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The synthesis and characterization of N,N′-diethyl (L-Et,Et) and N-ethyl,N′-methyl (L-Et,Me) glyoxal-bridged cyclam ligands are described, together with the X-ray crystal structure of the complex [MnCl2(L-Et,Me)]. Bleaching of morine in the presence of hydrogen peroxide by the corresponding Mn catalysts [MnCl2(L-Et,Et)], [MnCl2(L-Et,Me)] and [MnCl2(L-Me,Me)] has been studied in aqueous solution at three different pH values (8.0, 8.75, and 9.0). The results clearly show that increasing pH has a different effect on the three catalysts, and that the dimethyl derivative is by far the most active.

This review deals with the solution given by synthetic chemists to overcome the problem of access to both enantiomers of a given process when carbohydrates are used as ligands. Indeed, although sugars are stereochemically rich compounds, and derived from one of the most abundant renewable material, their use in asymmetric catalysis has been limited by the fact that most of them have D-configuration. This review explains the concept of pseudo-enantiomeric ligands, and collects examples based on pyranoses, by describing their relevant use in asymmetric catalysis.

It is described the simple design of a series of N,N′,O,O′-chiral ligands (elpaN-salen-H2), which represent a subset of the elpaN-type library of ligands based on β-1,2- d -glucodiamine. The corresponding Mn(III) complexes were examined in the asymmetric epoxidation of styrenes with satisfactory results, e.g. cis-β-methylstyrene was functionalised in ees up to 88%.

A homogeneous supported catalyst based on Zn(II) was prepared by anchoring complex [Zn(OAc) 2 (N,N′-chelate)] on silica, where N,N′-chelate is a suitably functionalised di-imine ligand. The complex was able to promote the esterification and transesterification of acidic vegetable oils at 160 °C within two hours. The catalyst could be also easily recovered and immediately re-cycled.

This study aimed to optimize the zinc-catalyzed trans-esterification, and pointed to assess the effect of the solvent, the catalyst, its loading and the nature of the substrate. The screening disclosed the remarkable ability of zinc(II) acetate to promote the reaction in refluxing toluene at low catalyst loading. A significant improvement ensued with respect to recently results on the same reactions, in terms of less restrictive conditions and more convenient catalyst precursors.

New zinc(II) compounds containing functionalized Schiff bases have been prepared and characterized. The complexes catalyze the transesterification of soybean oil in mild conditions, and their activity can be modulated by a fine selection of the anions and/or of the substituents on the ancillary bidentate ligand. The compounds are active in the esterification of fatty acids and could therefore also be used to produce biodiesel from waste oils.

The elpaN-Py family of ligands, which represents a subset of the elpaN-type library based on d-glucose, is described. The ligands are structural analogs of the privileged bis(pyridine-2-carboxamides) derived from trans-1,2-diaminocyclohexane, and differ for the type of substitution in the coordinating functions present in positions 1 and 2. Their ability to induce high enantioselectivity in asymmetric allylic alkylations promoted by molybdenum under microwave irradiation has been successfully demonstrated, starting from both a linear (ee up to 99%) and a branched substrate (ee up to 96%). The multifunctional nature of the sugar scaffold was exploited for the preparation of a polar ligand, through deprotection of the hydroxyl groups in positions 3, 4 and 6. In this version, it was possible to verify the performance in catalysis in alternative solvents, such as ionic liquids and water.

A series of glucopyranoside phosphite–pyridine ligands have been applied in the metal-catalyzed allylic substitution and conjugate 1,4-addition reactions of several substrate types. We have been able to identify ligands that provided promising enantioselectivities in the Pd-catalyzed intermolecular allylic substitution of cyclic substrates (ee’s up to 86%) and desymmetrization (ee’s up to 94%) and in the Cu-catalyzed conjugate addition of challenging aliphatic enones (ee’s up to 90%).

This paper demonstrates the versatility of the class of chiral ligands naplephos, which has been further refined by preparing new ‘tagged’ versions for selective use in polar media (e.g., ionic liquids). These modified types, along with the best performing original varieties, have been examined in two Pd-catalysed asymmetric processes involving C–C and C–N bond formation. High ees have been achieved in traditional solvents, while the experiments performed in ionic liquids confirm the difficulty of predicting the outcome of a reaction in these media and the general decrease in the catalytic performance.