Ring strain in organic molecules is a powerful driving force that promotes reactivity through strain release, enabling the facile construction of a myriad of useful scaffolds via ring-opening or ring-expansion reactions. In the first part of this lecture, I will discuss a photoredox-catalyzed Dowd-Beckwith ring-expansion/radical-polar crossover (RPC) strategy for the synthesis of functionalized medium-sized carbocycles.1 Deconstructive approaches have recently emerged as valuable tools for molecular remodelling; however, the selective cleavage and functionalization of inert C−C bonds, particularly in unstrained cyclic systems, remain significant challenges. In the second part, I will present an RPC-interrupted Dowd-Beckwith reaction that enables efficient C−C bond cleavage and functionalization.2 Next, I will describe a strainenabled RPC platform for the unified synthesis of spiro-, fused-, and enantioenriched aza-/oxa-bicyclo[3.1.1]heptanes.3 Finally, I will conclude by presenting a practical approach that employs methylenecyclobutanes as starting materials for the efficient synthesis of enantioenriched aza-bicyclo[2.1.1]hexanes (aza-BCHs) via electrochemical haloamination using Ellman's sulfinamide chemistry.4