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The [4+2] annulation represents an elegant and versatile synthetic protocol for the construction of benzene rings. Herein, a strategy for visible‐light induced [4+2] annulation of thiophenes and alkynes, to afford benzene rings, is presented. Under simple and mild reaction conditions, the ready availability and structural diversity of thiophenes and alkynes permit the facile synthesis of several substituted aromatic rings. Valuable drugs and amino acids are also well tolerated. Moreover, DFT calculations explain the high regioselectivity of the reaction. [ABSTRACT FROM AUTHOR]

Visible-light-mediated formation of furans though direct oxidative [3+2] cycloaddition of 1,3-diones and alkynes is described. This protocol provides a simple and mild route to poly-substituted furans in moderate-to-good yields. Preliminary mechanistic studies suggest that this reaction likely follows a radical addition/cyclization pathway. [ABSTRACT FROM AUTHOR]

Direct radical additions to terminal alkynes have been widely employed in organic synthesis, providing credible access to the anti-Markovnikov products. Because of the Kharasch effect, regioselective control for the formation of Markovnikov products still remains a great challenge. Herein, we develop a transition-metal-free, visible light-mediated radical addition of S-nucleophiles to terminal alkynes, furnishing a wide array of α-substituted vinyl sulfones with exclusive Markovnikov regioselectivity. Mechanistic investigations demonstrated that radical/radical cross-coupling might be the key step in this transformation. This radical Markovnikov addition protocol also provides an opportunity to facilitate the synthesis of other valuable α-substituted vinyl compounds. [ABSTRACT FROM AUTHOR]