Catalysts Based on Amino Acids for Asymmetric Reactions in Water

Paradowska, Joanna; Stodulski, Maciej; Młynarski, Jacek

doi:10.1002/anie.200802038

Cited by 225 publications

(75 citation statements)

References 125 publications

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“…As a result, the IL immobilized catalyst is regenerated and can be used for further reactions. Water is known to be the cheapest, environmentally benign, safe and most abundant compound on the earth's surface; and it has attracted a great deal of attention from a green chemistry perspective [33][34][35][36][37][38][39][40][41][42][43]. In addition, water also holds some unique physical and chemical properties, such as high surface tension, hydrogen bonding capability, high dielectric constant and high cohesive energy density [44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Ionic Liquid Immobilized Organocatalysts for Asymmetric Reactions in Aqueous Media

Qiao

Headley

2013

Catalysts

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Ionic liquids are organic salts with melting points typically below ambient or reaction temperature. The unique combination of physical properties of ionic liquids, such as lack of measurable vapor pressure, high thermal and chemical stability, make them ideal to be used as reusable homogenous support for catalysts. In addition, the solubility of ionic liquids in various reaction media can be controlled and easily fine-tuned by modification of the structures of their cations and anions. As a result, ionic liquid immobilized organocatalysts are very effective in aqueous media and can be separated easily from organic solvents, as well as aqueous phases by simply adjusting the polarity of the media. Ionic liquid immobilized organocatalysts are not only very versatile compounds that are effective catalysts for a wide spectrum of reactions, but are also environmentally friendly and recyclable organocatalysts. Herein, we provide a summary of the past decade in the area of asymmetric catalysis in aqueous media for a wide variety of reactions in which ionic liquid and related ammonium salt immobilized organocatalysts are used.

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Section: Introductionmentioning

confidence: 99%

Ionic Liquid Immobilized Organocatalysts for Asymmetric Reactions in Aqueous Media

Qiao

Headley

2013

Catalysts

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“…Both zinc triflate and chiral prolineamides were essential for the catalytic system. In this respect, the combined catalysts could be regarded as mimic of type II aldolase, and an enamine was presumed to be formed in the active site (33)(34)(35)(36)(37)(38).…”

Section: Resultsmentioning

confidence: 99%

The Mimic of Type II Aldolases Chemistry: Asymmetric Synthesis of β‐Hydroxy Ketones by Direct Aldol Reaction

Mei

Han

et al. 2010

Chem Biol Drug Des

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An efficient direct aldol reaction has been developed for the synthesis of chiral b-hydroxy ketone using a combination of C 1 -symmetric chiral prolinamides based on o-phenylenediamine and zinc triflate as catalyst. The reaction was convenient to carry out in aqueous media with up to 98% chemical yields and up to 94% ee values. The current strategy can be regarded as the analogue of aldolase type II, which suggests a new pathway for the designing of new organocatalysts. The development of stereoselective and enantioselective aldol reaction has become an interesting and challenging topic in modern organic and medicinal chemistry (1-3), because the resulting chiral b-hydroxy ketones belong to an extremely important class of biological compounds. In fact, b-hydroxy ketones can serve as versatile building block for the asymmetric synthesis of carbohydrates, amino acids and many other biomolecules (4-6). They also provide privileged structural functionalities that exist in many important natural products (7-12). For example, the b-hydroxy ketones functionalities exist in macrolide classes of antibiotics such as telithromycin and cethromycin which are targeted primarily against Gram-positive bacterial strains including Streptococcus pneumoniae and S. pyogenes, fastidious Gram-negative strains including Haemophilus influenzae and Moraxella catarrhalis, atypicals Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophilia (13). They were also found in conagenin that can improve the antitumor efficacy of adriamycin and mitomycin C against murine leukemias, which suggest its potential utility for cancer chemotherapy (14).In virtue of the importance of chiral b-hydroxy ketones, several approaches aiming to prepare them have been reported in the last decade (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Among all the catalytic direct aldol, the most attractive one is the mimic of the actions of the enzymes. Although the direct catalytic aldol systems which were assumed to proceed through an enamine mechanism by mimic of aldolase type I have been well explored (28-32), the direct aldol systems by using the methods analogue to the actions of aldolase type II containing a zinc cofactor have still remained challenging. In fact, there were only a few reports for direct aldol reactions promoted by the zinc complexes with N-donor ligands in the presence of water until now (33-38). Herein, we reported a chiral ligands and zinc triflate catalyzed asymmetric direct aldol reaction with water as solvent. To our knowledge, this is the first example that mimics type II aldolase utilizing C 1 -symmetric organic molecular based on o-phenylenediamine as chiral ligand. Results and DiscussionsAccording to the mechanism of type II aldolase (33-38), we designed and prepared a series of chiral ligands (Figure 1). These chiral ligands 1-6 were easily prepared from proline and aniline or o-phenylenediamine in high yields. Most of these ligands have C 1 symmetry, expect compound 4, which is a C 2 -symmetric ligand. Then, all thes...

