Next, we sought to examine the substrate scope of this reaction and whether or not the new selectivities we observed could be extended to other substrates. When this reaction was run at 0.5-mmol scale, azetidine 2 could be formed in 75% yield, 1490 TTN, 67% isolated yield, and 99:1 er. Other aromatic groups could be used in lieu of a phenyl group with uniformly high enantioselection observed in all cases. Notably, a thiophene-bearing aziridine could undergo chemoselective ring expansion to azetidine 3 with no observed cyclopropanation byproducts. This selectivity is notable not only because thiophenes are known to react with EDAderived metal carbenoids under mild conditions, but also because Parent F2 was originally engineered to perform cyclopropanation of heteroatom-substituted olefins. Fluorine substituents were also tolerated on the arene ring at the para, meta, and ortho positions to furnish fluorinated products 4-6. In addition to EDA, other diazoacetate compounds could participate in one-carbon ring expansion with at least 99:1 er (7-8). When methyl diazoacetate was used as the carbene precursor to yield 9, a notable decrease in er (81:19) was observed. One hypothesis for this decrease in enantiopurity is that the smaller aliphatic chain allows for greater conformational freedom of the iron porphyrin carbene intermediate or the putative diradical intermediate. This explanation is consistent with prior work on enzymemediated carbene transfer reactions using perfluoroalkylstabilized diazo compounds as carbene precursors, where the substrate chain length has a profound influence on the absolute stereochemical configuration of the reaction product. The reaction could also be scaled up from 0.5-mmol scale to 10-mmol scale to furnish 2 in 1220 TTN, 61% yield, and 99:1 er with an isolated yield of 1.44 g (55% isolated yield), demonstrating that gram-scale production of enantioenriched azetidines is viable using this platform and that extension of this activity could be a powerful tool for the asymmetric synthesis of chiral heterocycles.