Probe of the Stereochemically Determining Step in Squarate Ester Cascades. Proof that Helical Equilibration within the Octatetraene Intermediate Is Responsible and Definition of Steric Control Elements

摘要

The stereoselectivity associated with the coaddition of a chiral and an achiral cycloalkenyl anion to a squarate ester has been examined. The selective formation of polycyclic ketones is observed in all cases. although dual protonation at both of the available enolate sites in their penultimate cyclooctatrienyl dianion precursors was sometimes noted.