Pd-catalyzed, cu(I)-mediated cross-couplings of bisarylthiocyclobutenediones with boronic acids and organostannanes

Bisarylthiocyclobutenedione 7 reacted smoothly with a variety of both organostannanes and (hetero)arylboronic acids in the presence of a catalytic amount of Pd and a stoichiometric amount of CuTC to produce symmetrical disubstituted cyclobutenediones in yields that range from 37 to 94% (18 examples).