Initially, we hypothesised that the extension of the transformation to include "activated" alkenes, such as styrenes, would be challenging, as these compounds are known to be susceptible to oxidation by the photocatalyst. Although this was indeed observed, styrene-type substrates typically exhibited an improved yield in the reaction due to their enhanced reactivity with the BCB radical cation (Table ). Despite involving a direct interaction with an electron-deficient radical cation intermediate, styrene-type alkenes bearing both electron-donating and electron-withdrawing groups were viable in this transformation, and all delivered the desired products as single regioisomers (5a-h). Additionally, highly versatile functional handles such as halides (5i-l), carboxylic acids (5m) and boronic esters (5n) could also be tolerated under the reaction conditions, providing the potential for further derivatisation of these substrates. When exploring the effect of alkene substitution, it was again observed that cyclic 1,2-disubstituted substrates are capable of accessing the desired BCH products, exclusively as the cis-diastereomer (5o-q). In the case of acyclic (E)-1,2-disubstituted olefins, only the trans-isomer is detected (5r-s), with the stereochemistry confirmed by X-ray crystallography. The limit of reactivity was located when highly electron-deficient Michael-type alkenes were observed to be unsuitable for this transformation (5t), making this approach complementary to previously reported radical-based BCB [2π+2σ] cycloaddition reactions . However, subjecting 1,1-disubstituted and trisubstituted alkenes to the newly developed reaction conditions could provide access to highly substituted BCH substrates 5u, 5v and 5w, although tetrasubstituted alkenes were too sterically hindered to deliver the desired cycloadduct (5x).