Chiral bispyridylamide metal complexes as catalysts for the enantioselective addition of TMSCN to aldehydes

In the Arena of Enantioselective Synthesis, Titanium Complexes Wear the Laurel Wreath

“…392 Compound 290 is a tetradentated ligand with two acidic protons and two coordinating nitrogen atoms, such as in salen ligands 268. In this case, a complete study of all parameters affecting the reaction was performed, 393 including solvent, relative amount of titanium tetraisopropoxide (3a), and reagent concentration. The relative amount of the catalyst and initial concentration of aldehyde had a clear effect on the results, with dilution decreasing the enantioselectivity.…”

Isostructural Mercury Coordination Polymers with Amide Junction: Interplay of Coordination and π–π Stacking

“…A few related compounds in the literature are discussed below. Compound [Zr(L 2‑py )(O t Bu) 2 ] shows a discrete monomeric six-coordinated Zr complex in which the amide ligand acts as a four-dentate dianion ligand (L 2‑py = N , N′ -bis(2-pyridinecarboxamido)-1,2-diphenylethane). Two other coordination sites are occupied by monodentate O t Bu anions.…”

“…In recent years, coordination polymers with organic ligands based on two pyridine moieties as coordination sites and different spacers such as alkyl chain, imine bond, and amide functionality have been designed. − Considering these bispyridyl ligands with amide junction reveals that (1) two pyridyl groups are a good choice for connecting metal centers, (2) the amide group may participate in the binding to metal through the oxygen atom of carbonyl moiety, , (3) π–π stacking between pyridine rings and also the hydrogen bonding of amide functionality can add extra dimensionality to the resulted structure, , and (4) due to the low rotational barrier of the amide group, these ligands can possess rotational flexibility and adopt a variety of conformations. , In this regard, reports on the coordination compounds of N , N′ -(1,2-diphenylethane-1,2-diyl)dipyridineamide ligands are rare, with the exception of Moberg and co-workers (monomeric Zr complex), Zhou and co-workers (monomeric Ni complex), and Williams and co-workers (polymeric Cu complex) reports containing the N , N′ -(1,2-diphenylethane-1,2-diyl)dipicolinamide ligand.…”

Enantioenriched Acylated Cyanohydrins: Synthesis and Analysis

“…29 This type of ligand had proven to be successful for molybdenum-catalyzed allylations in particular, 30 and also for other Lewis acid catalyzed processes, such as ring opening of meso-epoxides 31 and silylcyanation of aldehydes. 32 The addition of a cyanoformate resulted, however, in poor enantioselectivity, and acetyl cyanide was unreactive. 33 Salen-based catalysts had been shown to provide superior results in the additions of ethyl cyanoformate.…”