Interaction of PdCl₂-2-(β-diphenylphosphine)ethylpyridine Complex with Diols and CO: Synthesis of New Alkoxycarbonyl Complexes, Key Intermediates to Cyclic Carbonates

PdCl2PN (PN = 2-(β-diphenylphosphine)ethylpyridine) was found to be effective in the promotion of the alkoxycarbonylation of diols [(1,2-hydroxyethane (HE); 1,2- and 1,3-hydroxypropane (1,2HP, 1,3HP), 1,2-, 1,3-, and 1,4-hydroxybutane (1,2HB, 1,3HB, 1,4HB)]. The relevant mono-alkoxycarbonyl complexes of the diols, of formula PdClPN(COO-R-OH), were isolated, characterized in solution, and studied for their reactivity. All complexes in the presence of different reagents release the alkoxycarbonyl group directly as cyclic carbonate or as chloroformate, which “in situ” converts into cyclic carbonate or other valuable carbonyl products. The structure of the complexes PdCl[(COO-CH2-CH2-CH2(OH)](PN) (4c) and PdCl(COO-CH2-CH(OH)-C2H5)(PN) (4d) was also derived by single-crystal X-ray diffraction.