Ni-catalyzed non-activated C-S bond cleavage at ambient temperature for the synthesis of sulfur-containing polycyclic compounds.

A Ni-catalyzed intramolecular reaction of diarylthioether-tethered 1,8-diynes gave sulfur-containing tetracyclic compounds at ambient temperature. The transformation was initiated by non-activated sp2 C-S bond cleavage along with consecutive alkyne insertions. A double intramolecular reaction of a tetrayne and an intermolecular reaction of monoynes were also available, and the corresponding polycyclic compounds were obtained. Moreover, the obtained cycloadduct showed photo-catalytic activity in benzylic oxidation.

Consecutive HDDA and TDDA reactions of silicon-tethered tetraynes for the synthesis of dibenzosilole-fused polycyclic compounds and their unique reactivity.

Silicon-tethered tetraynes possessing a 1,3-diyne moiety underwent consecutive hexadehydro- and tetradehydro-Diels-Alder reactions to give a series of fused polycyclic aromatic compounds containing a dibenzosilole skeleton. The benzene ring in the product acted as a 1,3-diene and reacted with the active alkyne as well as oxygen to provide [4 + 2] cycloadducts.

Intramolecular Consecutive Dehydro-Diels-Alder Reaction for the Catalytic and Enantioselective Construction of Axial Chirality.

Consecutive thermal and metal-catalyzed dehydro-Diels-Alder (DDA) reactions of sulfur-tethered tetraynes, possessing a 1,3-diyne moiety, proceeded efficiently, and axial chirality was achieved for the resulting dibenzothiophenyl moieties. Chiral-rhodium catalysis realized a highly enantioselective synthesis, and transformations into bis(benzocarbazole) derivatives were also achieved.