Coordination and reactivity of benzyloxycarbonyl-Ala(CN)-OR (R = H, CH3) in complexes of platinum (II)

Article abstract of DOI:10.1016/0020-1693(96)05126-2

The conversion of a nitrile to an oxazoline group in an amino acid side chain promoted by platinum(II) was investigated. While benzyloxycarbonyl-β-cyano-alanine (Z-Ala(CN)-OH) did not give any evidence of coordination of the nitrile group to Pt(II) in different complexes, the corresponding methyl ester Z-Ala(CN)-OCH₃ readily afforded the Pt(II)-nitrile complex trans-[Pt(CF₃){Z-Ala(CN)-OCH₃}(PPh₃) ₂][BF₄] in good yield by reaction with the cationic derivative trans-[Pt(CF₃)(PPh₃)₂(solv)][BF₄] (solv = CH₂Cl₂). The reactivity of the CN group in the complex trans-[Pt(CF₃){Z-Ala(CN)OCH₃}(PPh₃) ₂] [BF₄] with ClCH₂CH₂O-to form the oxazoline ligand 2 was examined. The presence of the oxazoline ring in the final products was evidenced by IR, ¹H and ¹³C NMR data and confirmed by FAB and MALDI mass spectra, but its isolation was hampered by the cleavage of the oxazoline ring under the chromatographic conditions applied.