Alongside the switching behaviour of dihydro-4Hcyclobuta [c]isochromenes and 1H-2-benzo [c]oxocins, these compounds are important substructures found in several bioactive molecules/enzymes that are difficult to access synthetically. The same holds for dihydronaphthalenes, which are formed upon prologued heating of these compounds. While some reports of thermally-promoted and UV-irradiation-induced [2+2] cycloaddition reactions are known to yield cyclobutaisochromenes, most of these transformations have a low efficiency due to unwanted side-product formation and/or isomerization. As for the synthesis of dihydronaphthalenes, most reported strategies focus on the dearomatization of naphthalenes in low/moderate yields due to the relative instability of dihydronaphthalenes compared to the naphthalene [c]oxocin/dihydro-4H-cyclobuta [c]isochromene photoswitches, and transformations to dihydronaphthalenes under certain conditions. starting material. As a result, these transformations have a limited scope, being largely restricted to formation of dihydronaphthalenes bearing electron-withdrawing functionalities. In this paper, we disclose efficient synthetic protocols to construct both dihydro-4Hcyclobuta [c]isochromenes and dihydronaphthalenes, starting from 1H-2-benzo [c]oxocins. Specifically, we report the visible-light induced intramolecular [2+2] cyclization of 1H-2-benzo [c]oxocins to dihydro-4Hcyclobuta [c]isochromenes, and thermal ring-contraction of 1H-2-benzo [c]oxocins to produce dihydronaphthalenes (Figure , bottom). In the spirit of green chemistry, all transformations reported in this paper are based on simple protocols that involve only light or heat, proceed to the desired products in near quantitative yields with excellent chemoselectivity, under mild conditions, while exhibiting high atom economy.