128856-03-1Relevant articles and documents
Zirconocene-catalyzed cationic Diels-Alder reactions
Wipf, Peter,Xu, Wenjing
, p. 4551 - 4562 (2007/10/02)
In situ prepared Cp2ZrCl+ catalyzes the formation of dioxolenium ions from α,β-unsaturated epoxy esters. As a consequence of this activation process, acrylate, methacrylate and crotonate derivatives undergo a rapid and stereoselective cationic [4+2] cycloaddition with a wide range of dienes. Ring-extended carboxylic acid derivatives are formed in 1-7 h at 0-21°C and in 50-90% yield after saponification of the intermediate diol esters. Simple Lewis acid catalysis by Cp2ZrCl+ can be excluded on the basis of the experimental results.