Visible-Light Mediated Activation of 1,3-Dienes and Allenes via Energy Transfers

Nature has inspired chemists toward the development of photocatalytic processes. By harvesting visible light, chemists can access alternative reaction pathways that bypass traditional thermal methods. Energy transfer (EnT) stands out for enabling the activation of otherwise inert substrates, generating the corresponding triplet states. This review highlights and compare the recent advances in EnT-mediated activation of conjugated 1,3-dienes and allenes (cumulated 1,2-dienes), which represent an underdeveloped avenue for synthetic purposes. These approaches enable novel transformations, ranging from photoisomerization to challenging cycloaddition. These findings can have broad implications across synthetic chemistry and materials science, offering energy-efficient and atom-economical routes to complex molecular architectures. Studies employing indirect functionalization, in which these motifs are not directly activated via EnT, are explicitly excluded from this review.