Mechanism. As mentioned in the introduction, the photocatalytic generation of α-aminoalkyl radicals from cyclic anilines and their subsequent intermolecular addition to Michael acceptors are wellestablished processes. However, the selectivity of the reaction sequence responsible for the annulation process is quite unique and deserves to be discussed (Scheme 11). Upon blue light irradiation the catalyst Ir-A reaches its excited state Ir(III)*(Eox* Ir (III*/II) = +1.21 V SCE in MeCN) and is able to oxidize N-phenylpyrrolidine 1a to its aminium radical cation RC1a (Ered = +0.62 V/SCE in MeCN), which generates the α-aminoalkyl radical R1a upon deprotonation. This nucleophilic radical adds to the electron-poor double bond of the allylic trap, leading to an intermediate α-ester radical RE2a. The reduction potential of the tertiary radical RE2a is estimated to be Ered > -0.29 V SCE (see supporting information for details). Such a radical is expected to be readily reduced by the Ir(II) species (Ered Ir (III/II) = -1.37 V/SCE), thus closing the first catalytic cycle and providing a transient enolate intermediate that produces the mono-allylated pyrrolidine 2a upon β-fragmentation. The intermediate 2a is now able to enter the second catalytic cycle. After oxidation of 2a and subsequent deprotonation, the α-aminoalkyl radical R2a is formed selectively. The latter undergoes a 6-endo-trig cyclization, leading to the bicyclic α-ester radical RE3a whose calculated reduction potential (Ered = -0.77 V SCE, see supporting information for details) is in good agreement with the experimental value of Ered = -0.66 V SCE reported for the secondary α-ester radical CH3CH(•)CO2Me. This allows for its facile reduction by the Ir(II) species, thus closing the second catalytic cycle. exo-Selective protonation of the transient enolate ultimately delivers the desired bicyclic product 3a.