Synthesis and reactivity of dioxycarbenium ions from epoxy esters and cationic zirconium complexes
作者:Peter Wipf、Wenjing Xu
DOI:10.1021/jo00074a006
日期:1993.10
Rearrangement of epoxy esters in the presence Of Cp2Zr(R)+ or CP2Zr(Cl)+ results in synthetically useful dioxycarbenium intermediates. Acetals, ortho esters, and tetrahydrofurans are prepared by ligand transfer from zirconium, intramolecular trapping, or further rearrangement reactions.
Zirconocene-catalyzed epoxy ester - ortho ester rearrangement: A new method for the protection of polyfunctionalized carboxylic acids and the asymmetric synthesis of ortho esters
In situ prepared Cp2(Cl)Zr⊛ catalyzes the formation of ortho eśters from epoxy esters. Acid-sensitive α-amino and α-hydroxy acid derivatives are converted in high yield to 2,7,8-trioxabicyclo[3.2.1]octanes (ABO-esters) using this protocol. This strategy is complementary to the OBO-ester technology, and orthogonal methods for the deprotection of ABO- and OBO-esters have been developed. The syntheses