Nazarov reaction of trisubstituted dienones: mechanism involving Wagner-Meerwein shift
摘要:
The Nazarov reactions of trisubstituted alpha,alpha'-dienones were studied. Whereas alpha,beta-dimethyl-beta'-alkyl alpha,alpha'-dienones gave 2,3-dimethyl-4-alkyl-2-cyclopentenones when heated in concentrated sulfuric acid, the reaction of beta,beta-dimethyl-beta'-alkyl alpha,alpha'-dienones afforded 3,4-dimethyl-4-alkyl-2-cyclopentenones as the rearranged products. A mechanistic investigation using two deuterated dienones suggests that the Nazarov reactions of the latter dienones are accompanied by Wagner-Meerwein shifts to form the most stable carbocations.
Equilibria Studies on Tetraalkylcyclopentenyl Cations. A Steric Origin for a Baker–Nathan Order?
作者:K. Ranganayakulu、T. S. Sorensen
DOI:10.1139/v72-567
日期:1972.11.1
The possibilities of using observable cation equilibria to obtain evidence concerning C—H hyperconjugation are discussed. The experimental approach of this paper, using tetraalkylcyclopentenyl cation equilibria, is to vary the structure of the "normal" alkyl series in such a way that the hypothetical C—H hyperconjugative ability remains constant for a given series while the steric bulk of the groups