The multifaceted chemistry of [2.2]paracyclophane-based thioethers with palladium(II) complexes

The reactions of planar chiral ([2.2]paracyclophan-4-yl)methyl thioethers ([2.2]PCP-CH2-SR) with various palladium(II) sources (PdL2) were studied. Unexpectedly, with most of the sulfur substrates investigated (SR=Ph, 2-pyridyl, Me, n-dodecyl), and independently of the PdL2 salt employed (L=TFA, OAc, OPiv, Cl, Br), loss of the SR sulfanyl unit, along with incorporation of one palladium L ligand to the lateral benzylic position of the [2.2]PCP core, has been observed. In contrast, the precursor featuring a t-butylsulfanyl group (R=t-Bu) exhibited a distinct reactivity. An ortho C(sp2)−H activation took place, and allowed the formation of a [2.2]paracyclophane-based SC-palladacycle, in an efficient and highly diastereoselective manner (83 % yield, single diastereoisomer).