Gold-Catalyzed Cycloisomerization of 1,6-Diyne Carbonates and Esters to 2,4a-Dihydro-1H-fluorenes
摘要:
A synthetic method to prepare 2,4a-dihydro-1H-fluorenes efficiently from gold(I)-catalyzed 1,2-acyloxy migration/cyclopropenation/Nazarov cyclization of 1,6-diyne carbonates and esters is described. The suggested reaction pathway provides rare examples of [2,3]-sigmatropic rearrangement in this class of compounds as well as the involvement of an in situ formed cyclopropene intermediate in gold catalysis. Experimental and ONIOM(QM:QM') [our own n-layered integrated molecular orbital and molecular mechanics(quantum mechanics quantum mechanics')] computational studies based on the proposed Au carbenoid species provide insight into this unique selectivity.
Palladium-catalysed atom-economical synthesis of conjugated dienals from terminal acetylenes and acrolein
作者:Zoë Hearne、Chao-Jun Li
DOI:10.1039/c7cc02767b
日期:——
the prevalence of the (E,E)-diene in a wide range of functional molecules. It is shown herein that (E,E)-dienals can be readily prepared in two palladium-catalysed steps from simple, unactivated starting materials; terminalacetylenes and acrolein can be coupled via conjugate addition, followed by alkyne isomerisation. This procedure provides a highly atom-economical, redox-neutral and practical method
Direct Conjugate Addition of Alkynes with α,β-Unsaturated Carbonyl Compounds Catalyzed by NCN-Pincer Ru Complexes
作者:Jun-ichi Ito、Kohei Fujii、Hisao Nishiyama
DOI:10.1002/chem.201203380
日期:2013.1.7
the direct conjugate additions of α,β‐unsaturatedcarbonylcompounds, including ketones, esters, and amides, as well as vinylphosphonates, giving various β‐alkynyl carbonyl and phosphonate compounds. A bis(oxazolinyl)phenyl (phebox)–Ru complex also catalyzes the asymmetric conjugate addition of an alkyne with a β‐substituted, α,β‐unsaturated ketone to produce a chiral β‐alkynyl ketone.
A Simple Nickel Catalyst Enabling an
<i>E</i>
‐Selective Alkyne Semihydrogenation
作者:Niklas O. Thiel、Benyapa Kaewmee、Trung Tran Ngoc、Johannes F. Teichert
DOI:10.1002/chem.201903850
日期:2020.2.3
Stereoselective alkyne semihydrogenations are attractive approaches to alkenes, which are key building blocks for synthesis. With regards to the most atom‐economic reducing agent dihydrogen (H2), only few catalysts for the challenging E‐selectivealkyne semihydrogenation have been disclosed, each with a unique substrate scope profile. Here, we show that a commercially available nickel catalyst facilitates
立体选择性炔烃半氢化是制备烯烃的有吸引力的方法,烯烃是合成的关键组成部分。对于最具原子经济性的还原剂二氢(H 2 ),仅公开了少数用于具有挑战性的E-选择性炔烃半氢化的催化剂,每种催化剂都具有独特的底物范围特征。在这里,我们表明,市售的镍催化剂促进了多种取代内炔的E-选择性炔烃半氢化。这产生了一个简单且广泛适用的整体方案,用于使用 H 2立体选择性地访问E-烯烃,这可以作为通用的合成方法。
Synthesis of Cyclopentenols and Cyclopentenones via Nickel-Catalyzed Reductive Cycloaddition
作者:Aireal D. Jenkins、Ananda Herath、Minsoo Song、John Montgomery
DOI:10.1021/ja206722t
日期:2011.9.14
Strategies for the reductive cycloaddition of enals or enoates with alkynes have been developed. The enal-alkyne cycloaddition directly affords cyclopentenols, whereas the enoate-alkyne cycloaddition affords the analogous cyclopentenones. The mechanism of these processes likely involves formation and protonation of a metallacyclic intermediate. The general strategy provides a straightforward entry
Palladium-catalyzed 1,4-addition of terminal alkynes to unsaturated carbonyl compounds promoted by electron-rich ligands
作者:Lei Zhou、Liang Chen、Rachid Skouta、Huan-feng Jiang、Chao-Jun Li
DOI:10.1039/b805946m
日期:——
The efficient palladium-catalyzed conjugate addition of terminal alkynes to α,β-unsaturated carbonyl compounds has been developed using electron-rich ligands, producing the corresponding γ,δ-alkynyl ketone and γ,δ-alkynyl esters in good yields.