Tandem Cyclization of Alkynylmetals Bearing a Remote Leaving Group via Cycloalkylidene Carbenes
摘要:
Treatment of terminal alkynes bearing a remote leaving group with MNR2 (M = Li, Na, K) gives bicyclo[n.3.0]-1-alkenes (n = 3, 4). The tandem cyclization proceeds through a mechanism involving exo-cyclization of an alkynylmetal intermediate and intramolecular C-H insertion of the resulting carbenoid.
摘要 镍(II)钳形络合物[(Me N 2 N)Ni-Cl]用于催化未活化烷基卤化物的烷基-烷基和烷基-芳基的Suzuki-Miyaura偶联反应。9-烷基-9-硼环[3.3.1]壬烷和9-苯基-9-环环[3.3.1]壬烷试剂与卤代烷的偶联以中等至良好的收率实现。该反应可耐受各种有用的官能团,包括酯,醚,呋喃,硫醚,乙缩醛和Boc基团。 镍(II)钳形络合物[(Me N 2 N)Ni-Cl]用于催化未活化烷基卤化物的烷基-烷基和烷基-芳基的Suzuki-Miyaura偶联反应。9-烷基-9-硼环[3.3.1]壬烷和9-苯基-9-环环[3.3.1]壬烷试剂与卤代烷的偶联以中等至良好的收率实现。该反应可耐受各种有用的官能团,包括酯,醚,呋喃,硫醚,乙缩醛和Boc基团。
Mesoporous poly-melamine-formaldehyde (mPMF) – a highly efficient catalyst for chemoselective acetalization of aldehydes
作者:Mei Xuan Tan、Liuqun Gu、Nannan Li、Jackie Y. Ying、Yugen Zhang
DOI:10.1039/c3gc40297e
日期:——
A mesoporous poly-melamine-formaldehyde polymer with a high surface area, good porosity and a high density of amine and triazine functional groups was investigated as a highly efficient hydrogen-bonding catalyst. This porousorganicpolymer was found to be highly effective in catalyzing chemoselective acetalization of aldehydes, without the consumption of any dehydrating agents. The turnover frequency
A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild
Synthesis of Oxacyclic Scaffolds via Dual Ruthenium Hydride/Brønsted Acid-Catalyzed Isomerization/Cyclization of Allylic Ethers
作者:Erhad Ascic、Ragnhild G. Ohm、Rico Petersen、Mette R. Hansen、Casper L. Hansen、Daniel Madsen、David Tanner、Thomas E. Nielsen
DOI:10.1002/chem.201304270
日期:2014.3.17
A ruthenium hydride/Brønsted acid‐catalyzed tandem sequence is reported for the synthesis of 1,3,4,9‐tetrahydropyrano[3,4‐b]indoles (THPIs) and related oxacyclic scaffolds. The process was designed on the premise that readily available allylic ethers would undergo sequential isomerization, first to enol ethers (Ru catalysis), then to oxocarbenium ions (Brønsted acid catalysis) amenable to endo cyclization
据报道,氢化钌/布朗斯台德酸催化的串联序列可用于合成1,3,4,9-四氢吡喃[3,4- b ]吲哚(THPIs)和相关的氧环骨架。该过程被设计的前提是容易得到的烯丙基醚将经历连续的异构化,第一至烯醇醚(RU催化),然后到oxocarbenium离子(布朗斯台德酸催化)适合于内 环化栓系亲核体。该方法不仅为合成THPI的传统oxa-PIctet-Spengler反应提供了有吸引力的替代方法,而且还方便地获得THPI同类物和其他重要的乙环(如乙缩醛)。
Oxidative Coupling Reactions of Grignard Reagents with Nitrous Oxide
作者:Gregor Kiefer、Loïc Jeanbourquin、Kay Severin
DOI:10.1002/anie.201302471
日期:2013.6.10
Catalysis with laughing gas: N2O in combination with transition‐metal catalysts allow the oxidative homo‐ and cross‐coupling of Grignard reagents. The reactions can be performed under mild conditions despite the inert character of N2O.
Copper nanoparticle-catalyzed cross-coupling of alkyl halides with Grignard reagents
作者:Ju Hyun Kim、Young Keun Chung
DOI:10.1039/c3cc46419a
日期:——
A cross-coupling reaction between alkyl bromides and chlorides and various Grignardreagents was carried out in the presence of commercially available copper or copper oxide nanoparticles as a catalyst and an alkyne additive. The catalytic system shows high activity, a broad scope, and good functional group tolerance.