Solvent effects in the Cope rearrangement

1970 ◽  
Vol 48 (5) ◽  
pp. 855-858 ◽  
Author(s):  
Donald C. Wigfield ◽  
Steve Feiner
Keyword(s):  
Solvent Effects ◽  
Cope Rearrangement ◽  
Ionic Mechanism ◽  
Cope Rearrangements ◽  
Negligible Contribution

Mechanistic ambiguity in the kinetic results of certain Cope rearrangements has been resolved. It is concluded from rate studies in solvents of widely differing polarity that there is negligible contribution of an ionic mechanism, even in rearrangements of substrates structurally best suited to this mechanism.

Aromatic Cope Rearrangements

2021 ◽  
Author(s):  
Breanna Tomiczek ◽  
Alexander Grenning
Keyword(s):  
Cope Rearrangement ◽  
Aromatic System ◽  
Cope Rearrangements

Reviewed herein is the aromatic Cope rearrangement, a Cope rearrangement where one (or both) of the alkenes of the 1,5-diene are part of a greater aromatic system. While the Cope...

A Caveat Concerning Anionic Oxy-cope Rearrangements Within Bicyclo[2.2.2]octenyl Frameworks

1996 ◽  
Vol 49 (5) ◽  
pp. 639 ◽  
Author(s):  
MG Banwell ◽  
JR Dupuche ◽  
RW Gable
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Cope Rearrangement ◽  
Diels Alder Reaction ◽  
Cope Rearrangements ◽  
Potassium Hydride

Compounds (10), (15) and (16) all react with potassium hydride at 0°C to give, via retro- Diels-Alder reaction, 1-methylnaphthalene (12) in 60-67% yield. No evidence could be obtained for the formation of a product derived from the anionic oxy-Cope rearrangement of substrate (16).

Part 2: Efficient strategies for the construction of variably substituted bicyclo[5.3.1]undecenones (AB-taxane ring systems) and their conversion to tricyclo[9.3.1.03,8]pentadecenones (ABC taxane ring systems) and bicyclo[2.2.2]octanones

2004 ◽  
Vol 82 (2) ◽  
pp. 227-239 ◽  
Author(s):  
Nidia P Villalva-Servín ◽  
Alain Laurent ◽  
Alex G Fallis
Keyword(s):  
Lewis Acid ◽  
Sigmatropic Rearrangement ◽  
Diels Alder ◽  
Direct Access ◽  
Cope Rearrangement ◽  
Ring Closing Metathesis ◽  
Ring Systems ◽  
Sigmatropic Rearrangements ◽  
Key Words Magnesium ◽  
Cope Rearrangements

The extension of our strategies for the construction of cyclic molecules containing variably substituted bicyclo[5.3.1]undecenones (AB taxane ring systems) for the synthesis of the tricyclo[9.3.1.03,8]pentadecenone (ABC taxane ring system) and bicyclo[2.2.2]octanones are described. These routes employ a multi-component coupling protocol that employs sequential magnesium-mediated carbometallation of allyl-substituted propargyl alcohols followed by diastereoselective Lewis acid catalyzed intramolecular Diels–Alder reactions (IMDA). Subsequent ring-closing metathesis (RCM) afforded the ABC taxane core structure. Enone accelerated [3,3] sigmatropic rearrangements (Cope rearrangements) generated the bicyclo[2.2.2]octanone nucleus. In the presence of a Lewis acid, the dienophile precursor underwent a tandem reaction via the adduct directly to the bicyclo[2.2.2]octanones. This is the first example of a novel enone accelerated carbocycle Cope rearrangement and provides direct access to bicyclo[2.2.2]octanones by a new route that compliments the traditional cyclohexadiene cycloaddition approach. Key words: magnesium chelate, Lewis acid, taxanes, Diels–Alder, sigmatropic rearrangement, oxy-Cope, ring-closing metathesis, bicyclo[2.2.2]octanone.

scholarly journals Diastereoselective Indole-Dearomative Cope Rearrangements by Compounding Minor Driving Forces.

2022 ◽  
Author(s):  
Subhadip De ◽  
Breanna Tomiczek ◽  
Yinuo Yang ◽  
Kenneth Ko ◽  
Ion Ghivirga ◽  
...  
Keyword(s):  
Functional Groups ◽  
Driving Forces ◽  
Starting Material ◽  
Cope Rearrangement ◽  
Proof Of Concept ◽  
Complex Architectures ◽  
Cope Rearrangements ◽  
High Yields

Reported herein is the discovery of a diastereoselective indole-dearomative Cope rearrangement. A suite of minor driving forces (substrate destabilizing effects; product stabilizing effects) are what promote this otherwise unfavorable dearomatization reaction. These include the following that work in concert to overcome the penalty for dearomatization: (i.) steric congestion in the starting material, (ii.) alkylidene malononitrile and stilbene conjugation events in the product, and (iii.) an unexpected intramolecular p–p* stack on the product side of the equilibrium. The key substrates are rapidly assembled from alkylidenemalononitriles and indole-phenylmethanol derivatives resulting in many successful examples (high yields and diastereoselectivity). The products are structurally complex bearing vicinal stereocenters generated by the dearomative Cope rearrangement. They also contain a variety of functional groups for interconversion to complex architectures. On this line, also described herein are proof-of-concept strategies for achieving enantioselectivity and conversion of the dearomative products to valuable and functionalized small drug-like molecules.

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