| 摘要 |
Diels-Alder diene synthesis reactions are effected in the presence of at least one liquid quaternary ammonium or phosphonium salt of formula Q<+>.A<-> (I). Q = quaternary ammonium or phosphonium; A = anion. (I) is preferably N-butyl pyridinium hexafluorophosphate, N-ethyl pyridinium tetrafluoroborate, tetrabutyl phosphonium tetrafluoroborate, 3-butyl-1-methyl imidazolium hexafluoroantimonate, hexafluorophosphate or trifluoromethyl sulphonate, pyridinium fluorosulphonate, trimethyl phenyl ammonium hexafluorophosphate, 3-butyl-1-methyl imidazolium dichlorocuprate, pyridinium tetrachloroborate or 3-butyl-1-methyl imidazolium tetrachloroaluminate or trichlorozincate.
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