胺催化下的Baylis-Hillman反应

Baylis-Hillman (B-H)反应是在催化剂作用下由活泼烯烃和亲电试剂发生的偶合反应, 其产物是一个具有多官能团的化合物. 胺类催化剂是反应中应用最广泛的一类催化剂. 综述了各种胺催化下的Baylis-Hillman反应的研究进展.     

负载有机膦的合成及其在有机催化领域的应用

有机膦是一类重要的有机催化剂,作为一种亲核催化剂已得到广泛的应用。小分子叔膦作为一种均相催化剂影响产物的分离和催化剂的回收,将膦负载可以弥补上述缺陷。负载叔膦作为一类有机催化剂在近几年才受到关注。本文简要介绍了不同载体负载叔膦的合成方法及应用,综述了其催化Baylis-Hillman、加成、炔酮异构化和羟基保护反应的研究进展,并对研究前景进行了展望。     

Baylis-Hillman反应的研究进展

介绍子一种形成碳碳键的方法－Baylis-Hillman反应及其研究的最新进展。为克服常见Baylis-Hillman反应反应速度慢的缺点,近来人们发展了许多加快反应速度的方法。运用手性底物或手性催化剂等方法来进行不对称Baylis-Hillman反应从而获得手性Baylis-Hillman加成产物。     

手性(硫)脲衍生物在不对称有机催化反应中的应用

手性(硫)脲衍生物是各种亲核试剂对亚胺、醛、缺电子烯烃加成反应的非常有效的有机催化剂之一, 已成功应用于对映选择性催化Strecker反应、Michael加成反应、Mannich反应、Baylis-Hillman反应、Henry反应等一系列重要的有机合成反应. 手性(硫)脲衍生物具有催化活性高、对映选择性和功能基相容性好、易于制备和修饰、适用范围广等优点, 成为近年来研究较多的不对称反应有机催化剂. 对手性(硫)脲衍生物在有机催化不对称合成中的应用研究进展进行了评述.     

磷亲核试剂对缺电子烯烃不对称共轭加成反应的进展

手性膦化合物在不对称催化、药物、材料等领域有着广泛的用途.手性膦可作为配体与金属配位或作为有机催化剂用来催化合成光学活性化合物.含膦亲核试剂对缺电子烯烃的不对称共轭加成反应可以用来直接构建手性膦化合物.总结了该领域近年来的主要研究进展,介绍了几类重要的过渡金属催化剂以及小分子催化剂促进的缺电子烯烃的不对称氢膦化反应.     

可见光诱导有机膦促进脱氧官能化反应研究进展

脱氧偶联反应是有机化学中的重要合成转化,有机膦促进的有机合成反应近年来发展迅速,三苯基膦及其衍生物是有机膦中重要的一类,其在有机合成反应中不仅可以作为配体,而且可以用作脱氧促进剂.最近几年,可见光诱导有机膦促进脱氧偶联反应受到研究者们广泛关注,该类型反应利用有机膦在可见光下经单电子转移后与含氧有机分子形成P—O中间体,随后经脱氧得到高活性自由基物种,并最终完成脱氧偶联,反应底物无需预先官能团化且条件温和.系统地概述了近年来光氧化还原诱导下有机膦促进含氧有机分子脱氧官能化反应的研究进展.     

磷自由基对不饱和键的双官能化反应的研究进展

有机膦化合物在有机反应、光电材料、阻燃材料以及药物化学等研究领域都具有广泛的用途,因而探索更高效、更绿色的方法实现有机膦化合物的合成是有机膦化学工作者的主要目标之一.通过磷自由基与不饱和化合物的双官能团化反应可以在一步反应中实现含磷杂环以及多环化合物的构建.按磷自由基引发方式的不同,对近年来磷自由基与不饱和化合物的双官能团化反应的研究进展进行了综述.     

碱性离子液体的合成及其在Baylis-Hillman 反应中的应用

采用正交实验优化合成了碱性离子液体氢氧化1-丁基-4-二甲氨基吡啶盐, 以其为反应溶剂, 在催化剂DABCO(1,4-二氮杂二环[2.2.2]辛烷)作用下进行了芳香醛与丙烯酸甲酯的Baylis-Hillman 反应研究. 实验结果表明, 在该离子液体的存在下, 芳香醛与丙烯酸甲酯以较快的反应速度和较高产率生成目标化合物. 在此基础上, 进一步研究了水-离子液体复合体系对Baylis-Hillman 反应的影响, 取得了更快的速率及更高的产率.     

