- Platinum(IV)-assisted [2 + 3] cycloaddition of nitrones to coordinated organonitriles. Synthesis of Δ4-1,2,4-oxadiazolines
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[2 + 3] cycloaddition between acetonitrile ligands in the platinum(IV) complex [PtCl4(MeCN)2] and the nitrones -O+N(R3) = C(R1)(R2) [R1 = H, R2 = Ph, o-C6H4OH, p-C6H4Me, p-C6H4OMe, p-C6H4NO2, p-C6H4NMe2, p-C6H4NMe2·HCl, R3 = Me; R1 = H, R2 = Ph, Bu, R3 = CH2Ph] proceeds smoothly under mild conditions and gives the first examples of Δ4-1,2,4- oxadiazoline complexes, [PtCl4{N = C(Me)O-N(R3)-C(R1)(R2)}2], as a 1:1 mixture of two diastereoisomers, in 70-90% yields. The heterocyclic ligands were liberated almost quantitatively by reaction at room temperature of the complexes with a slight excess of pyridine in chloroform giving free N = C(Me)O-N(R3)-C(R1)(R2) and trans-[PtCl4(pyridine)2]; subsequent workup allowed the isolation of the novel Δ4-1,2,4-oxadiazolines. All prepared compounds were characterized by elemental analyses, FAB or EI mass spectrometry, and IR and 1H, 13C{1H}, and 195Pt (metal complexes) NMR spectroscopies; X-ray structure determination was performed for the (R,S) diastereoisomer of trans-[PtCl4{N=C(Me)ON(Me)-CH(p-C6H4OMe)}2].
- Wagner, Gabriele,Pombeiro, Armando J. L.,Kukushkin, Vadim Yu.
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p. 3106 - 3111
(2007/10/03)
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