Ring-size manipulation has emerged as a powerful strategy to convert readily available cyclic structures into ringexpanded or ring-contracted compounds that are more difficult to synthesize using conventional means. In particular, "cut and sew" strategies relying on transition-metal catalyzed oxidative addition across C-C bonds are useful approaches for insertion of carbon monoxide or two-carbon fragments such as olefins and alkynes to effect one-or twocarbon ring expansions, respectively. For nitrogen-containing heterocycles, one possible strategy for ring expansion is to induce a [1,2]-Stevens rearrangement by formation of an ammonium ylide, resulting in one-carbon ring expansion. Pioneering works by Hata, West, and Couty demonstrated this approach for 4-to 5-membered ring expansions, wherein treatment of an azetidine with a diazo compound in the presence of a copper catalyst provided facile access to the corresponding pyrrolidine. Conceptually, carbene transfer followed by an intramolecular [1,2]-Stevens rearrangement complements "cut and sew" reactions for non-carbonylative, one-carbon homologation of nitrogen-containing compounds. Given the prevalence of nitrogen heterocycles across numerous sectors of the chemical industry, especially pharmaceuticals, extending these methodologies to other saturated N-heterocycles would represent a new approach for the synthesis of important chiral amine building blocks.