Sequential olefin metathesis — Intramolecular asymmetric Heck reactions in the synthesis of polycycles

2004 ◽  
Vol 82 (2) ◽  
pp. 399-407 ◽  
Author(s):  
Mark Lautens ◽  
Valentin Zunic
Keyword(s):  
Double Bond ◽  
Heck Reaction ◽  
Olefin Metathesis ◽  
Heck Reactions ◽  
Ring Closing Metathesis ◽  
Double Bond Migration ◽  
Double Ring ◽  
Asymmetric Heck Reaction

Application of the intramolecular asymmetric Heck reaction in the desymmetrization of a novel class of symmetrical bicyclodienes, synthesized through a diastereoselective double ring-closing metathesis (DSRCM) reaction, was achieved with good yields (approximately 80%) and excellent enantioselectivities (up to 99% ee). Three contiguous stereocenters are established in a single desymmetrization reaction. The use of thallium carbonate as base in the asymmetric Heck reaction favours double bond migration in 13. Cationic conditions delivered products with good to excellent enantioselectivities, surpassing the results under neutral conditions.Key words: asymmetric, Heck, polycycles, metathesis, stereoselective, desymmetrization.

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.

Chiron approach for the total synthesis of brevipolide M

Synlett ◽  
2022 ◽  
Author(s):  
Yang Liu ◽  
Ziyang Zhao ◽  
Chao Hu ◽  
Chuanfang Zhao ◽  
Jun Liu ◽  
...  
Keyword(s):  
Double Bond ◽  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Ring Closing Metathesis ◽  
One Pot ◽  
Double Bond Migration ◽  
Key Steps

An efficient stereoselective synthesis of brevipolide M was established in 13 linear steps and 17.8% overall yields base on chiron approach. The key steps of our synthesis involved tandem homologation / tetrahydrofuran cyclization and sequential ring-closing metathesis (RCM) / double-bond migration in one-pot processes.

scholarly journals Synthesis of Dihydropyrano[3,2-c]pyrazoles via Double Bond Migration and Ring-Closing Metathesis

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 296 ◽  
Author(s):  
Yoshihide Usami ◽  
Kodai Sumimoto ◽  
Azusa Kishima ◽  
Yuya Tatsui ◽  
Hiroki Yoneyama ◽  
...  
Keyword(s):  
Double Bond ◽  
Claisen Rearrangement ◽  
Ring Closing Metathesis ◽  
Double Bond Migration ◽  
Ruthenium Hydride

Three types of pyrazole-fused heterobicycles, i.e., 1,5-, 1,7-, and 2,5-dihydropyrano[3,2-c]pyrazoles, were synthesized from 4-allyloxy-1H-pyrazoles. A sequence of the Claisen rearrangement of 4-allyloxy-1H-pyrazoles, ruthenium-hydride-catalyzed double bond migration, O-allylation, and ring-closing metathesis was employed in this study.

Construction of Benzylic Stereogenic Carbon Centers through Enantioselective Arylation Reactions

Synlett ◽  
2017 ◽  
Vol 29 (02) ◽  
pp. 157-168 ◽  
Author(s):  
Ren-Rong Liu ◽  
Ren-Xiao Liang ◽  
Yi-Xia Jia
Keyword(s):  
Natural Products ◽  
Heck Reaction ◽  
Alkylation Reaction ◽  
Heck Reactions ◽  
Carbon Centers ◽  
Drug Molecules ◽  
Stereogenic Centers ◽  
Asymmetric Heck Reaction ◽  
Alkylation Reactions

Compounds bearing chiral benzylic stereocenters are important and frequently occur in natural products and drug molecules. In this account, we discuss our recent results on the construction of ­benzylic stereogenic centers based on enantioselective arylation and related domino sequences, mainly including asymmetric Friedel–Crafts alkylation reactions and asymmetric Heck reactions.1 Introduction2 The Catalytic Asymmetric Friedel–Crafts Alkylation Reaction2.1 Reactions of Electron-Deficient Alkenes2.2 Reactions of Active Ketimines2.3 Reactions of Nitrones2.4 Reactions of Aziridines3 The Asymmetric Heck Reaction3.1 Dearomative Heck Reactions and Related Domino Sequences3.2 Heck Reactions of in situ Formed Enamines4 Conclusion and Outlook

scholarly journals Transformations of terpenes and terpenoids via carbon–carbon double bond metathesis

2018 ◽  
Vol 8 (16) ◽  
pp. 3989-4004 ◽  
Author(s):  
Christian Bruneau ◽  
Cédric Fischmeister ◽  
Dalmo Mandelli ◽  
Wagner A. Carvalho ◽  
Eduardo N. dos Santos ◽  
...  
Keyword(s):  
Double Bond ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Ring Closing Metathesis ◽  
Cross Metathesis ◽  
Carbon Double Bond ◽  
Review Reports

The review reports on transformations of unsaturated terpenes and terpenoids via olefin metathesis processes including ring closing metathesis of dienes, cross metathesis with functional olefins and ethenolysis, and ring opening metathesis as well as ring opening/cross metathesis.

Connecting catalytic cycles by organometallic transformations in situ: Novel perspectives in the olefin metathesis field

2006 ◽  
Vol 78 (2) ◽  
pp. 469-476 ◽  
Author(s):  
Bernd Schmidt
Keyword(s):  
Double Bond ◽  
Olefin Metathesis ◽  
Metathesis Reaction ◽  
Ring Closing Metathesis ◽  
Double Bond Isomerization ◽  
Metathesis Catalyst ◽  
Organometallic Transformations ◽  
Catalytic Cycles

Tandem sequences consisting of an olefin metathesis step and a subsequent non-metathesis reaction become accessible by organometallic transformations of the Ru-carbene species in situ. This contribution highlights some tandem sequences that rely on the conversion of the metathesis catalyst to Ru-hydrides, with special emphasis on the tandem ring-closing metathesis (RCM)-double-bond isomerization sequence.

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.

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