Having established optimal reaction conditions, we next investigated the scope of the photochemical C1 homologation of RAEs derived from readily available carboxylic acids (Figure ). As expected, N-Boc protected cyclic amino acids afforded the desired products (3-5) in good yields. Moreover, linear proteogenic amino acids underwent homologation to the respective ethyl esters (6-13) under the standardized reaction conditions. Noteworthy is the performance of challenging substrates, such as the redox-sensitive methionine and thiophene-derived amino acid, which, despite providing the target compounds (8 and 10), did so in somewhat attenuated yields. The protocol's generality was highlighted through the homologation of sterically hindered cyclic tertiary amino acids, producing the target products in synthetically useful yields (14-16). A subsequent examination of various inactivated primary, secondary, and tertiary RAEs revealed that all coupled with glyoxalate-derived sulfonyl hydrazones 2a, presenting moderate to good yields (17-22). In a particularly notable development, two dipeptides underwent photochemical homologation, yielding the targeted homoproline-analogues (23-24). Importantly, the mild conditions of this photocatalytic C1 homologation protocol facilitated the conversion of natural products like biotin and enoxolone-each harboring different sensitive functional groups-to their corresponding ethyl esters (25-26), not accessible by the aforementioned methods.