就是紫杉醇侧链及其类似物.因此,光学活性α-羟基-β-氨基酸衍生物的合成引起了广泛而持久的兴趣,多年来众多研究小组发展了多种高效、高选择性的合成方法.最近,中国科学院成都有机化学研究所张晓梅等设计了一类α-乙酰氧基-β-烯胺酯底物1,并以新型路易斯碱催化剂2催化其不对称氢化硅烷化反应,以较高的对映选择     

Cu(Ⅰ)催化的不对称直接插炔Aldol反应构建手性2,3-联烯醇

手性联烯是一类具有丙二烯结构的轴手性化合物,不仅广泛存在于众多天然产物[1]、药理活性分子及功能材料中[2],还是有机化学中非常重要的合成砌块[3].其中,含有一个中心手性和轴手性的2,3-联烯醇结构是类胡萝卜、素类、萜类以及溴代联烯天然产物的核心片段,表现出广泛的生理活性,并且由于同时含有联烯和醇羟基官能团,也具有多样的反应化学.因此,2,3-联烯醇的不对称合成具有重要的研究意义.     

过渡金属催化偕二溴烯烃衍生物的偶联反应（英文）

偕二溴烯烃衍生物是有机化学中非常重要的合成工具,已被广泛应用于功能化分子的构建.在过去几十年中,金属催化(如铂、铜、银、金、镍)与偕二溴烯烃衍生物的转化已发展成为合成炔烃、色烯、吲哚、苯并吲哚及苯并噻吩等具有重要生理活性的苯并稠合杂环的有力工具.总结了自2013年以来过渡金属催化的偕二溴烯烃衍生物转化的研究进展.     

利用碳碳叁键断裂重组反应合成2,4,4-三氯萘-1(4H)-酮衍生物

以炔烃-联烯酮为原料,水作为亲核试剂,通过N-氯代丁二酰亚胺(NCS)介导的[2+2]环加成和碳碳叁键断裂重组反应合成了18个2,4,4-三氯萘-1(4H)-酮衍生物,产率为55%～88%.所得产物的结构经NMR和IR以及HRMS等表征,其中目标产物2e的结构经X单晶分析确认.该反应条件温和、操作简单、无需金属催化剂且产率良好,为合成官能化的1-萘酮衍生物提供了一种新的高效的合成策略.     

铜催化共轭乙烯基联烯硅和1,3-二烯硅合成

在温和反应条件下,铜催化间隔烯炔衍生物与有机硅烷硼酸酯化合物发生反应,通过调控有机硅硼试剂的用量,以较高产率分别制备共轭乙烯基联烯硅和1,3-共轭二烯硅产物.该方法为制备多取代立体选择性官能团化联烯和1,3-共轭二烯产物提供了简单、高效的合成工具.     

Theoretical study of the reaction mechanisms involved in the thermal intramolecular reactions of 1,6-fullerenynes

Substitution of a H atom by an alkyl group on the terminal carbon of the alkyne moiety of 1,6-fullerenynes has a strong impact on the products of the reaction undergone by this species after thermal treatment. While the reaction of 1,6-fullerenynes bearing an unsubstituted alkyne moiety results in the cycloaddition of the alkyne group to the fullerene double bond leading to cyclobutene-fused derivatives, the presence of an alkyl substituent leads to the formation of allenes. In the present work, we have performed an exhaustive theoretical analysis of all possible reaction mechanisms leading to cyclobutene-fused derivatives and allenes to offer an explanation of the reactivity differences observed. The results obtained show that formation of cyclobutene-fused derivatives occurs through a stepwise diradical reaction mechanism, while allene formation proceeds through a concerted way involving an uncommon intramolecular ene process. For the 1,6-fullerenynes bearing a substituted alkyne, the ene reaction path leading to allenes has an energy barrier somewhat lower than the stepwise diradical mechanism for the cyclobutene-fused derivative formation, thus explaining the outcome of the reaction.     

Intramolecular ene reaction of 1,6-fullerenynes: a new synthesis of allenes

[Structure: see text] Thermal treatment of 1,6-fullerenynes bearing an alkyl group on the terminal carbon of the alkyne moiety leads quantitatively to new allenes through a reaction mechanism involving an intramolecular ene process. This reaction outcome is in contrast to that recently found for free terminal alkynes which form cyclobutene derivatives through a [2+2] cyclization mechanism.     

Au(I)-catalyzed annulation of enantioenriched allenes in the enantioselective total synthesis of (-)-rhazinilam

Highly stereoselective Au(I)-catalyzed pyrrole additions to enantioenriched allenes afford a unique entry to optically active heterocycles. Asymmetric quaternary carbons can be installed with concurrent heterocycle annulation utilizing this methodology. The enantioenriched allenes are conveniently obtained by catalytic asymmetric acyl halide-aldehyde cyclocondensations and SN2' ring opening of the resulting enantioenriched beta-lactones. An enantioselective total synthesis of (-)-rhazinilam highlights the potential utility of this reaction technology in target-oriented synthesis.     

