Enantioselective Hydrolysis of α-Amino Acid Ester by Chiral Metallomicelles

Metall0ndcellesmadeup0ffunctionalizedsurfactants(orliP0philicligands)caPable0feffectivechelationofmetalionsarecurrentlyreceivingc0nsiderableinterestbecauseoftheircatalyticabilitytomindcmetall0enzymes.OfpatticularinterestarethendcellarmodelsofhydrolghcmetalloenZyInes,whichareabletoprom0tethecleavageofphosphoricandcarboxylicesters0raAndes.'-'M0stofthemaref0cused0ntheligandscontainingidridazole',pyridine'orl,lO-phenanthroline'asthebasicchelatingsubunitandasthem0lecularjunctionfortheparaffmiccha…     

Separation and Structure of Chiral S—Malic Acid Hydrate

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍｅｔｈｏｄｏｆｓｅｐａｒａｔｉｎｇａｒａｃｅｍｉｃｍｉｘｔｕｒｅｉｎｔｏｉｔｓｅｎａｎｔｉｏｍｅｒｓｔｈｒｏｕｇｈｔｈｅｆｏｒｍａｔｉｏｎｏｆｄｉａｓｔｅｒｅｏｍｅｒｉｃｍｏｌｅｃｕｌａｒｃｏｍｐｌｅｘｂｙｒｅａｃｔｉｏｎｗｉｔｈａｎｏｐｔｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｈａｓｂｅｅｎｗｉｄｅｌｙｉｎｖｅｓｔｉｇａｔｅｄ .Ｆｒｏｍｔｈｅｐｏｉｎｔｏｆｖｉｅｗｏｆｃｒｙｓｔａｌｌｏｇｒａｐｈｙ ,ａｎｅｓｓｅｎｔｉａｌｐｒｅｒｅｑｕｉｓｉｔｅｏｆｔｈｅｓｕｃｃ…     

Chiral Phosphoric Acid Creates Promising Opportunities for Enantioselective Photoredox Catalysis

In recent years,visible light driven enantioselective chemical transformations have emerged as new additions to the toolkit of synthetic chemists to accomplish more efficient assembly of chiral molecules.Nonetheless,implementing precise stereocontrol on photoinduced intermolecular radical coupling process remai ns arduous.     

Molecular Recognition of Chiral Zinc Porphyrin with Amino Acid Esters

One kind of novel chiral porphyrin and its zinc complex were synthesized and characterized. The molecular recognition of chiral zinc porphyrin towards amino acid esters in CHCl₃ was investigated by UV‐vis spectral titration method. The associative constants of the molecular recognition reactions were all K_D>K_L and followed the order of K(PheOMe)>K(LeuOMe)>K(ValOMe)>K(AlaOMe) in host (Zn(L‐BocTyr)TAPP). Circular dichroism spectra were used to explain chiral molecular recognition. The minimal energy conformation of host‐guest molecular system was sought by molecular dynamics method. The molecular recognition process of this host‐guest system was calculated by quantum chemistry and the results were explained by the experiments     

Design and Synthesis of Chiral Molecular Tweezers Based on Deoxycholic Acid

Molecular tweezers is a novel type of artificial receptors, which not only offer the advantage of efficient construction but also their surfaces can be tailored for specific applications. The clefts of molecular tweezers are particularly effective in regard to complementarity with substrates since functional groups attached to the interior of the cleft converge on substrates held inside1. So, in recent years, the molecular tweezers receptors have attracted more and more attention in molecular …     

Chiral Phosphoric Acid Catalyzed Atroposelective C−H Amination of Arenes

N-arylcarbazole structures are important because of their prevalence in natural products and functional OLED materials. C−H amination of arenes has been widely recognized as the most efficient approach to access these structures. Conventional strategies involving transition-metal catalysts suffer from confined substrate generality and the requirement of exogenous oxidants. Organocatalytic enantioselective C–N chiral axis construction remains elusive. Presented here is the first organocatalytic strategy for the synthesis of novel axially chiral N-arylcarbazole frameworks by the assembly of azonaphthalenes and carbazoles. This reaction accommodates broad substrate scope and gives atropisomeric N-arylcarbazoles in good yields with excellent enantiocontrol. This approach not only offers an alternative to metal-catalyzed C–N cross-coupling, but also brings about opportunities for the exploitation of structurally diverse N-aryl atropisomers and OLED materials.     

Enantioselective Redox-Divergent Chiral Phosphoric Acid Catalyzed Quinone Diels–Alder Reactions

An efficient enantioselective construction of tetrahydronaphthalene-1,4-diones as well as dihydronaphthalene-1,4-diols by a chiral phosphoric acid catalyzed quinone Diels–Alder reaction with dienecarbamates is reported. The nature of the protecting group on the diene is key to the success of achieving high enantioselectivity. The divergent “redox” selectivity is controlled by using an adequate amount of quinones. Reversible redox switching without erosion of enantioselectivity was possible from individual redox isomers.     

Synthesis and Enantioselective Discrimination of Chiral Fluorescence Receptors Bearing Amino Acid Units

Two chiral fluorescence receptors （1, 2） were synthesized, and their structures were characterized by IR, ^1H NMR, ^13C NMR, mass spectra and elemental analysis. The chiral recognition of receptors was studied by ^1H NMR and fluorescence spectra. The results demonstrate that receptors and dibenzoyl tartrate anion formed a 1 ： 1 complex. The receptor 1 exhibited a good enantioselective recognition ability toward the enantiomers of dibenzoyl tartrate anion.     

