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

Abstract

Triazolylidene NHCs decorated with a carbohydrate wingtip group were complexed to a ruthenium(ii) center. Deprotection of the carbohydrate in the metal complex affords a carbohydrate–NHC hybrid system for use as a transfer hydrogenation catalyst.

Anion–cation synergistic metal-free catalytic oxidative homocoupling of benzylamines by triazolium iodide salts

“…25 Molten ionic liquids like (NBu 4 )Br have also recently been reported to mediate this transformation, when used as a solvent. 26 Based on our interest in triazolium salts as ligand precursors to 1,2,3-triazolylidene complexes, [27][28][29][30][31] and inspired by the activity of some of the ionic liquids for amine homocoupling, 32 we decided to investigate the possibility for these organic salts to act as molecular catalysts for oxidative amine coupling. An attractive feature of triazolium salts is their versatility for incor-porating (functionalized) substituents, since triazole precursors are conveniently prepared through Cu(I)-catalyzed azidealkyne cycloaddition chemistry.…”

Heteroleptic 1,4‐Diazabutadiene Complexes of Ruthenium: Synthesis, Characterization and Utilization in Catalytic Transfer Hydrogenation

“…The catalytic efficiency of our complexes in transfer hydrogenation of aldehydes and ketones is better than many of the reported ruthenium‐catalysts. [ 1b,1e,2a,2c,2h,2i,20b,20c ] For comparison of the catalytic efficiency of our complexes, we prepared the well‐known [Ru(trpy)(bpy)Cl]ClO 4 complex and tested it as catalyst precursor (0.00002 mol‐%) under the same experimental condition for the transfer hydrogenation of 4‐chlorobenzaldehyde. The expected reduced product, viz.…”

“…Hydrogenation of substrates is a key step in many organic transformations. Though addition of molecular hydrogen has always been there as a familiar protocol, transfer hydrogenation has gradually emerged as a favorite alternative for many such reductions, [ 1–6 ] primarily owing to the convenience associated with this method. Several transition metal complexes are reported to catalyze transfer hydrogenation reactions.…”

Cu(I)-Catalyzed Click Chemistry in Glycoscience and Their Diverse Applications

“…Considering this fact, Albrecht and co-workers very recently reported a facile click-inspired synthesis of carbohydrate-containing ruthenium complexes as N -heterocyclic carbene (NHC) glycohybrids (Scheme ). Reported ligands were composed of glycosyl (either glucosyl or galactosyl sugar) and click-inspired triazole linked via ethylene spacer. Glucose and galactose derived NHC ligands ( 1741a , b ) were subjected to deacetylation using KOH in propanol/H 2 O to produce a stable Ru complex that can be stored in solution over several hours, while it is unstable in the solid state.…”