Alkylation reactions with organometallic compounds. II. The reaction of diphenylacetylene with palladium compounds of the type L₂PdCl₂ and CH₃MgBr

α,α′-Dimethylstilbene is obtained in the reaction of diphenylacetylene with CH₃MgBr and L₂PdCl₂ (L = benzonitrile or norbornadiene), in 65% yield based on the alkyne. Stilbene and α-methylstilbene form as side products (~25%). No reaction takes place when phosphines or arsines are present as L in L₂PdCl₂. The addition of strong nucleophiles like Ph₃P, Ph₂PCH₂CH₂PPh₂ or (PhO)₃P to a cold mixture (-70°) of (C₆H₅CN)₂PdCl₂ and CH₃MgBr yields the corresponding L₂Pd(CH₃)₂, indicating the presence of methyl-palladium components in the reaction reagent and offering thereby a convenient synthesis of these compounds.