Pd-N-杂环卡宾化合物催化的Heck反应、Suzuki反应进展

Pd催化的C—C键偶联反应是形成碳—碳单键的重要反应之一.传统上,使用膦化合物为配体来调整催化活性及选择性.但大多数Pd-膦化合物对空气稳定性差,容易被氧化;在溶液中易于解离出膦配体而降低催化剂稳定性,通常需要给反应体系中加入较多的膦配体以保持催化剂的稳定性和活性.1991年发现的稳定N-杂环卡宾(NHC)类配体具有富含电子、给电子能力强,对金属配位能力强,结构易修饰等特点,使得金属-NHC化合物成为金属有机化学、催化等领域研究新的焦点.Pd-NHC化合物已经可催化多类有机反应,是继传统Pd-膦催化剂外的又一类高效催化剂.综述了近年来不同结构的NHC如单齿简单NHC、双齿NHC、含其它配位原子的NHC等配体与Pd的配合物在Heck反应、Suzuki反应等偶联反应中的应用.     

水溶性铑膦配合物催化烯烃氢甲酰化反应研究进展

 水/有机两相体系中水溶性铑膦配合物催化的烯烃氢甲酰化反应由于具有环境友好和催化剂容易分离等优点而受到广泛关注. 其中水溶性催化剂体系已经用于丙烯氢甲酰化反应制备丁醛的工业化生产. 然而, 长链烯烃在含有催化剂的水相中溶解性较差, 反应速率较慢. 综述了有关加速水/有机两相体系中长链烯烃氢甲酰化反应的方法和进展, 包括使用具有表面活性的膦配体, 以及在催化体系中添加环糊精和表面活性剂等促进剂. 另外, 还讨论了有关内烯烃氢甲酰化反应和提高直链醛选择性的方法.     

新型N-P配体的合成、表征及其在氢转移反应中的应用

利用2,3-二(二苯膦氧基)-1,3-丁二烯与胺的迈克尔加成反应,合成了单胺基及环胺基改性的有机氧化膦,经有机硅烷还原,制备出胺基取代的膦配体,所得化合物经NMR及单晶X射线衍射分析.考察了所得配体与Ru(PPh3)3Cl2组成的催化体系在苯乙酮氧转移反应中的催化活性,发现氧化膦与Ru原位形成的催化剂比其还原态的三价膦组成的催化剂催化活性还高,二胺基取代的二氧化膦配体具有较高的催化活性,TON可达273.而采用先制备催化剂再催化反应时配体6的钌络合物催化活性TON可达352.     

Regioselective synthesis and structural studies of substituted gamma-hydroxybutenolides with use of a tandem Baylis-Hillman/singlet oxygenation reaction

The scope and limitations of a regioselective synthesis of either alpha- or beta-substituted gamma-hydroxybutenolides from 3-furfural and enones are described. The sequence features a Baylis-Hillman reaction followed by singlet oxygen oxidation with use of either an amine base or TBAF as the regioselectivity switches. Structural studies in solution on some of the resulting gamma-hydroxybutenolides are also reported.     

Unexpected hydrodeiodo Sonogashira-Heck-Casser coupling reaction of 2,2'-diiodobiphenyls with acetylenes

2,2'-Diiodobiphenyl-4,4'-dicarboxylic acid dimethyl ester (3) undergoes either a ring-closure reaction with phenylacetylene to give 4 or hydrodeiodo phenylethynylation to give 5 under the catalytic conditions of Pd(OAc)(2)/CuI/phosphine in amines. In these reactions, the amine and the phosphine ligands play important roles in controlling the reactivity. Among the ligands we used, tris(o-tolyl)phosphine is the best ligand for hydrodeiodo phenylethynylation, while the bidentate phosphine ligand retards both of the reactions. On the basis of our results, we propose that 5 is formed through a fast hydrodeiodination, followed by a Sonogashira phenylethynylation. The results of the deuterium labeling experiments show that proton exchange between the acetylenic proton and the alkyl protons of amine occurs effectively under the reaction conditions. In addition, the hydrogen that replaces the iodide in the hydrodeiodination process arises mainly from the acetylenic proton.     

