The binding and stabilizing effect of arginine residues in certain aldolases served as inspiring source for the development of a family of amino acylguanidine organocatalysts. Screening and ...optimization led to identify the threonine derivative as the most suitable catalyst for the asymmetric aldol addition of hydroxyacetone, affording the
diastereomer in high ee. In contrast, the proline derivative yielded the
diasteromer. MMFF models suggest the presence of an extensive hydrogen bonding network between the acylguanidinium group and the reaction intermediates.
Asymmetric organocatalysis often operates under near ambient conditions, which means it is air and moisture compatible. However, in many examples water is indeed necessary for achieving excellent ...catalytic results. Ranging from the addition of small amounts of water to a reaction, to complex catalytic systems in the presence of water as the only reaction medium, this review offers an illustrative classification of the uses of water in asymmetric organocatalysis.
This review offers a classification with illustrative examples of the uses and effects of water in asymmetric organocatalysis.
Trichloromethanesulfonyl chloride (CCl3SO2Cl), a commercially available reagent, has been found to perform efficiently in the α-chlorination of aldehydes, including its catalytic asymmetric version, ...under very mild reaction conditions. Under our reaction conditions, this compound outperforms typical chlorinating reagents for organic synthesis, facilitates workup and purification of the product, and minimizes the formation of toxic, chlorinated organic waste.
A new tris(1-benzyl-1H-1,2,3-triazol-4-yl)methanol ligand 3 has been prepared by a triple Cu(I)-catalyzed alkyne−azide 1,3-dipolar cycloaddition (CuAAC). Ligand 3 forms a stable complex with CuCl, ...which catalyzes the Huisgen 1,3-dipolar cycloaddition on water or under neat conditions. Low catalyst loadings, short reaction times at room temperature, and compatibility with free amino groups make 3·CuCl an outstanding catalyst for CuAAC.
The development of a highly efficient, polymer-supported organocatalyst for the Michael addition of ketones to nitroolefins is described. A 1,2,3-triazole ring, constructed through a click ...1,3-cycloaddition, plays the double role of grafting the chiral pyrrolidine monomer onto the polystyrene backbone and of providing a structural element, complementary to pyrrolidine, key to high catalytic activity and enantioselectivity. Optimal operation in water and full recyclability make the triazole linker attractive for the immobilization of organocatalysts.
The study of novel metal-templated dynamic organocatalytic systems has led to the identification of CuSO
as the most efficient template to assemble monofunctional prolinamide- and thiourea-modified ...pyridine ligands. The structural and electronic requirements to assemble an efficient catalyst have been disclosed: both pyridine ligands must bear a 1,3-substitution pattern, and the thiourea ligand serves as a reducing agent to copper(i) as well. Eventually, the cooperative effects achieved with such a simple system deliver high reaction rates and stereoselectivities at room temperature in the asymmetric aldol reaction, requiring only 1 mol% of copper salt.
Faster than believed: Transmetalation from aryl boronic acids and triaryl boroxines to diethylzinc takes place within minutes following a two‐step, low‐energy pathway (see picture), according to ...density functional calculations and reaction microcalorimetry measurements. The experimental conditions for a practical, atom‐economical, and highly enantioselective catalytic arylation of a variety of aldehydes have been developed from these data.
Desulfitative Thioalkylation of Alkenes Cao, Lidong; Jimeno, Ciril; Renaud, Philippe
Advanced synthesis & catalysis,
September 8, 2020, Letnik:
362, Številka:
17
Journal Article
Recenzirano
Odprti dostop
An efficient method for the thioalkylation of alkenes via radical desulfitative sulfur‐group transfer is described. The reaction is based on the use of readily available thiosulfonates as starting ...materials and cheap radical initiators such as dilauroyl peroxide (DLP) and sun lamp irradiation. No transition metal catalyst is required, and the reaction takes place under mild conditions.
A zinc(II)‐templated catalyst assembling terpyridine and bipyridine organocatalytic ligands has been developed for the asymmetric aldol reaction. The system has been optimized to maximize the ...formation of the heteromeric bifunctional species through the determination of the equilibrium constants leading to the formation of all the species present. A practical, easy to synthesize catalytic system providing high stereoselectivity has been achieved in this way.
A ready to synthesize bis(prolinamide)terpyridine ligand self‐assembles with zinc(II) and a a hydrogen bond donor ligand to furnish a highly active catalyst for the asymmetric aldol reaction.
The structural optimization of a family of modular, enantiopure β-amino alcohol ligands with a common 2-amino-2-aryl-1,1-diphenylethanol skeleton, whose stereogenicity was introduced through the ...Jacobsen epoxidation of 1,1-diphenyl-2-arylethylenes, has led to the identification of a small set of optimal catalysts with enhanced activity and enantioselectivity in the addition of alkylzinc and arylzinc reagents to aldehydes. Criteria for the discrimination between apparently analogous, highly enantioselective ligands are proposed.
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