Amino acid ionic liquids as catalysts in a solvent-free Morita–Baylis–Hillman reaction

Abstract

In the present work, we describe the preparation of ten amino acid ionic liquids (AAILs) formed from ammonium salts as cations, derivatives of glycerol, and natural amino acids as anions. All of them are viscous oils, colorless or pale yellow, and hygroscopic at room temperature. They have appreciable solubility in many protic and aprotic polar solvents. The AAILs were used as catalysts in a Morita-BaylisHillman (MBH) reaction. The ionic liquids derivative from L-proline and L-histidine demonstrated the ability to catalyze the reaction between methyl vinyl ketone and aromatic aldehydes differently substituted in the absence of an additional co-catalyst under organic solvent-free conditions. The AAIL derivatives from L-valine, L-leucine, and L-tyrosine catalyzed the MBH reaction only in the presence of imidazole. The MBH adducts were obtained in moderate to good yields. Although the catalytic site in the ILs was in its enantiomerically pure form, all the MBH adducts were obtained in their racemic form.

Engineering the simply asymmetric Morita–Baylis–Hillman reactions in a sodium phosphate buffer system: from enzyme‐ to proline‐catalyzed transformation

“…With reference to the generally accepted chemically catalyzed mechanism of the MBH reaction, 9,14 the catalytic mechanism of L-Pro-and D-Pro-catalyzed asymmetric MBH reaction in a sodium phosphate buffer was proposed here (Fig. 5).…”

“…6 Further improvement can be observed when the three important factors (activated alkene, electrophile and catalyst) governing the reactions are successfully combined, as well as the cooperative effect of hydrogen bonding additives such as phenols, alcohols and ionic liquids. [13][14][15][16] Most MBH reactions still suffer disadvantages such as use of hazardous solvents, high amounts (typically up to 100% mol) of the nucleophilic catalyst, long reaction time, low reactivity and selectivity. 9 These limitations have precluded its general use under large-scale conditions.…”

Feasibility of 1-Ethyl-4-butyl-1,2,4-triazolium Acetyl Amino Acid Ionic Liquids as Sustainable Heat-Transfer Fluids

“…Using triazolium, both 1,2,3-triazolium and 1,2,4-triazolium, instead of imidazolium as a cation, can avoid this situation. − Since hazardous azides are frequently used in the synthesis of 1,2,3-triazole and its derivatives, 1,2,4-triazole is the more appropriate cation choice . Amino acids have been reported as biocompatible anions for ILs with multiple applications. − However, the thermal stability of amino acid IL is lower than that of conventional anions, which is one of the main factors affecting its wide applications. Bhattacharyya et al found that the thermal stability and heat capacity of acetyl amino acids are greater than the corresponding amino acids .…”

Cascade embedding triethyltryptophanium iodide ionic liquid (TrpEt3+I−) on silicated titanomagnetite core (Fe3‐xTixO4‐SiO2@TrpEt3+I−): A novel nano organic–inorganic hybrid to prepare a library of 4‐substituted quinoline‐2‐carboxylates and 4,6‐disubstituted quinoline‐2‐carboxylates

“…Amino acid ionic liquids (AAILs) were utilized recently in many aspects of scientific and technological fields as lubricants, [ 41 ] metal Scavenging, [ 42 ] ligand‐exchange chiral separations, [ 43 ] CO 2 absorbants, [ 44 ] and self‐assembly media of amphiphiles. [ 45 ] The catalytic efficacy of some AAILs observed in the Morita–Baylis–Hillman reaction, [ 46 ] Knoevenagel condensation, [ 47 ] thiol‐Michael addition, [ 48 ] and Baeyer–Villiger oxidation of cyclic ketones. [ 49 ]…”