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Interception of Nazarov Reactions of Allenyl Vinyl Ketones with Dienes: (3+2)‐ versus (4+3)‐Cycloaddition and Subsequent Rearrangement
Author(s) -
Morgan Timothy D. R.,
LeFort François M.,
Li Zhe,
Marx Vanessa M.,
Boyd Russell J.,
Burnell D. Jean
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201403618
Subject(s) - cycloaddition , chemistry , steric effects , ring (chemistry) , diene , medicinal chemistry , molecule , decomposition , transition state , stereochemistry , organic chemistry , catalysis , natural rubber
Capture of the cyclic oxyallyl cation intermediates from the BF 3 ‐mediated Nazarov reactions of three allenyl vinyl ketones with various dienes was accomplished by (3+2)‐ and (4+3)‐cycloaddition. The relative amounts of these types of products were dependent on the substitution on the diene, and this could be linked to steric hindrance. Treatment of the (3+2)‐cycloaddition products with BF 3 · Et 2 O led mainly to decomposition but also to ring‐opened molecules and ring‐enlarged structures. The computed Gibbs energies of the (3+2)‐cycloaddition products, the products of the acid treatment and of some transition states leading to rearranged products were compared.