Preparation Of Chiral Building Blocks Research Articles

Enantioselective synthesis of N-alkylindoles enabled by nickel-catalyzed C-C coupling

Enantioenriched N-alkylindole compounds, in which nitrogen is bound to a stereogenic sp3 carbon, are an important entity of target molecules in the fields of biological, medicinal, and organic chemistry. Despite considerable efforts aimed at inventing methods for stereoselective indole functionalization, straightforward access to a diverse range of chiral N-alkylindoles in an intermolecular catalytic fashion from readily available indole substrates remains an ongoing challenge. In sharp contrast to existing C–N bond-forming strategies, here, we describe a modular nickel-catalyzed C–C coupling protocol that couples a broad array of N-indolyl-substituted alkenes with aryl/alkenyl/alkynyl bromides to produce chiral N-alkylindole adducts in single regioisomeric form, in up to 91% yield and 97% ee. The process is amenable to proceed under mild conditions and exhibit broad scope and high functional group compatibility. Utility is highlighted through late-stage functionalization of natural products and drug molecules, preparation of chiral building blocks.

8 生化学的方法によるキラル合成原料の調製(口頭発表の部)

8 生化学的方法によるキラル合成原料の調製(口頭発表の部)

ChemInform Abstract: Preparation of Chiral Building Blocks for the Enantioselective Total Synthesis of ent‐Kauranoids by the Pig Liver Esterase‐Catalyzed Asymmetric Hydrolysis of a Dialkyl Malonate‐Type Prochiral Diester.

AbstractThe chiral building block (III) is prepared by cyclization of precursor (I) followed by pig liver esterase catalyzed asymmetric hydrolysis of prochiral diester (II).

Preparation of chiral building blocks for the enantioselective total synthesis of ent-kauranoids by the pig liver esterase-catalyzed asymmetric hydrolysis of a dialkyl malonate-type prochiral diester

The preparation of chiral building blocks, suitable for use in the enantioselective total synthesis of kauranoids and ent-kauranoids, is reported herein. The pig liver esterase-catalyzed asymmetric hydrolysis of dimethyl 3,3-dimethyl-2-methylenecyclohexane-1,2-dicarboxylate, a malonate-type prochiral diester, afforded the corresponding half-ester in 96% yield and with 99% enantiomeric excess. The absolute configuration of the half-ester was determined by X-ray crystallographic analysis of its derivative and its enantiodivergent transformations are also described herein.

ChemInform Abstract: A Journey from the Pool of Chiral Synthetic Building Blocks to Cell‐penetrating Peptides, to a Novel Type of Enzyme ‐ and Back.

The roles of polyhydroxy-butyrates/alkanoates (PHB/PHA) in biology, for the preparation of chiral building blocks, and as a source of inspiration for the discovery of β- and γ-peptides are discussed. The syntheses and structures of β-peptides are outlined. The prerequisites for mimicking peptide/protein interactions with β-peptides and two examples are presented. Single terminal β-amino-acid residues can lead to stabilization of peptides (cf. NTS(8-13)) in plasma. Cell-penetrating α-L-, α-D-, mixed α-L/D- and β-oligoarginines (OAs) and -oligoprolines, as well as the mechanism(s) of internalization are compared. Recent studies show that infected erythrocytes, parasitic organisms and mycobacteria are entered by OA-derivatives, which have been employed as transporters of the antibiotic fosmidomycin. While β-peptides are generally enzymatically stable (for days in mammals), a microorganism (S. xenopeptidilytica) with an Ntn enzyme (3-2W4 BapA) was discovered that cleaves only β-peptides, and that was applied in preparations of (enantiopure) β-amino acids and β-peptides.

A Journey from the Pool of Chiral Synthetic Building Blocks to Cell-Penetrating Peptides, to a Novel Type of Enzyme – and back

The roles of polyhydroxy-butyrates/alkanoates (PHB/PHA) in biology, for the preparation of chiral building blocks, and as a source of inspiration for the discovery of β- and γ-peptides are discussed. The syntheses and structures of β-peptides are outlined. The prerequisites for mimicking peptide/protein interactions with β-peptides and two examples are presented. Single terminal β-amino-acid residues can lead to stabilization of peptides (cf. NTS(8-13)) in plasma. Cell-penetrating α-L-, α-D-, mixed α-L/D- and β-oligoarginines (OAs) and -oligoprolines, as well as the mechanism(s) of internalization are compared. Recent studies show that infected erythrocytes, parasitic organisms and mycobacteria are entered by OA-derivatives, which have been employed as transporters of the antibiotic fosmidomycin. While β-peptides are generally enzymatically stable (for days in mammals), a microorganism (S. xenopeptidilytica) with an Ntn enzyme (3-2W4 BapA) was discovered that cleaves only β-peptides, and that was applied in preparations of (enantiopure) β-amino acids and β-peptides.

ChemInform Abstract: Organocatalyzed Enantioselective Desymmetrization of Diols in the Preparation of Chiral Building Blocks

AbstractReview: 49 refs.

