The insertion of dimethyl acetylenedicarboxylate into an S-Pd bond

The first definitive evidence of insertion of an alkyne into an S-Pd bond has been presented. The reaction of Pd(SAr)(2)(DPPE) with dimethyl acetylenedicarboxyl ate (DMAD) gave the cis-insertion product (Z)-Pd-[C(CO2Me)=C(SAr)(CO2Me)](SAr)(DPPE), whose structure was unambiguously determined by X-ray crystallographic analysis.