(S)-4-tert-Butyl-2-phenyl-2-oxazoline derived palladacycles as efficient catalysts for the decomposition of P=S pesticides

Three palladacycles with N, N-trans coordination, (S)-{2-[2-(4-tert-butyl) oxazolinyl]phenyl-C1, N}(4-R-pyridine)(aqua)npalladium(II) triflate (R = CF ₃, n = 1, 1; R = H, n = 0, 2; R = NMe2, n = 1, 3), have been prepared from the respective chloride precursors and were characterized with IR and 1H-NMR and elemental analyses. The crystal structures of 2 and a pincer complex (S, S)-{2, 6-bis[2-(4-iso-propyl)oxazolinyl]phenyl-N, C₁, N}bromo-palladium(II) hydrate (5) were determined. For methanolysis of P=S pesticides, it was found that ortho-palladated complexes 1-3 effectively catalyzed the reaction; however, the pincer complex 4 with triflate counterion was much less active. Relative to the methoxide-promoted background reaction at ^s_sPH 10.80, 1 mmol L^-1 of palladacycles 1-3 can accelerate the methanolysis by 8.7 × 10⁹, 1.5 × 10 ⁹, and 1.0 × 10⁸-fold, respectively. For racemic P=S pesticides, such as letophos and EPN, it proved that there is no clear chiral discrimination during the catalysis. The reaction mechanism of the catalytic methanolysis was discussed according to the experimental results.