Nitrogen-containing moieties, specifically aryl-and heteroaryl-amines (e.g. 1), are omnipresent in state-of-the-art high-throughput screening (HTS) libraries and bioactive molecules 1 . The synthetic ease of forming the C-N bond with ubiquitous aromatic coupling partners 2 has greatly facilitated their prevalence. Recent advancements in medicinal chemistry have shifted focus towards compounds with high fraction of C(sp 3 )-rich, as they exhibit improved physicochemical and pharmacokinetic properties (Figure ). This has led to an exploration of methods to access three-dimensional chemical spaces , including novel methods to make caged hydrocarbons, such as bicyclopentanes 5 and cubanes . Despite these advancements, efficient methods to access complex, C(sp 3 )-rich amines (e.g. 2-4) remain rare. Conventional twocomponent methods for their synthesis include transition metal-catalyzed C-N cross-coupling reaction , reductive amination of aldehydes or ketones , N-alkylation of amines , and imine addition (Figure ). While these methods offer access to simple alkyl amines, they pose challenges in rapidly synthesizing more complex aliphatic amines and constructing amine libraries for structure activity relationship (SAR) studies . In recent decades, the versatility of imines has led to a significant progress in the development of multicomponent reactions as flexible routes to amine synthesis , such as aza-Morita-Baylis-Hillman 15 , Mannich , Petasis boron-Mannich (PBM) and Strecker 18 reacion. Among these, the three-component PBM reaction, first reported in 1993 , has been an attractive method for medicinal chemists due to its ability to use widely available building blocks including amines, aldehydes, and aromatic boronic acids to rapidly access diverse C(sp 2 )-rich chemical space . However, PBM reaction remained underutilized because the substrate scope has been mainly restricted to activated aldehydes with adjacent heteroatoms as directing groups and aryl or alkenyl boronic acids. As most reactions of this class are mediated by a 2e -mechanism where alkyl migration is unlikely to happen , extending this reactivity to unactivated alkyl boronates, to "escaping from the flatland" 3 , has been a challenge. A strategy that combines the diversity of a general PBM reaction with alkyl boronic coupling partners exponentially increases the accessibility of C(sp 3 )-rich alkyl amines (Figure , m×n×p hypothetical products in a 3D library). Such a method would enable holistic structural diversity coverage for complex aliphatic amines that could facilitate the comprehensive SAR probing and the development of drug candidates . Despite some recent advance of PBM reaction with alkyl boronates have been achieved through radical addition process, where stabilized imine intermediate is often required 11 , a more general alkyl Petasis boron-Mannich (APBM) reaction is highly desirable. Instead of previous elegant reports using alkyl radicals addition to iminium ions to access alkyl amines , we posed an alternative hypothesis that involves an electron donor-acceptor (EDA) complex and sequential radical-radical coupling process. This tactic aims to provide a universal solution for the APBM reaction (Figure ). On investigating the oxidative potentials of various alkylboron ate-complex species (Figure ) 23 , catechol installation was identified as a mild method to activate boron without the need for strong bases, inspired by Renaud and Aggarwal's seminal studies 24 . Therefore, the corresponding alkyl boronate complexes with low oxidative potentials (Ep = ~ 0.49 V, versus a saturated calomel electrode (SCE)) were anticipated to undergo facile single-electron oxidation (Figure ). Since the photo-excited iminium ions were found to function as strong oxidants , it was postulated that the in-situ generated catechol boron ester ate-complexes could be oxidized, resulting in the generation of alkyl radicals. These alkyl radicals would subsequently undergo radical-radical coupling with a-amino radicals to yield the desired aliphatic amines (Figure ).