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“…[33][34][35][36][37] Especially, the development of more efficient and sustainable catalysts that are effective in only water has been desired. [38][39][40][41][42] However, the achievement of high reaction efficiency with metal catalysts in water is not easy. To overcome the poor solubility of organic compounds and deleterious effects for metal catalysts in water, ingenious aids such as microwave heating, organic co-solvents, and surfactants are often necessary.…”

Section: Palladium-catalyzed 12-addition Of Organoboronic Acids To Amentioning

confidence: 99%

“…To overcome the poor solubility of organic compounds and deleterious effects for metal catalysts in water, ingenious aids such as microwave heating, organic co-solvents, and surfactants are often necessary. [33][34][35][36][37][38][39][40][41][42] Despite these efforts, reported examples of transition metalcatalyzed arylation of aldehydes with organoboron reagents in only water are quite scarce and have unresolved issues in reaction systems and substrate generality. 43,44) The performance of palladium/thioether-imidazolinium chloride system was examined in the phenylation of 2-naphthaldehyde 7b using water as solvent (Table 4).…”

Section: Palladium-catalyzed 12-addition Of Organoboronic Acids To Amentioning

confidence: 99%

Development of Efficient Catalytic Arylation of Aldehydes with Thioether-Imidazolinium Carbene Ligands

Kuriyama

2012

CHEMICAL & PHARMACEUTICAL BULLETIN

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Effective methods of ligand design have been highly sought due to the significant roles of ligands in controlling metal catalyses. In particular, easy-to-handle ligands to realize high reaction efficacy, substrate tolerance, and environmental friendliness are desirable. Novel bidentate ligands containing N-heterocyclic carbene and thioether moieties were developed based on findings of hemilabile coordination, whose precursors were crystalline solids stable enough to handle and store in the air. The thioether-imidazolinium carbene ligand successfully brought out high catalyst performance of palladium in the catalytic arylation of aldehydes with organoboron reagents, which tolerated a diverse range of substrates including poorly reactive, sterically hindered, and heterocyclic compounds. This process was applied to gram-scale synthesis using only water as solvent with high efficiency and also achieved the effective one-pot synthesis of 3-arylphthalides known as useful biologically active agents and important synthetic intermediates for naturally occurring compounds.

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Catalysts Based on Amino Acids for Asymmetric Reactions in Water

Cited by 225 publications

References 125 publications

Ionic Liquid Immobilized Organocatalysts for Asymmetric Reactions in Aqueous Media

Ionic Liquid Immobilized Organocatalysts for Asymmetric Reactions in Aqueous Media

The Mimic of Type II Aldolases Chemistry: Asymmetric Synthesis of β‐Hydroxy Ketones by Direct Aldol Reaction

Development of Efficient Catalytic Arylation of Aldehydes with Thioether-Imidazolinium Carbene Ligands

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