Applications of Carbohydrate‐Based Organocatalysts in Enantioselective Synthesis

Abstract

Carbohydrates have been widely used for stereochemical control, either as chiral auxiliaries or as ligands. Their natural abundance and rigidity of structure, together with the presence of many functional groups, have also in recent years made them attractive chiral modular units for the assembly of bifunctional organocatalysts. Applications have ranged from the more complex bifunctional carbohydrate‐based amine–(thio)ureas and prolinamides to simple amino alcohols. The presence of many hydroxy groups and their consequent water solubility has allowed for the study of reactions in aqueous media. Nowadays they have been applied to many reactions such as the aldol, Michael, Stetter, Biginelli, Morita–Baylis–Hillman, decarboxylative Mannich and other reactions, and even to the multistep synthesis of known drugs. This review provides an overview of developments in this field in the period from 2009 to mid‐2014.

Glucose‐coated superparamagnetic nanoparticle‐catalysed pyrazole synthesis in water

“…Glucose is the most important monosaccharide in living organisms and it is known as the human body's key source of energy, so it can be considered as a natural, biocompatible agent. As a consequence of the polyhydroxyl structure, it has been used as a green catalyst and provided excellent catalytic activity in chemical reactions such as epoxidation and enantioselective Michael addition . Also, it has played the role of a green medium for undertaking reactions .…”

Non-Covalent Interactions in Enantioselective Organocatalysis: Theoretical and Mechanistic Studies of Reactions Mediated by Dual H-Bond Donors, Bifunctional Squaramides, Thioureas and Related Catalysts

“…In recent years carbohydrates have been used more frequently as chiral modular units for bifunctional organocatalysts [30]. In 2016 Khan, Narula and coworkers developed thiourea-based catalysts incorporating D-glucose as a core unit and tested them on the addition of ketones to nitroalkenes.…”

“…An enantioselective organocatalytic conjugate addition of α,β-unsaturated ketones 29, promoted by a bifunctional organocatalyst, cinchona-squaramide C17, was described by Fernández-Salas, Alemán and coworkers in 2019 (Figure 23) [52]. The attractiveness of this method lies in its environmentally friendly nature since employing TMSN 3 (30) as a nucleophile avoids the use or preformation of hydrazoic acid, a dangerous and highly explosive substance. No acidic additives were required either.…”

Valorization of Waste: Sustainable Organocatalysts from Renewable Resources

“…[97] It is the leadingp layer in the field of aminosugar-based organocatalysis;s everala pplications of d-glucosamine-derivedo rganocatalysts were recently reported in asymmetrico rganic synthesis. [92] In 2017, Monge et al reportedt he synthesis of anovel series of peracylated glycosamine-derived organocatalysts in the enantioselective nucleophilic addition of formaldehyde tert-butylhydrazone 25 to aliphatic a-ketoesters 43 (Scheme 31). [98] Peracetylated b-d-glucosamine thiourea 44 allowed the isolation of aliphatic tertiary azomethyl alcohols 45 with high yields and moderate enantioselectivities.…”