Direct and stereospecific synthesis of allenes via reduction of propargylic alcohols with Cp2Zr(H)Cl

Allenes can be synthesized via the direct SN2' addition of hydride to propargylic alcohols. Previous examples of this approach, however, have involved harsh reaction conditions and have suffered from incomplete transfer of central chirality to axial chirality. Here we show that Cp2Zr(H)Cl can react with the zinc or magnesium alkoxides of propargylic alcohols to generate allenes in good yield and in high optical purity. Dialkyl-, alkyl-aryl-, and diaryl-allenes are accessible by this method. Furthermore, the reaction can provide silyl-substituted allenes, trisubstituted allenes, and terminal allenes.     

Cobalt‐Catalyzed Intermolecular [2+2] Cycloaddition between Alkynes and Allenes

An intermolecular [2+2] cycloaddition reaction between an alkyne and an allene is reported. In the presence of a cobalt(I)/diphosphine catalyst, a near equimolar mixture of the alkyne and allene is converted into a 3‐alkylidenecyclobutene derivative in good yield with high regioselectivity. The reaction tolerates a variety of internal alkynes and mono‐ or disubstituted allenes bearing various functional groups. The reaction is proposed to involve regioselective oxidative cyclization of the alkyne and allene to form a 4‐alkylidenecobaltacyclopentene intermediate, with subsequent C?C reductive elimination.     

Highly Selective Barbier‐Type Propargylations and Allenylations Catalyzed by Titanocene(III)

The alkyne functional group is found in many bioactive natural products and is the key to many important chemical transformations developed over recent years. Moreover, allenes have recently gained relevance as versatile reagents in organic synthesis. Mild, catalytic methods to enable the selective introduction of either alkyne or allene motifs into organic molecules are very valuable but, as yet, quite scarce. We describe an extremely mild and selective method for either the propargylation or allenylation of carbonyl compounds catalyzed by the abundant, safe, and inexpensive metal titanium. These reactions can selectively provide homopropargylic alcohols from aldehydes and ketones or α‐hydroxy‐allenes from aldehydes. The mechanisms involved were also investigated.     

Organocatalytic Formation of Chiral Trisubstituted Allenes and Chiral Furan Derivatives

A novel reaction that provides chiral allenes by amino catalytic activation of either aldehydes or α,β‐unsaturated aldehydes for reaction with alkynyl‐substituted enones is presented. The reaction forms a variety of trisubstituted allenes in high yields and with excellent stereoselectivities. The utility of the reaction concept is demonstrated by the synthesis of chiral furan derivatives in high yields and stereoselectivities.     

Synthesis of polyfunctional allenes by successive copper-mediated substitutions

Readily available 1,1-dichloro-2-alkynes are versatile starting materials for the synthesis of polyfunctionalized allenes. They can be prepared from commercially available terminal alkynes in a two-step procedure. The Cu-mediated reaction of several 1,1-propargylic derivatives with functionalized alkyl, benzylic, or allylic zinc reagents proceeds exclusively with S(N)2' selectivity and allows a rapid and efficient synthesis of functionalized chloroallenes. These chloroallenes undergo a novel Cu(I) -catalyzed substitution reaction with functionalized arylmagnesium reagents with excellent S(N)2 selectivity to give trisubstituted polyfunctionalized allenes. The functional group tolerance is excellent and functionalities, such as cyano, keto, ester, phosphate, trifluoromethyl, and halogens, are well tolerated.     

Allylstannanes and vinylstannanes from stannylcupration of C-C multiple bonds. Recent advances and applications in organic synthesis

The stannylcupration of allenes and alkynes has emerged as a powerful tool for the synthesis of allyl- and vinylorganostannanes. The regio- and stereoselectivity of this reaction depends upon the nature of the cuprate, the temperature and the structure of the allene or alkyne. The versatility and synthetic scope of the tin-synthons thus obtained is very wide. These intermediates have been employed as precursors in the key step of the stereoselective synthesis of many natural products, heterocycles or conjugated polyenes. This tutorial review shows a general survey of the recent advances in this area together with the contribution of our lab to this field.     

Intermolecular hydrophosphination of alkynes and related carbon[bond]carbon multiple bonds catalyzed by organoytterbiums

Intermolecular hydrophosphination of alkynes with diphenylphosphine is catalyzed by a Yb[bond]imine complex, [Yb(eta(2)-Ph(2)CNPh)(hmpa)(3)], to give alkenylphosphines and phosphine oxides after oxidative workup in good yields under mild conditions. This reaction is also applicable to various carbon[bond]carbon multiple bonds such as conjugated diynes and dienes, allenes, and styrene derivatives. Regio- and stereoselectivity and the scope and limitation of the present reaction clearly differ from those of the corresponding radical reaction. Instead, the reaction takes place through insertion of alkynes to a Yb[bond]PPh(2) species, followed by protonation. In fact, the Yb[bond]phosphido complex, [Yb(PPh(2))(2)(hmpa)(3)], is obtained from the imine complex and phosphine, which exhibits similar catalyst activity for the hydrophosphination. The empirical rate law is nu = k[catalyst](2) [alkyne](1)[phosphine](0) at least under the standard conditions.