M(NTf2)2 (M = CoII, NiII, CuII, ZnII)を触媒として用いたBiginelli型縮合反応　

抄録

Biginelli reactions are simple one-pot but low-yielding condensations of dicarbonyl compounds with aldehydes and urea or thiourea in the presence of catalytic amount of acid to produce 3,4-dihydropyrimidin-2- (1H)-ones. Recently, to improve the efficiency of this reaction, modifications using Lewis acids have been reported. However, some of these procedures involve difficulties such as the use of stoichiometric amounts of catalysts, high temperatures and so on. Here we report efficient Biginelli type condensation reactions using Ni(NTf2)2 and Cu(NTf2)2 as a Lewis acid catalyst. This study demonstrates that these Lewis acid can catalyze the Biginelli type reactions efficiently in protic solvents such as MeOH and water. It is noteworthy that the efficiency of the catalysts M(NTf2)2 was considerably improved by adding HNTf2.

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