The reaction of aromatic aldehydes 1 with 5, 5-dimethyl-1, 3-cyclohexandione 2 was investigated in this paper by using [bmim][BF4] as the reaction medium. It was found that when the reaction was carried out in the presence of catalytic amount of FeCl3·6H2O, xanthenediones 3 was obtained in high yields. On the other hand, when a combination of trimethylchlorosilane (TMSCl) and FeCl3·6H2O was employed as the catalyst, the reaction afforded ring-opening derivatives of xanthenediones 4 with high efficiency.
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