Selectivity Control in Lewis Acid Catalyzed Regiodivergent Tandem Cationic Cyclization/Ring Expansion Terminated by Pinacol Rearrangement

2009 ◽  
Vol 121 (33) ◽  
pp. 6209-6212 ◽  
Author(s):  
Lu Liu ◽  
Junliang Zhang
Keyword(s):  
Lewis Acid ◽  
Ring Expansion ◽  
Pinacol Rearrangement ◽  
Acid Catalyzed ◽  
Cationic Cyclization ◽  
Selectivity Control

Internal Lewis acid catalyzed ring-expansion reactions of cyclopropylalkanoyl chlorides

1975 ◽  
Vol 16 (35) ◽  
pp. 3031-3034 ◽  
Author(s):  
Michael P. Doyle ◽  
Thomas R. Bade
Keyword(s):  
Lewis Acid ◽  
Ring Expansion ◽  
Acid Catalyzed

Lewis Acid-Catalyzed Stereospecific Ring Expansion of Aziridine-2-carboxylates to Imidazolidin-2-ones.

ChemInform ◽  
2005 ◽  
Vol 36 (43) ◽  
Author(s):  
Min Sung Kim ◽  
Yong-Woo Kim ◽  
Heung Sik Hahm ◽  
Jae Won Jang ◽  
Won Koo Lee ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Ring Expansion ◽  
Acid Catalyzed

scholarly journals Ring-fused cyclobutanes via cycloisomerization of alkylidenecyclopropane acylsilanes

2020 ◽  
Vol 11 (20) ◽  
pp. 5294-5298
Author(s):  
Sarah Eichenberger ◽  
Moritz Hönig ◽  
Matthieu J. R. Richter ◽  
Renana Gershoni-Poranne ◽  
Erick M. Carreira
Keyword(s):  
Lewis Acid ◽  
Ring Expansion ◽  
Acid Catalyzed

A novel Lewis acid-catalyzed cycloisomerization of alkylidenecyclopropane acylsilanes is disclosed that involves tandem Prins addition/ring expansion/1,2-silyl shift to grant access to bicyclo[4.2.0]octanes and bicyclo[3.2.0]heptanes.

Synthesis and Lewis acid induced isomerization of mono-, di-, and tri-spiro α-keto tetrahydro-furans and -pyrans

2006 ◽  
Vol 84 (10) ◽  
pp. 1388-1396 ◽  
Author(s):  
David G Hilmey ◽  
Peter R Selvaraj ◽  
Leo A Paquette
Keyword(s):  
Lewis Acid ◽  
Ground State ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Ring Expansion ◽  
Stage Conversion ◽  
Ring Expansions ◽  
Third Stage ◽  
Synthetic Equivalent ◽  
Acid Catalyzed

The stereoselectivity of the acid-catalyzed ring expansion of dihydrofuranyl and dihydropyranyl 1,2-adducts to spirocyclic ketones 8 and 9 has been examined. These substrates have become readily available by the utilization of 1,3-dichloroacetone as a synthetic equivalent of cyclopropanone. The kinetically controlled isomerizations result in ring expansion to dispirocyclopentanones. Third-stage conversion to trispirocyclohexanones was shown to be possible in select examples. On a different front, the syn and anti pairs proved capable of interconversion by heating in the presence of boron trifluoride etherate. A push–pull fragmentation of the ketone ring is proposed to account for these epimerizations. Calculations have been performed to simulate transition state energies in the oxonium ion intermediates and to gain some idea of the preferred ground-state geometries of the final products.Key words: oxonium ion rearrangements, ring expansions, acid-catalyzed epimerizations, cyclopropanone equivalent, spirocyclic ethers.

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