Synthesis of novel carbohydrate-based valine-derived formamide organocatalysts by CuAAC click chemistry and their application in asymmetric reduction of imines with trichlorosilane

Synthesis of Anticoagulant Pentasaccharide Fondaparinux via 3,5-Dimethyl-4-(2'-phenylethynylphenyl)phenyl Glycosides

Here, we disclosed a convenient procedure for the preparation of EPP [3,5-dimethyl-4-(2'-phenylethynylphenyl)phenyl] glycosides and their application to an effective synthesis of fondaparinux, the clinically approved anticoagulant heparin pentasaccharide. The use of EPP glycosides in the one-pot orthogonal glycosylation for the synthesis of heparin-like tetrasaccharides has also been achieved.

Synthesis and Applications of Carbohydrate-Based Organocatalysts

Organocatalysis is a very useful tool for the asymmetric synthesis of biologically or pharmacologically active compounds because it avoids the use of noxious metals, which are difficult to eliminate from the target products. Moreover, in many cases, the organocatalysed reactions can be performed in benign solvents and do not require anhydrous conditions. It is well-known that most of the above-mentioned reactions are promoted by a simple aminoacid, l-proline, or, to a lesser extent, by the more complex cinchona alkaloids. However, during the past three decades, other enantiopure natural compounds, the carbohydrates, have been employed as organocatalysts. In the present exhaustive review, the detailed preparation of all the sugar-based organocatalysts as well as their catalytic properties are described.

Rational Design of Simple Organocatalysts for the HSiCl3 Enantioselective Reduction of (E)-N-(1-Phenylethylidene)aniline

Prolinamides are well-known organocatalysts for the HSiCl3 reduction of imines; however, custom design of catalysts is based on trial-and-error experiments. In this work, we have used a combination of computational calculations and experimental work, including kinetic analyses, to properly understand this process and to design optimized catalysts for the benchmark (E)-N-(1-phenylethylidene)aniline. The best results have been obtained with the amide derived from 4-methoxyaniline and the N-pivaloyl protected proline, for which the catalyzed process is almost 600 times faster than the uncatalyzed one. Mechanistic studies reveal that the formation of the component supramolecular complex catalyst-HSiCl3-substrate, involving hydrogen bonding breaking and costly conformational changes in the prolinamide, is an important step in the overall process.

Recent advances in reactions promoted by amino acids and oligopeptides

During the last 20 years, Organocatalysis has become one of the major fields of Catalysis. Herein, we provide a recent overview on reactions where the use of amino acids and peptides as the organocatalysts was employed. All aspects regarding aldol reactions, Michael reactions, epoxidation, Henry reactions and many others that are crucial for the reaction conditions and reaction mechanisms are discussed.

Combined experimental/theoretical study of d-glucosamine promoted Ullmann-type C–N coupling catalyzed by copper(i): does amino really count?

Ullmann type C–N coupling reaction catalyzed by copper(i) with d-glucosamine derivatives as promoters was studied by means of combined experimental/theoretical investigation.

One-pot synthesis of new triazole-sucrose derivatives via click chemistry and evaluation of their antitubercular activity

Readily prepared copper nanoparticles are an effective catalyst for 1,3-dipolar cycloaddition of carbohydrate azide and a variety of alkynes that furnishes the corresponding 1,2,3-triazole-sucrose derivatives in excellent yields. Products were screened for their antimycobacterial activity against

Efficient Ullmann C–N coupling catalyzed by a recoverable oligose-supported copper complex

The recoverable oligose-supported copper complex as catalyst for an Ullmann-type C–N coupling reaction of N-nucleophiles and aryl halides under mild conditions.

Asymmetric reduction of imines with trichlorosilane catalyzed by valine-derived formamide immobilized onto magnetic nano-Fe3O4

Magnetic nano-Fe₃O₄-supported organocatalysts were synthesized by anchoring valine-derived formamide onto the surface of Fe₃O₄ magnetic nanoparticles, which were applied in the asymmetric reduction of imines with trichlorosilane.