Organocatalyzed Enantioselective Desymmetrization of Diols in the Preparation of Chiral Building Blocks

Desymmetrization of diols is a powerful tool to the synthesis of chiral building blocks. Among the different approaches to perform discrimination between both enantiotopic hydroxyl groups, the organocatalytic approach has gained importance in the last years. A diverse range of organocatalysts has been used to efficiently promote this enantioselective transformation and this Minireview examines the different contributions in this field.

Preparation of Chiral Building Blocks via Enantioselective Henry Reaction

Preparation of Chiral Building Blocks via Enantioselective Henry Reaction

Talaromyces flavus and its metabolites

AbstractThis manuscript presents an overview of the research performed on Talaromyces flavus, a microorganism remarkable for its secondary metabolites with unique biological activities, enzymes applicable in the synthesis of saccharides, preparation of chiral building blocks or biotransformations, and for its application in pest biocontrol.

38 キラルビルディングブロックスの触媒的創製とサイアタン類の収束的不斉全合成(口頭発表の部)

38 キラルビルディングブロックスの触媒的創製とサイアタン類の収束的不斉全合成(口頭発表の部)

8‐Oxabicyclo[3.2.1]oct‐6‐en‐3‐ones: Application to the Asymmetric Synthesis of Polyoxygenated Building Blocks

AbstractFor Abstract see ChemInform Abstract in Full Text.

8-Oxabicyclo[3.2.1]oct-6-en-3-ones: application to the asymmetric synthesis of polyoxygenated building blocks.

The development and design of reliable and efficient methods for the construction of chiral building blocks are crucial in modern natural product synthesis. 8-Oxabicyclo[3.2.1]oct-6-en-3-ones are readily accessible scaffolds with defined stereochemical features which have been exploited for non-aldol approaches to the preparation of chiral building blocks. Strategies for their enantioselective synthesis, including asymmetric cycloaddition methods, desymmetrization protocols, and "racemic switch operations", are presented and evaluated.

Optimization of Hydrolase Efficiency in Organic Solvents.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Optimization of hydrolase efficiency in organic solvents.

The application of hydrolases in organic solvents for synthetic purposes is a procedure routinely adopted in organic chemistry, especially for the preparation of chiral building blocks. Numerous studies have shed light on several aspects of the mechanism of hydrolase action in low-water environments. Procedures suitable to improve the catalytic efficiency of enzymes and productivity of the synthetic processes have been reported. These fundamental and applied investigations have made hydrolase-catalyzed reactions in organic solvents of industrial interest. In this article we describe and discuss various approaches adopted to optimize the performance of hydrolases in organic media, with special emphasis on the formulation of the biocatalysts which, under proper conditions, can display an activity equal to that displayed in aqueous buffers.

ChemInform Abstract: Biocatalytic Strategies for the Preparation of Chiral Building Blocks in 100% Chemical and Optical Yield from Racemates

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Enantioselective Synthesis of Dihydropyrans. Catalysis of Hetero Diels−Alder Reactions by Bis(oxazoline) Copper(II) Complexes

C2-symmetric bis(oxazoline)−Cu(II) complexes 1 and 2 catalyze the inverse electron demand hetero Diels−Alder reaction of α,β-unsaturated carbonyl compounds (heterodiene) with electron-rich olefins (heterodienophile) in high diastereo- and enantioselectivity. α,β-Unsaturated acyl phosphonates and β,γ-unsaturated α-keto esters and amides are effective heterodienes, while enol ethers and sulfides function as heterodienophiles. A range of substitution patterns is possible on the heterodiene: terminal alkyl, aryl, alkoxy, and thioether substituents are all tolerated. The enantioselective synthesis of dihydropyrans by this method has been shown to be straightforward: cycloadditions may be conducted with as little as 0.2 mol % of the chiral catalyst and are readily run on multigram scale. The reactions exhibit a favorable temperature−enantioselectivity profile, with selectivities exceeding 90% even at room temperature. A simple reaction protocol that employs a solid air-stable catalyst, convenient reaction temperatures, and low catalyst loadings is described. The utility of the derived cycloadducts in the preparation of chiral building blocks is demonstrated. Models for asymmetric induction are discussed considering product stereochemistry, X-ray crystallographic data for the solid catalysts, and mechanistic studies.

ChemInform Abstract: Preparation of Chiral Building Blocks for a Highly Convergent Vitamin E Synthesis. Systematic Investigations on the Enantioselectivity of the Sharpless Bishydroxylation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Preparation of Chiral Building Blocks for a Highly Convergent Vitamin E Synthesis. Systematic Investigations on the Enantioselectivity of the Sharpless Bishydroxylation

Preparation of Chiral Building Blocks for a Highly Convergent Vitamin E Synthesis. Systematic Investigations on the Enantioselectivity of the Sharpless Bishydroxylation

ChemInform Abstract: Preparation of Chiral Building Blocks for the Synthesis of Aconitium Alkaloids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.