Switching the reactivity of dihydrothiopyran-4-one with aldehydes by aqueous organocatalysis: Baylis-Hillman, aldol, or aldol condensation reactions

An aqueous medium containing catalytic amounts of a tertiary amine was employed to direct the chemoselectivity of the reaction of aldehydes with 1a. With DBU, 2 was formed at room temperature as a rare exemplary of Baylis-Hillman reactions in heterocyclic enones. DABCO alternated the pathway toward an aldol reaction to form syn/anti mixtures of 3 with the syn isomers being the major products. With Et(3)N, aldol condensation dominated.     

Titanium(IV) chloride and the amine-promoted baylis-hillman reaction

In the Baylis-Hillman reaction, we found that, when the reactions of arylaldehydes with methyl vinyl ketone were carried out at <-20 degrees C using a catalytic amount of amine as a Lewis base in the presence of titanium(IV) chloride, the chlorinated compounds 1 could be obtained as the major product in very high yields for various arylaldehydes. In addition, acrylonitrile could undergo the same reaction to give the corresponding chlorinated product in moderate yield.     

An easy access to functionalized allyl dithiocarbamates from Baylis-Hillman adducts in water

A facile and direct highly stereoselective synthesis of [E]- and [Z]-allyl dithiocarbamates has been accomplished from acetates of Baylis-Hillman (BH) adducts in catalyst-free one-pot three-component coupling reactions of carbon disulfide and amine in water under a mild and green procedure with high yields. The reaction pathway involves the nucleophilic displacement (SN2′) of BH acetates by dithiocarbamate anions. The utility of these allyl dithiocarbamates has also been demonstrated in heterocyclic chemistry. © 2009 Elsevier Science. All rights reserved     

Nonenzymatic acylative kinetic resolution of Baylis-Hillman adducts

The first efficient nonenzymatic acylative kinetic resolution of Baylis-Hillman adducts is reported. Chiral pyridine catalyst 1a and an optimized analogue 1e are capable of promoting the synthetically useful enantioselective acylation (the efficiency of which is outstanding for sp(2)-sp(2) carbinol substrates, s = 3.5-13.1, ee up to 97%) of Baylis-Hillman adducts derived from recalcitrant precursors which are currently difficult to synthesize utilizing benchmark asymmetric Baylis-Hillman reaction catalyst technology. A novel one-pot synthesis-kinetic resolution process involving a DBU-catalyzed Baylis-Hillman reaction and subsequent 1e/DBU-mediated enantioselective acylation has also been developed.     

Mechanistic Study of the Role of Primary Amines in Precursor Conversions to Semiconductor Nanocrystals at Low Temperature

Primary alkyl amines (RNH₂) have been empirically used to engineer various colloidal semiconductor nanocrystals (NCs). Here, we present a general mechanism in which the amine acts as a hydrogen/proton donor in the precursor conversion to nanocrystals at low temperature, which was assisted by the presence of a secondary phosphine. Our findings introduce the strategy of using a secondary phosphine together with a primary amine as new routes to prepare high‐quality NCs at low reaction temperatures but with high particle yields and reproducibility and thus, potentially, low production costs.     

Toward understanding the scope of Baylis-Hillman reaction: synthesis of 3-(2- hydroxyphenyl)indolin-2-ones and polycyclic fused furans

A facile one-pot synthesis of 3-(2-hydroxyphenyl)indolin-2-ones has been developed via the TiCl₄-mediated Baylis-Hillman (B-H) reaction of N-substituted isatins and cyclohex-2-enone, followed by treatment of the in situ generated B-H alcohols with aq HBr. Baylis-Hillman reaction of aromatic cyclic 1,2-diones with cycloalk-2-enones under the influence of TiCl₄ has been successfully performed and the resulting Baylis-Hillman adducts have been conveniently transformed into pentacyclic and hexacyclic fused furan derivatives.