bonds, showing remarkable levels of regioselectivity even in complex drug-like molecules (Scheme 1C). In HAT photocatalysis, a catalyst converts light energy into chemical energy for the homolytic cleavage of strong aliphatic C-H bonds. Especially, the decatungstate anion ([W10O32] 4-) has shown remarkable selectivity for specific C(sp )-H bonds, governed by an intricate balance between steric and electronic interactions. We envisioned that the regioselective introduction of an allyl moiety onto hydrocarbon frameworks would be particularly useful as it provides a convenient branching point for further late-stage synthetic exploitation (Scheme 1B). To install such moieties, radical allylation has manifested itself as a valuable strategy. One approach relies on the use of transition metal complexes to activate a substrate containing an allylic leaving group to afford a -allyl complex, which is then suited to trap a C-centered radical (Scheme 1D). This strategy can engage a diverse set of allyl coupling partners but typically requires purposely designed radical precursors, which prevents the direct allylation of unactivated C(sp )-H bonds. SOMOphilic allylation constitutes another tactic and exploits radicofugal groups X (e.g., X = halide, SO2R, SnR3) in the allylic position to afford the desired product via a radical addition/fragmentation process (Scheme 1D). However, while synthetically useful, the reaction scope is mainly restricted to the synthesis of 1,1-disubstituted olefins. Seeking to address these challenges, we sought to develop a robust and versatile synthetic platform for the allylation of strong aliphatic C(sp )-H bonds. Hereto, a modular synthetic sequence is preferred in which the allyl moiety is assembled in a stepwise fashion, enabling the rapid generation of structurally diverse analogues. Specifically, our sequence features the merger of two distinct synthetic steps to accomplish this goal (Scheme 1 E). First, we planned to activate C(sp 3 )-H bonds via decatungstate-catalyzed hydrogen atom transfer and subsequently trap the resulting C-centered radical with a vinyl phosphonate. The ensuing radical addition product serves as a suitable linchpin for the second step, in which a classical Horner-Wadsworth-Emmons (HWE) olefination is able to deliver the targeted allylated compounds. In order to streamline these two steps, we reasoned that a telescoped flow protocol would be indispensable not only to accelerate access to these valuable building blocks but also to ensure facile scalability. Herein, we report the successful realization of such a flow platform enabling both early-stage and late-stage allylation of a wide range of hydrocarbons. During the writing of this manuscript, Silvi et al. reported a one-pot strategy to obtain 1,2-disubstituted olefins via a visible-light driven decarboxylative strategy merged with the Wittig reaction. Our investigations commenced with the decatungstate-enabled hydroalkylation of ethyl 2-(diethoxyphosphoryl)acrylate (2) using cyclohexane as the H-donor (See Supporting Information, Table ). Following a careful optimization of different reaction parameters, we found that the photocatalytic radical addition performed optimal in continuous-flow using a commercially available Vapourtec UV-150 photochemical reactor (PFA (perfluoroalkoxy) capillary, ID: 0.75 mm; V = 3.06 mL, flow rate = 0.612 mL min -1 , r = 5 min) equipped with a 60 W UV-A LED light source, which matches the measured absorption spectrum of decatungstate. A 65% NMR yield (64% after isolation) was obtained for the targeted hydroalkylated compound when a CH3CN solution of the acrylate (0.1 M), cyclohexane (20 equivalents) and tetrabutylammonium decatungstate (TBADT, (Bu4N)4[W10O32]) as the photocatalyst (1 mol%) was irradiated for 5 minutes (See Supporting Information, Table , Entry 9). Other HAT photocatalysts, such as Eosin Y, anthraquinone, 5,7,12,14pentacenetetrone and fluorenone, were also evaluated, but failed to deliver the targeted product. Interestingly, benzophenone showed a comparable activity to the decatungstate anion, although only when used at high catalyst loading (20 mol%, 68% NMR yield). In addition, since benzophenone also dimerizes to give pinacol upon UV-A irradiation, we selected TBADT as the ideal photocatalyst for the targeted hydroalkylation reaction. Notably, this transformation is quite general and a diverse set of alkylphosphonates (3) could be readily isolated and characterized (see Supporting Information, Section 6).