Anion-accelerated asymmetric Nazarov cyclization: access to vicinal all-carbon quaternary stereocenters.

We have developed a catalytic asymmetric Nazarov cyclization that results in the formation of two contiguous all-carbon quaternary stereocenters in high yield with excellent levels of asymmetric induction. This method requires no catalyst recognition elements in the starting materials that are simple diketoesters. Geometrically pure or isomers of the starting material lead to diastereomerically pure products with high enantioselectivity because the species that undergoes cyclization is a rhodium enolate that is configurationally stable.