Trost BM, * Morris PJ, Sprague SJ. Stanford University, USA
Palladium-Catalyzed Diastereo- and Enantioselective Formal [3 + 2]-Cycloadditions
of Substituted Vinylcyclopropanes.
J. Am. Chem. Soc. 2012;
134: 17823-17831
Key words
palladium - Trost ligand - vinylcyclopropanes - formal [3+2] cycloaddition - cyclopentanes
Significance
A palladium-catalyzed asymmetric formal [3+2] cycloaddition of vinylcyclopropanes
to electron-poor olefins is reported using the Trost ligand. The developed method
can access highly substituted cyclopentanes with high diastereo- and enantioselectivity
with moderate to high yield.
Comment
As the vinylcyclopropanes 1 used are racemic, the authors propose that the reaction occurs under Curtin–Hammett
conditions for this stereo-convergent reaction. Notably, the effects of π–σ– π interconversion
and the reversibility of the conjugate addition establish pre-equilibria of diastereomeric
reactive intermediates 4 and 5, consequently favoring the formation of 3.
