Reaction of Oxocyclobutenyl Palladium(II) Complex with Terminal Alkynes or Organozincs Affording Differently 2,3-Disubstituted Cyclobutenones

The reaction of the oxocyclobutenyl palladium(II) complex 2 with terminal alkyne 3 in the presence of CuI or with organozincs yielded differently 2,3-disubstituted cyclobutenones 4 or 5 via the stoichiometric Sonogashira- or Negishi-type reactions, respectively. In addition, the possibility of the synthesis of cyclobutenones 4 from 1, CO, and 3 catalyzed by the Pd complex was also demonstrated.