Condensation of aromatic (heteroaromatic) aldehydes with 1,3 dicarbonyl com pounds under the 1 butyl 3 methylimidazolium tetrafluoroborate ([Bmim][BF 4 ]) ionic liq uid-piperidinium acetate catalytic system (0.2 equiv. of each component) in the absence of a solvent affords, depending on the structures of the reagents, 2 arylidene derivatives of methyl acetoacetate and acetylacetone, diethyl 2,4 bis(trifluoroacetyl) 3 phenylpentanedioate, or di methyl 2 aryl 4 hydroxy 6 oxocyclohexane 1,3 dicarboxylates. The reactions of the resulting 2 arylidene derivatives with O methylisourea in the [Bmim] [BF 4 ] ionic liquid produced me thyl 2 methoxy 4 methyl 6 aryldihydropyrimidine 5 carboxylates and 1 (2 methoxy 4 me thyl 6 phenyldihydropyrimidin 5 yl)ethanone (mixtures of 3,6 and 1,6 dihydro isomers), which were transformed into the corresponding 3,4 dihydropyrimidin 2(1H ) one derivatives.
Tri-and tetraalkylammonium, 1,3-dialkylimidazolium, and 1,2,3-trialkylimidazolium salts with BF 4 -, PF 6 -, AlCl 4 -, and Al 2 Cl 7 as counterions catalyze the Biginelli reaction, ensuring preparation of various 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine-2(1H)-thione derivatives in high yields in the absence of a solvent.
Pyrimidine derivatives R 0510 Alkylammonium and Alkylimidazolium Perhaloborates, Phosphates, and Aluminates as Catalysts in the Biginelli Reaction. -Among 10 title catalysts investigated, the salts shown in the scheme afford the best yields. -(PUTILOVA, E. S.; KRYSHTAL', G. V.; ZHDANKINA, G. M.; TROITSKII, N. A.; ZLOTIN, S. G.; Russ.
Presence of 1-Butyl-3-methylimidazolium Tetrafluoroborate -[13 examples]. -(PUTILOVA, E. S.; TROITSKII, N. A.; ZLOTIN, S. G.; KHUDINA, O. G.; BURGART, Y. V.; SALOUTIN, V. I.; CHUPAKHIN, O. N.; Russ.
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