Chiral Phosphoric Acid Catalyzed Asymmetric Friedel–Crafts Alkylation of Indoles with Nitroolefins

Abstract

Asymmetric Michael-type Friedel–Crafts (F–C) alkylations of indoles with nitroolefins catalyzed by a chiral H₈-BINOL-based phosphoric acid were investigated. The reactions took place very smoothly in the presence of only 5 mol-% of catalyst at room temperature to afford the desired F–C alkylation products in good yields and with moderate enantioselectivities.

GRAPHICAL ABSTRACT      

Syntheses of Chiral Calix [4] arene Derivatives Bearing Amino Acid Residue

The syntheses of chirai calix[4]arene derivatives bearing amino acid residue at the lower rim or upper rim by three different methods were reported.     

Chiral Vinyl Sulfoxides as Useful Reagents for the Synthesis of β-Amino Acid Derivatives

(S)- and (R)-β-amino acid derivatives were synthesized by the asymmetric conjugate addition of ammonia and piperidazine to t-butyl (E)-2-[(R)- and (S)-p-tolylsulfinyl]cinnamates, respectively.     

Study on Bicoordination Chiral Inducement Catalysis of （R）-4-Thiazolidinecarboxylic Acid

The bicoordination chiral inducement catalysis of (R)-4-thiazolidinecarboxylic acid in the enantioselective borane reduction of prochiral ketones has been studied. The fact that the absolute configuration of the main product can be changed by simply using different operation methods was firstly verified. And the reason of bicoordination chiral inducement was discussed.     

Enantioselective Alkynylation of Benzaldehyde Catalyzed by New Chiral Lewis Acid Ligand: Zinc-Amide Complex

The enantioselective alkynylzinc addition to aldehydes is very useful for the synthesis of chiral propargyl alcohols which are important versatile building blocks of many biologically active compounds and natural products1. A series of chiral oxazolidines were conveniently synthesized from amino acids in three steps with good yields. The use of chiral Lewis acid ligand: zinc-amide complex in situ generated from this oxazolidine with alkylzinc as chiral catalysts for the enantioselective alkyny…     

On Chiral Space Groups and Chiral Molecules

Aschemicalnomenclaturewasoriginallydevelopedforcompoundsinthesolutionstate,thereissomeconfusionintheproperuseoftheterm慶hiralfordescribingcertaincrystalstructures.Thishasledtoanumberofcompoundsbeingincorrectlycategorizedasbeingchiralalthoughtheybelongtocentrosymmetricspacegroupsorthosehavingmirrorplanes.Achiralcompoundthatseparatesfromsolutionasacrystallinematerialmustnecessarilypackinamotifsuchthatothermoleculesintheunitcellarenotsuperimposableontheirownmirrorimages.Theconditionforopticalacti…     

Kinetic Resolution of Azaarylethynyl Tertiary Alcohols by Chiral Brønsted Acid Catalysed Phosphine-Mediated Deoxygenation

A chiral Brønsted acid catalysed phosphine-mediated deoxygenation protocol is reported. This metal-free method provides a precise kinetic resolution platform for azaarylethynyl tertiary alcohols, which are a broad category of biologically and synthetically important azaarene derivatives. In addition to providing an efficient method for the first asymmetric preparation of these tertiary alcohols, the strategy facilitates the construction of azaaryl-functionalized allenes with good to excellent enantioselectivities. The high selectivity factors (s up to 235), broad substrate scope, and ability to convert azaaryl compounds into both chiral tertiary alcohols and allenes robustly underscore the efficiency and promising utility of this method. The practicability is further validated by the successful synthesis of deuterated allenes with high ee values and substantial incorporation of deuterium using inexpensive D₂O as the deuterium source.     

Synthesis of Novel Chiral Macrocyclic Polyamides Derived from L‐/D‐Tartaric Acid

A convenient and efficient synthesis of chiral macrocyclic polyamides derived from L‐/D‐tartaric acid is reported. These chiral compounds could not only be used for chiral recognition, but also provide a feasible way to synthesize chiral macrocycles.     

Synthesis of a Novel Chiral Trihydroxamic Acid Containing L-Pro-L-Ala-L-Ala-β-(HO)Ala-OMe Unit

Iron is indispensable for almost all life forms1. Under iron-deficient environments, microorganisms secrete siderophores to chelate ferric ions and then, transport ferric ions into cells by specific receptor recognitions2,3. Siderophores have many clinica…     

Synthesis of Two New Chiral Blocks for the Construction of Peptide Nucleic Acid (PNA)

AnewtypeofDNAmimictermedPNA(PeptideNtlcleicAcid).wasfirstpreparedbyNielsenela/'intileearly1990s.ItisanoligonucleotideanalogueinwhichtheentiredeoxyribosephosphatebackbonehasbeenreplacedbyachemicallycompletelydilTerent.butstructurallyhomomorphousachira...     

Synthesis of a Novel Chiral Trihydroxamic Acid Containing L-Pro-L-AIa-L-AIa-β-（HO）AIa-OMe Unit

An N-hydroxyl peptide unit of H-L-Pro-L-Ala-L-Ala-β-（BnO）Ala-OMe was synthesized by stepwise chain building method in solution. Then, based on nitrilotriacetic acid backbone and this N-hydroxyl peptide unit, a novel chiral tripodal ligand P as an analogue of desferrichrome, has been synthesized. In neutral pH, ligand P formed stable tri（hydroxamato）- iron（Ⅲ） complexes which showed a maximum absorptiota （∑max=2750 M^-lcm^-1） at 422 nm in UV-Vis spectra. The characteristic absorption spectra are similar to those of natural trihydroxamate-type siderophores.