scholarly journals Axially chiral racemic half-sandwich nickel(ii) complexes by ring-closing metathesis

2017 ◽  
Vol 46 (12) ◽  
pp. 3805-3808 ◽  
Author(s):  
Włodzimierz Buchowicz ◽  
Łukasz Banach ◽  
Radosław Kamiński ◽  
Piotr Buchalski
Keyword(s):  
Coordination Sphere ◽  
Olefin Metathesis ◽  
Ring Closing Metathesis ◽  
Axially Chiral ◽  
Half Sandwich

A remarkable helical complex with a chelating Cp-NHC ligand has been synthesised via olefin metathesis in the Ni(ii) coordination sphere.

scholarly journals New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-binaphthyl

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1165
Author(s):  
Yasuhiro Sato ◽  
Yuichi Kawata ◽  
Shungo Yasui ◽  
Yoshihito Kayaki ◽  
Takao Ikariya
Keyword(s):  
Hydrogen Transfer ◽  
Bond Cleavage ◽  
Enantiomeric Excess ◽  
Transfer Hydrogenation ◽  
Catalyst Precursor ◽  
Asymmetric Catalysts ◽  
Axially Chiral ◽  
Diastereomeric Mixture ◽  
Raney Ni ◽  
Half Sandwich

As a candidate for bifunctional asymmetric catalysts containing a half-sandwich C–N chelating Ir(III) framework (azairidacycle), a dinuclear Ir complex with an axially chiral linkage is newly designed. An expedient synthesis of chiral 2,2′-bis(aminomethyl)-1,1′-binaphthyl (1) from 1,1-bi-2-naphthol (BINOL) was accomplished by a three-step process involving nickel-catalyzed cyanation and subsequent reduction with Raney-Ni and KBH4. The reaction of (S)-1 with an equimolar amount of [IrCl2Cp*]2 (Cp* = η5–C5(CH3)5) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (5) through the double C–H bond cleavage, as confirmed by 1H NMR spectroscopy. A loss of the central chirality on the Ir centers of 5 was demonstrated by treatment with KOC(CH3)3 to generate the corresponding 16e amidoiridium complex 6. The following hydrogen transfer from 2-propanol to 6 provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium 5 can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a catalyst ratio of 200 in the presence of KOC(CH3)3 in 2-propanol, leading to (S)-1-phenylethanol with up to an enantiomeric excess (ee) of 67%.

New pseudohalide ligands in Ru-catalyzed olefin metathesis — A robust, air-activated iminopyrrolato catalyst

2005 ◽  
Vol 83 (6-7) ◽  
pp. 748-754 ◽  
Author(s):  
Samantha D Drouin ◽  
Heather M Foucault ◽  
Glenn PA Yap ◽  
Deryn E Fogg
Keyword(s):  
Key Words ◽  
Olefin Metathesis ◽  
High Reactivity ◽  
Ring Closing Metathesis ◽  
Grubbs Catalyst ◽  
X Ray ◽  
X Ray Crystallography

Reaction of the Grubbs catalyst RuCl2(PCy3)2(CHPh) (1) with lithium 2-[(2,6-diisopropylphenyl)imino]pyrrolide·Et2O (LiNN′·Et2O) gives alkylidene complex 5, containing a chelating, σ-bound iminopyrrolato unit. The structure of 5 is confirmed by X-ray crystallography. Treatment of 5 with pyridine generates RuCl(NN′)(py)2(CHPh) (6) via displacement of PCy3. Complex 5 effects ring-closing metathesis in air, displaying high reactivity relative to 6.Key words: ruthenium, alkylidene, metathesis, pyrrolimine, iminopyrrolato.

scholarly journals Recent Advances in the Application of Ring-Closing Metathesis for the Synthesis of Unsaturated Nitrogen Heterocycles

Synthesis ◽  
2019 ◽  
Vol 51 (05) ◽  
pp. 1100-1114 ◽  
Author(s):  
Emilia Groso ◽  
Corinna Schindler
Keyword(s):  
Olefin Metathesis ◽  
Nitrogen Heterocycles ◽  
Short Review ◽  
Catalyst Design ◽  
Carbene Ligands ◽  
Ring Closing Metathesis ◽  
Recent Advances ◽  
Metathesis Reactions

This short review summarizes recent advances relating to the application of ring-closing olefin-olefin and carbonyl-olefin metathesis reactions towards the synthesis of unsaturated five- and six-membered nitrogen heterocycles. These developments include catalyst modifications and reaction designs that will enable access to more complex nitrogen heterocycles.1 Introduction2 Expansion of Ring-Closing Metathesis Methods3 Evaluation of Catalyst Design4 Indenylidene Catalysts5 Unsymmetrical N-Heterocyclic Carbene Ligands6 Carbonyl-Olefin Metathesis7 Conclusions

scholarly journals Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

2018 ◽  
Vol 14 ◽  
pp. 2991-2998 ◽  
Author(s):  
Christiane Schultze ◽  
Bernd Schmidt
Keyword(s):  
Double Bond ◽  
Olefin Metathesis ◽  
Claisen Rearrangement ◽  
Allylic Oxidation ◽  
Allyl Ether ◽  
Ring Closing Metathesis ◽  
Wittig Olefination

