Ionic liquid-phase organic synthesis

Dabiri M, Salehi P, Baghbanzadeh M, Shakouri M, Otokesh S, Ekrami T, Doosti R (2007) Efficient and eco-friendly synthesis of dihydropyrimidinones, bis(indolyl) methanes, and N-alkyl and N-arylimides in ionic liquids. J Iran Chem Soc 4 393 01 Legeay JC, Eynde JJV, Bazureau JP (2008) Ionic liquid phase organic synthesis (loLiPOS) methodology applied to the preparation of new 3,4-dihydropyrimidine-2(lH)-ones bearing bioisostere group in N-3 position. Tetrahedron 64 5328-5335... 

A microwave dielectric heating assisted TSIL phase synthesis [45] of 1,4-dihydropyridines, 3,4-dihydropyrimidin-2(lH)-ones, pyridines and polyhydroquinolines using a TSIL as a soluble support was described. The efficiency of the ionic liquid phase organic synthesis (loLiPOS) methodology was demonstrated by using a one-pot three-component condensation. The stmcture of the intermediates... 

In addition, Bazureau et al. [250] also report the solvent-free synthesis of N-3 functionalized 3,4-dihydropy rimidin-2-(lH)-ones (DHPMs) 159 following an "ionic liquid-phase organic synthesis" (loLiPOS) protocol based on Biginelli condensation (Scheme 85). The tactic involves the attachment of 3,4-DHPM 155 on the ILP-bound acetoacetates in the first step followed by functionalization with 1,2,4-oxadiazole using aliphatic carboxylic anhydrides. 

H. Hakkou, J.J.E. Vanden, J. Hamelina, J.P Bazureau, Ionic liquid phase organic synthesis (loLiPOS) methodology applied to the three component preparation of 2-thioxo tetrahydropyrimidin-4-(lH)-ones rmder microwave dielectric heating. Tetrahedron 60 (2004) 3745-3753. 

Fraga-Dubreuil, J., Famelart, M.-H. and Bazureau, J.P., Ecofriendly fast synthesis of hydrophylic poly(ethyleneglycol)-ionic liquid matrices for liquid-phase organic synthesis, Org. Proc. Res. Dev., 2002,... 

Advances in liquid-phase organic synthesis using functional ionic liquid as supports 07CJO1188. 

J. Fraga-Dubreuil, J.P. Bazureau, Grafted ionic liquid-phase-supported synthesis of small organic molecules. Tetrahedron Lett. 42 (2001) 6097-6100. 

Of the inorganic supports, best results were reported for a mesoporous MCM-41 [337]. Support on ionic-liquid phases has been studied by different groups with variable results [338, 339], Of the non-conventional organic polymers, non-covalent immobilization on poly(diallyldimethylammonium) is notable [340], Catalysts 133 (15 mol.%) promoted the aldol reaction of acetone and benzaldehydes to afford the corresponding (i-hydroxyketones in 50-98% yields and 62-72% ee, which are clearly lower than those reported for other polymer-supported systems. Recycling of the catalysts was possible at least six times without loss of efficiency. More recently, proline has been attached to one DNA strand while an aldehyde was tethered to a complementary DNA sequence and made to react with a non-tethered ketone [341], To date, the work has focused more on conceptual development than on the analysis of its practical applications in organic synthesis. 

In comparison with traditional biphasic catalysis using water, fluorous phases, or polar organic solvents, transition metal catalysis in ionic liquids represents a new and advanced way to combine the specific advantages of homogeneous and heterogeneous catalysis. In many applications, the use of a defined transition metal complex immobilized on a ionic liquid support has already shown its unique potential. Many more successful examples - mainly in fine chemical synthesis - can be expected in the future as our loiowledge of ionic liquids and their interactions with transition metal complexes increases. 

Catalysis at interfaces between two immiscible liquid media is a rather wide topic extensively studied in various fields such as organic synthesis, bioenergetics, and environmental chemistry. One of the most common catalytic processes discussed in the literature involves the transfer of a reactant from one phase to another assisted by ionic species referred to as phase-transfer catalyst (PTC). It is generally assumed that the reaction process proceeds via formation of an ion-pair complex between the reactant and the catalyst, allowing the former to transfer to the adjacent phase in order to carry out a reaction homogeneously [179]. However, detailed comparisons between interfacial processes taking place at externally biased and open-circuit junctions have produced new insights into the role of PTC [86,180]. 

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