The formation of cycloheptenone and cycloheptadienones from bicyclo[3.2.0]heptanone derivatives. An acid-catalyzed, two carbon ring expansion reaction
- 1 January 1976
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 54 (1) , 12-18
- https://doi.org/10.1139/v76-004
Abstract
In strong acids, such as FSO3H and 96% H2SO4, bicyclo[3.2.0]heptan-6-one and bicyclo[3.2.0]hept-2-en-7-one undergo a clean isomerization to form protonated cyclohept-2-enone and cyclohepta-2,4-dienone, respectively. Substituted derivatives undergo comparable ring expansions when dissolved in these strong acids. The seven-membered ring ketones can be recovered on quenching the acid solutions with a NaHCO3–ether mixture. In contrast, bicyclo[3.2.0]hept-2-en-6-one when dissolved in FSO3H rearranged to give protonated 1-acetylcyclopentadiene. The mechanism and synthetic utility of these reactions is discussed.Keywords
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