An Unusual Palladium Complex Involved in an Unusual Rearrangement of Ortho-Palladated Aryldithioacetals

The reaction of 1 with Pd(dba)2, Tl(TfO) and PPh3 in 1:1:1:2 molar ratios to give 3 implicates (i) an oxidative addition reaction, (ii) a rearrangement involving the cleavage of one HC−S bond and formation of an aryl-S bonds, and (iii) coordination of the Pd(PR3)2 group with a ligand intermediate between η2-[ArCHS(+)To] and κ2-C,S-ArCH(-)STo, which requires the consideration of 3 as intermediate between a Pd(0) and a Pd(II) complex. The coordination of the ligand as a chelating three-membered ring, instead of the expected five-membered ring involving C(10) and S(1), and the partial intramolecular redox process are explained as a consequence of the transphobia of the pair of ligands Ph3P/CH(STo)Ar.