Enantiocontrolled Azetidine Library Synthesis via Strain-Release Functionalization of 1-Azabicyclobutanes.

A simple, modular, and programmable approach to access complex stereopure azetidines through strain-release functionalization is disclosed. The synthetic methods developed enable the parallel synthesis of stereodefined azetidines that would be otherwise laborious to produce. Given the privileged nature of these structures, a set of stereoprobes for use in activity-based protein profiling was prepared and evaluated, revealing proteins in human cancer cells, which were liganded with clear stereo- and chemo-selectivity.