8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination/cyclization sequence. They serve as a versatile platform for the annellation of five- to seven-membered rings using ring-closing olefin metathesis (RCM). Furano-, pyrano-, oxepino- and azepinocoumarins were synthesized from the same set of precursors using Ru-catalyzed double bond isomerizations and RCM in a defined order. One class of products, pyrano[2,3-f]chromene-2,8-diones, were inaccessible through direct RCM of an acrylate, but became available from the analogous allyl ether via an assisted tandem catalytic RCM/allylic oxidation sequence.

Template-Directed Synthesis of Macroheterocycles by Ring-Closing Metathesis of Olefin-Substituted Pyridines in the Coordination Sphere of a Triplatinum Complex.

ChemInform ◽  
2003 ◽  
Vol 34 (44) ◽  
Author(s):  
A. V. Chuchuryukin ◽  
H. P. Dijkstra ◽  
B. M. J. M. Suijkerbuijk ◽  
R. J. M. Klein Gebbink ◽  
G. P. M. van Klink ◽  
...  
Keyword(s):  
Coordination Sphere ◽  
Ring Closing Metathesis ◽  
Directed Synthesis ◽  
Substituted Pyridines

scholarly journals New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

2010 ◽  
Vol 6 ◽  
pp. 1159-1166 ◽  
Author(s):  
Etienne Borré ◽  
Frederic Caijo ◽  
Christophe Crévisy ◽  
Marc Mauduit
Keyword(s):  
Olefin Metathesis ◽  
Kinetic Studies ◽  
Ring Closing Metathesis ◽  
Good Tolerance ◽  
Cross Metathesis ◽  
Activity Enhancement ◽  
Selection Of

Seven novel Hoveyda–Grubbs precatalysts bearing an aminosulfonyl function are reported. Kinetic studies indicate an activity enhancement compared to Hoveyda’s precatalyst. A selection of these catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemical functions.

scholarly journals Nitro-Grela-type complexes containing iodides – robust and selective catalysts for olefin metathesis under challenging conditions

2015 ◽  
Vol 11 ◽  
pp. 1823-1832 ◽  
Author(s):  
Andrzej Tracz ◽  
Mateusz Matczak ◽  
Katarzyna Urbaniak ◽  
Krzysztof Skowerski
Keyword(s):  
Steric Hindrance ◽  
Olefin Metathesis ◽  
Catalyst Stability ◽  
Ring Closing Metathesis ◽  
Cross Metathesis ◽  
Protic Solvents

Iodide-containing nitro-Grela-type catalysts have been synthesized and applied to ring closing metathesis (RCM) and cross metathesis (CM) reactions. These new catalysts have exhibited improved efficiency in the transformation of sterically, non-demanding alkenes. Additional steric hindrance in the vicinity of ruthenium related to the presence of iodides ensures enhanced catalyst stability. The benefits are most apparent under challenging conditions, such as very low reaction concentrations, protic solvents or with the occurrence of impurities.

Allyl sulphides in olefin metathesis: catalyst considerations and traceless promotion of ring-closing metathesis

2015 ◽  
Vol 51 (3) ◽  
pp. 515-518 ◽  
Author(s):  
Grant A. Edwards ◽  
Phillip A. Culp ◽  
Justin M. Chalker
Keyword(s):  
Olefin Metathesis ◽  
Ring Closing Metathesis ◽  
Metathesis Catalyst

Allyl sulphides provoke rapid olefin metathesis when matched with an appropriate catalyst. In relay metathesis, allyl sulphides can serve as traceless promoters that facilitate the synthesis of non-sulphide targets.

scholarly journals Olefin metathesis in nano-sized systems

2011 ◽  
Vol 7 ◽  
pp. 94-103 ◽  
Author(s):  
Didier Astruc ◽  
Abdou K Diallo ◽  
Sylvain Gatard ◽  
Liyuan Liang ◽  
Cátia Ornelas ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Covalent Attachment ◽  
Enyne Metathesis ◽  
Ring Closing Metathesis ◽  
Cross Metathesis ◽  
Metathesis Reactions ◽  
Nano Catalysts

The interplay between olefin metathesis and dendrimers and other nano systems is addressed in this mini review mostly based on the authors’ own contributions over the last decade. Two subjects are presented and discussed: (i) The catalysis of olefin metathesis by dendritic nano-catalysts via either covalent attachment (ROMP) or, more usefully, dendrimer encapsulation – ring closing metathesis (RCM), cross metathesis (CM), enyne metathesis reactions (EYM) – for reactions in water without a co-solvent and (ii) construction and functionalization of dendrimers by CM reactions.

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