| Abstract |
Free nitriles NCCH2R (1a R = CO2Me, 1b R = SO2Ph, and 1c R = COPh) with an acidic alpha-methylene react with acyclic nitrones -O+N(Me)C(H)R (2a R = 4-MeC6H4 and 2b R = 2,4,6-Me3C6H2), in refluxing CH2Cl2, to afford stereoselectively the E-olefins (NC)(R)CC(H)R (3a-3c and 3a -3c ), whereas, when coordinated at the platinum(II) trans-[PtCl2(NCCH2R)(2)] complexes (4a R = CO2Me and 4b R = Cl), they undergo cycloaddition to give the (oxadiazoline)-Pt-II complexes trans-[PtCl2\N=C(CH2R)ON(Me)C(H)R \(2)] (R = CO2Me, Cl and R = 4-MeC6H4, 2,4,6-Me3C6H2) (5a-5d). Upon heating in CH2Cl2, 5a affords the corresponding alkene 3a. The reactions are greatly accelerated when carried out under focused microwave irradiation, particularly in the solid phase (SiO2), without solvent, a substantial increase of the yields being also observed. The compounds were characterized by IR and H-1, C-13, and Pt-195 NMR spectroscopies, FAB(+)-MS, elemental analyses and, in the cases of the alkene (NC)(CO2Me)CC(H)(4-MeC6H4) 3a and of the oxadiazoline complex trans-[PtCl2\N=C(CH2Cl)ON(Me)C(H)(4-C6H4Me)\(2)] 5c, also by X-ray diffraction analyses. |
