Carbohydrates as enantioinduction components in stereoselective catalysis

Abstract

In this review, synthetic approaches to carbohydrate-based ligands and catalysts are outlined, along with example applications in enantioselective catalysis.

Discrimination of chiral copper(ii) complexes upon binding of galactonoamidine ligands

“…16,17 More details and additional reports including complex formation between carbohydrates and transition metal or lanthanide ions may be found elsewhere. 11,[18][19][20][21][22][23][24][25][26][27][28][29][30] In this context, we disclose here for the first time a study to evaluate the coordination between a putative transition state analog of the glycoside hydrolysis and metal complexes. The assemblies are characterized by spectrophotometric titrations, isothermal titration calorimetry, CD spectroscopy and DFT methods.…”

Studies on the influence of saccharide fragment of urea organocatalysts on the yield and enantioselectivity of aza-Henry reaction

“…Another group of urea organocatalysts, the activity of which we examined in the aza-Henry reaction, were mono-and disaccharide derivatives containing the proline ring as a second scaffold (Table 1, entries 11-21). In the series of the monosaccharide catalysts L6-L8, the best of the sugar has proven to be glucose derivative L8, with the isopropyl protecting groups: 82% yield and 75% ee in THF (Table 1, entries [15][16]. In contrast, the melibiose derivative L9 proved to be less active and resulted in a reaction product in 53% yield and 64% ee.…”

Carbohydrate-functionalized N-heterocyclic carbene Ru(ii) complexes: synthesis, characterization and catalytic transfer hydrogenation activity

“…Since the triazolylidene ligand is robustly coordinated to the ruthenium center, transfer hydrogenation allows for evaluating the asymmetric induction of the stereochemically welldefined carbohydrate functionality by using prochiral ketones. Similar carbohydrate-based ligands have previously been shown to be effective in asymmetric catalysis, 58,62,[72][73][74][75] including hydrosilylation of ketones. 62 The enantioselectivity of 5Glc was probed with acetophenone as prochiral substrate for transfer hydrogenation (entry 6).…”

“…Several complexes with carbohydrate-based phosphine and phosphinite ligand scaffolds have shown excellent performance in asymmetric catalysis. [56][57][58] Similar work with N-heterocyclic carbene ligands, however, is much more scarce. 59,60 In pioneering work, Dyson and co-workers investigated the anticancer activity of Ru complexes of carbohydrate-functionalized NHC ligands, 60,61 though only few examples have explored the catalytic activity of such carbohydrate-NHC hybrid complexes.…”