Based on our investigations and our previous work, we proposed the following mechanism (Scheme 2C). Initially, the photocatalyst, Ph-benzoPTZ, is excited with 405 nm light. The excited state PC* (Eox* = -1.97 V vs SCE) can undergo single electron transfer (SET) with the commercially available cobalt(II) salen (Ered = -1.60 V vs SCE) to form the corresponding radical cation PC •+ and Co I species. It was verified by Stern-Volmer quenching experiment that PC* can be quenched by Co II (see supporting information). The PC •+ can then be reduced by the cyclohexyl-substituted Hantzsch ester (HEH-Cy) to restore the ground state of photocatalyst, completing the photocatalysis cycle and yielding radical cation, HEH-Cy •+ (which fragments to form a cyclohexyl radical that is a spectator in most reactions -see Scheme 4). Meanwhile, the key Co III -H species is generated through protonation of Co I . Following hydrogen atom transfer (HAT) from Co III -H to starting material 1, an alkyl radical intermediate I is formed together with Co II , completing the MHAT catalysis cycle. Then, in the selectivity determining step, the alkyl radical reacts at the ipso position of the sulfonyl aromatic ring, giving aryl radical II. Rapid radical C-S bond breaking (III), followed by N-desulfonylation follows to generate a nitrogen-centred radical IV, which undergoes reduction and protonation to yield the final product. Without the addition of 2,6-lutidine and HFIP, yields were diminished and only starting material was recovered in the absence of the photocatalyst, cobalt catalyst, Hantzsch ester, or light (see supporting information for more details). Next, we probed the possible variation in migrating aromatic group (Scheme 3a), starting with monosubstituted sulfones bearing electron-withdrawing and electron-donating groups at the orthoposition. A range of functional groups including halogens, trifluoromethyl and ester groups were all well tolerated to deliver the corresponding -arylethylamines in moderate to good yields (2c-2h, 2k, 2l). Substrates where the migrating aryl group is di-ortho substituted also performed well, giving the products in good yields (2b, 2i, 2j, 2m, 2n). Notably, substrates with large steric groups, such as 1m and 1n, were also suitable for this reaction providing access to sterically congested products in a straightforward manner. Substrates containing a fused ring and heterocyclic ring were compatible with the reaction system to form 2r and 2s in 42% and 17% respectively. The low yield of 2s was due to incomplete consumption of the starting material. Substrates without ortho position substituents were also evaluated (2a, 2o-2q), demonstrating that a para electron-withdrawing group could improve the reaction efficiency to some extent. Then we turned our attention to substrates with diverse aniline moieties. Substrates bearing different groups at meta-and para sites on the aniline (2t-2ad) furnished the targeted products in good yields.