First Evidence of Proline Acting as a Bifunctional Catalyst in the Baylis–Hillman Reaction Between Alkyl Vinyl Ketones and Aryl Aldehydes

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

Polarimetry was used to investigate the binding abilities of a chiral calix[4]resorcinarene derivative, bearing L-proline subunits, towards a set of suitably selected organic guests. The simultaneous formation of 1:1 and 2:1 host–guest inclusion complexes was observed in several cases, depending on both the charge status of the host and the structure of the guest. Thus, the use of the polarimetric method was thoroughly revisited, in order to keep into account the occurrence of multiple equilibria. Our data indicate that the stability of the host–guest complexes is affected by an interplay between Coulomb interactions, π–π interactions, desolvation effects and entropy-unfavorable conformational dynamic restraints. Polarimetry is confirmed as a very useful and versatile tool for the investigation of supramolecular interactions with chiral hosts, even in complex systems involving multiple equilibria.

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

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–Baylis–Hillman (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.

In this work, we describe the preparation of ten amino acid ionic liquids (AAILs). The AAILs were used as catalysts in a Morita–Baylis–Hillman (MBH) reaction. The MBH adducts were obtained from moderate to good yields and in their racemic form.

Functionalised diimidazolium salts: the anion effect on the catalytic ability

How is it possible to catalyze and simultaneously control the outcome of a reaction? Employing task specific ionic liquids and changing their anions.

Exploring Morita-Baylis-Hillman reactions of p-quinols

The Morita-Baylis-Hillman reaction of p-methylquinols with activated aromatic aldehydes has been studied. Depending on the reaction conditions (solvent and additives), three different products were formed. A mono or double Morita-Baylis-Hillman adduct and a fused 1,3-dioxolane could be obtained in good chemical yields. The use of non-nucleophilic bases to promote the reaction suggested an autocatalytic mechanism.