Synthetic and mechanistic studies of the retro-Claisen rearrangement: an example of cation acceleration of a [3,3]-sigmatropic rearrangement

1985 ◽  
Vol 107 (14) ◽  
pp. 4359-4362 ◽  
Author(s):  
Robert K. Boeckman ◽  
Christopher J. Flann ◽  
Kathleen M. Poss
Keyword(s):  
Claisen Rearrangement ◽  
Sigmatropic Rearrangement ◽  
Mechanistic Studies

scholarly journals Intermolecular 3+3 Ring Expansion of Aziridines to Dehydropiperidines through the Intermediacy of Aziridinium Ylides

2019 ◽  
Author(s):  
Jennifer Schomaker ◽  
Josephine Eshon ◽  
Kate A. Nicastri ◽  
Steven C. Schmid ◽  
William T. Raskopf ◽  
...  
Keyword(s):  
Natural Product ◽  
Functional Group ◽  
Ring Expansion ◽  
Sigmatropic Rearrangement ◽  
Reactive Intermediate ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Complex Molecules ◽  
Form Complex ◽  
Reaction Proceeds

Bicyclic aziridines undergo formal [3+3] ring expansion reactions when exposed to rhodium-bound vinyl carbenes to form complex dehydropiperidines in a highly stereocontrolled rearrangement. Mechanistic studies and DFT computations indicate the reaction proceeds through the formation of a vinyl aziridinium ylide; this reactive intermediate undergoes a concerted, asynchronous, pseudo-[1,4]- sigmatropic rearrangement to directly furnish the heterocyclic products with net retention at the new C-C bond. In combination with an asymmetric silver-catalyzed aziridination developed in our group, this method quickly delivers enantioenriched scaffolds with up to three contiguous stereocenters. The mild reaction conditions, functional group tolerance, and high stereochemical retention of this method are especially well-suited for appending piperidine motifs to natural product and complex molecules. Ultimately, our work establishes the value of underutilized aziridinium ylides as key intermediates in strategies to convert small, strained rings to larger N-heterocycles.

A Formal Metal-Free γ-Arylation of 1,3-Dicarbonyl Compounds via a Sequence of Isomerization/1,4-Addition/[3,3]-Sigmatropic Rearrangement

2021 ◽  
Author(s):  
Shi-Chao Lu ◽  
Fuqiang Wen ◽  
Xidong Guan
Keyword(s):  
Sigmatropic Rearrangement ◽  
Mechanistic Studies ◽  
Dicarbonyl Compounds ◽  
Metal Free

A metal-free redox arylation of alkynes with sulfoxides has been developed to provide an unconventional access to diverse γ-arylated 1,3-dicarbonyl compounds in an atom-economical manner. Mechanistic studies suggest that a...

Sequential O-Arylation/Lanthanide(III)-Catalyzed [3,3]-Sigmatropic Rearrangement of Bromo-Substituted Allylic Alcohols

Synlett ◽  
2017 ◽  
Vol 28 (20) ◽  
pp. 2865-2870 ◽  
Author(s):  
Timothy Ramadhar ◽  
Jun-ichi Kawakami ◽  
Robert Batey
Keyword(s):  
Claisen Rearrangement ◽  
Cross Coupling ◽  
Sigmatropic Rearrangement ◽  
Mitsunobu Reaction ◽  
Allylic Alcohols ◽  
Aryl Ether ◽  
Claisen Rearrangements ◽  
Snar Reaction ◽  
Aryl Ethers

Lanthanide(III)-catalyzed aryl-Claisen rearrangement of substrates bearing halo-substituted allyl groups, specifically 2-bromoallyl aryl ethers, afford ortho-2-bromoallylphenols. Aryl ether substrates were synthesized from brominated allylic alcohols via Mitsunobu reaction, Cu(II)-catalyzed arylation using potassium aryltrifluoroborate salts, or SNAr reaction. Aryl-Claisen rearrangements proceeded in moderate to excellent yields using Eu(III) catalysis. The alkenylbromide functionality remains intact, illustrating the compatibility of synthetically important alkenylhalides during C–O/C–C σ-bond migration processes. Subsequent derivatization of the ortho-2-bromoallylphenol products through O-alkylation or C-arylation/alkenylation via Suzuki–Miyaura cross-coupling demonstrate the potential to access densely-functionalized molecules.

Sign in / Sign up

Export Citation Format

Share Document