The stereochemical outcome of the conjugate addition of organocopper reagents to bicyclic α,β-unsaturated lactams derived from pyroglutaminol is determined by the nature of the aminal group, whether it is derived from an aldehyde or ketone. Aminals derived from aldehydes lead to anti addition of the cuprate, while aminals derived from ketones lead to syn addition products. The mechanistic basis for this divergence in diastereoselection arises because the reactions occur via different mechanisms due to fundamental differences in the redox potentials of the two olefins, which in turn are ultimately modulated by small but clearly significant differences in the pyramidalization of the aminal nitrogen. This is a very clear example of a seemingly minor change to a reactant leading to large and unintended outcomes in reactivity.

Small change, big impact: Reversal of diastereoselection in cuprate conjugate additions to α,β-unsaturated lactams and identification of a new mechanism

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.