Switchable Copper-Catalyzed Approach to Benzodithiole, Benzothiaselenole, and Dibenzodithiocine Skeletons.

A copper-catalyzed reaction between 2-bromo-benzothioamides and S or Se involving sulfur rearrangement is reported, enabling access to benzodithioles and benzothiaselenoles in the presence of CsCO. In the absence of S or Se, the reaction affords dibenzodithiocines via two consecutive C(sp)-S Ullmann couplings.

Synthesis of Substituted 4 H-Thiochromen-4-imines via Copper-Catalyzed Cyclization Cascades of o-Bromobenzothioamides with Terminal Alkynes.

A series of ( E)- N-aryl-4 H-thiochromen-4-imines has been conveniently obtained through a cascade reaction between o-bromobenzothioamides and terminal alkynes. This novel approach probably involved an initial generation of benzothietane-2-imine intermidates via an intramolecular Ullmann reaction under CuI/L-proline cocatalysis and alkaline conditions followed by imine alkynylation, ring opening, and cyclization sequences to provide the unexpected 4 H-thiochromen-4-imines rather than isothiochromans.