Tunable [3+2] and [4+2] annulations for pyrrolidine and piperidine synthesis.

N-heterocycles are privileged pharmaceutical scaffolds in drug discovery and development. We disclose here divergent intermolecular coupling strategies that can access diverse N-heterocycles directly from olefins. The radical-to-polar mechanistic switching is key for the divergent cyclization processes. These distinctive annulations result in the coupling of alkenes with simple bifunctional reagents for divergent N-heterocycle syntheses.

Visible light bromide catalysis for oxazoline, pyrrolidine, and dihydrooxazine syntheses via Csp3-H functionalizations.

A catalytic benzylic Csp3-H functionalization protocol is described here. This visible light-mediated process is centered on the utilization of a bromide catalyst and oxidant to generate a nitrogen (N)-centered radical for a site-selective hydrogen atom transfer (HAT) process. This strategy enabled the unconventional syntheses of a number of N-heterocycles dependent on the amide identity. We also discovered a nucleophilicity-dependent kinetic resolution for stereochemical differentiation of Csp3-H bonds that enabled the stereoselective synthesis of cis- and trans-oxazolines.