After having established this one-pot C(sp 3 )-H alkylation procedure, we questioned whether the instalment of an ester moiety would be feasible through use of an ethyl glyoxylate-derived sulfonyl hydrazone 1aj (Figure , 54-61). For the cleavage step, a solvent switch to ethanol proved to be essential to ensure reproducible results (see SI, section 5.2). Capitalizing on our two-step process, we discovered that various aliphatic ethers and amines could be readily coupled, delivering the corresponding products in good yields (54-61, 35-85%). Notably, our method provides also immediate access to various β-amino acids, common moieties in many marketed therapeutics (56-61, 35-76%). Next, we performed some experiments aimed at elucidating the mechanism of this photochemical alkylative process. The involvement of carbon-centered radicals was confirmed by the presence of adduct 62, obtained upon addition of TEMPO as radical scavenger (Figure ). The observed kinetic isotope effect (KIE) value of 2.5 indicates that HAT is most likely the rate determining step (Figure ). Quantum yield measurements revealed that the reaction is photocatalytic in nature and that a radical chain is either absent or inefficient (Φ = 0.45, see SI, section 9.4). From this experimental evidence, a plausible catalytic cycle can be derived as presented in Figure . Upon absorption of a 390 nm photon, the excited state of 4-Cl2-BP is responsible for the cleavage of the C(sp 3 )-H bond, thus generating the nucleophilic alkyl radical 63. This transient species can undergo a polarity-matched addition to the electrophilic site of 64, delivering a putative hydrazinyl radical 65. At this stage, a back-HAT event from the reduced form of 4-Cl2-BP to 65 is envisioned, yielding the Csp 3 -H alkylated product 66 and closing the photocatalytic cycle.