[overalkylation] [poor reactivity for sterical-hindered substrates] Through extensive screening of reaction conditions, we identified an effective protocol that resulted in the formation of the desired amine (25) with an 85% isolated yield (NMR yield 94%) within 2 h (Table , entry 1). This operationally simple process involved mixing a solution of the three starting materials (22, 23 and 24) with the additive tert-butylcatechol (TBC) in hexafluoroisopropanol (HFIP) as the solvent, irradiated with 420 nm light. In this process, nbutylboronic acid was hypothesized to be converted to boronic tert-butylcatechol ester (Bcat) in situ. Detailed optimization procedures can be found in the Supporting Information, with selected experiments summarized in Table . The utilization of less electron-rich catechols (entries 3, 4), or a reduced amount of TBC (entry 5) led to lower yields. Light irradiation was crucial, as exemplified in entries 6-11 for substrate 25, with 420 nm being the optimal wavelength. Other polar solvents, when used instead of fluoro-substituted alcohols, afforded little product formation (entries 12, 13). The acidity of HFIP presumably facilitated the formation of the proposed EDA complex intermediate 20 from iminium ions and n-BuBcat intermediate. The reaction did not require an inert atmosphere, but increased yields were observed after degassing of the reaction mixture (purging with argon). (entry 14). Furthermore, we successfully extended this transformation to more commercially accessible alkyl trifluoroborate salts and boron pinacol esters, highlighting the synthetic versatility of this method. The alkyl trifluoroborate salts exhibited similar reactivity as boronic acids (entry 15). However, a longer reaction time (12 h instead of 2 h) was required for boron pinacol esters, potentially owing to a slower generation of nBuBcat species, as a catechol/pinacol ligand exchange was involved (entry 16).