Olefin maleic anhydride, electron-withdrawing

With fumaronitrile and maleic anhydride, IR spectra, after adding olefin and HCN to NiL3, showed only the very stable (olefin)NiL2 complexes. In these cases the oxidative addition of HCN is evidently suppressed by the strongly electron withdrawing character of the olefins. Small amounts of the reduction products were detected by GC/MS after the solutions had stood for a day, however. The failure of allyl chloride to hydrocyanate is no doubt due... 

The use of the CFs-substituted oxazole as an aza-diene for a Diels-Alder reaction was briefly examined. Thus, prolonged heating of the mixture of 5-ethoxy-4-trifluoromethyloxazole and an excess of acrylic acid afforded the CFs-substituted pyridine derivative in reasonable yield [61], However, cycloaddition with other olefins, such as ethyl acrylate, N-phenylmaleimide, 2,5-dihydrofuran, maleic anhydride, and 2-buten-4-olide did not take place to any appreciable extent presumably because of the deactivation of the oxazole ring by a strongly electron-withdrawing CF3 group. 

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