Water Freezing as a Regiocontrol Element in the Multicomponent Assembly of Cyclic Enones
作者:Raquel De la Campa、Josefa Flórez
DOI:10.1002/chem.201404670
日期:2015.1.26
Regioselective synthesis of dialkoxy 2‐cyclopentenones and 2‐cyclohexenones with novel substitution patterns has been accomplished by the one‐pot combination of three simple starting materials (chromium carbene complex, Weinreb acetamide lithium enolate and 1‐alkoxyallenyllithium) under either anhydrous conditions or water‐promoted solidification of the reaction mixture. These results revealed an unprecedented
Palladium-Catalyzed Diastereo- and Enantioselective Wagner−Meerwein Shift: Control of Absolute Stereochemistry in the C−C Bond Migration Event
作者:Barry M. Trost、Jia Xie
DOI:10.1021/ja7111299
日期:2008.5.1
Inducing absolute stereochemistry in Wagner-Meerwein shifts was examined in a ring expansion protocol. Initiated by generation of a pi-allylpalladium intermediate by hydropalladation of allenes, the ring expansion of allenylcyclobutanol substrates proceeded with excellent diastereo- and enantioselectivities. The results demonstrate that, during the C-C bond migration process, our chiral catalysts can control the stereochemistry of both the pi-allylpalladium intermediate and the corresponding migration bond. Moreover, the stereochemical outcome of the reaction can be rationalized very well with the working model of the chiral catalyst. The method provides an efficient way to synthesize highly substituted cyclopentanones with an alpha-chiral O-tertiary center which has various synthetic applications.