12 results match your criteria Asian Journal of Organic Chemistry[Journal]

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A Redox Auxiliary Strategy for Pyrrolidine Synthesis via Photocatalytic [3+2] Cycloaddition.

Asian J Org Chem 2019 Jul 21;8(7):978-985. Epub 2019 Mar 21.

Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.

Cycloaddition reactions can be used to efficiently assemble pyrrolidine rings that are significant in a variety of chemical and biological applications. We have developed a method for the formal cycloaddition of cyclopropyl ketones with hydrazones that utlizes photoredox catalysis to enable the synthesis of a range of structurally diverse pyrrolidine rings. The key insight enabling the scope of photoredox [3+2] cycloadditions to be expanded to C=N electrophiles was the use of a redox auxiliary strategy that allowed for photoreductive activation of the cyclopropyl ketone without the need for an exogenous tertiary amine co-reductant. Read More

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Recent Developments in Stereoselective Chemical Glycosylation.

Asian J Org Chem 2019 Jun 2;8(6):802-813. Epub 2019 May 2.

Department of Chemistry, Tufts University, 62 Talbot Ave., Medford, MA 02155, USA.

Because of their pivotal biological functions, attention to sugars and glycobiology has grown rapidly in recent decades, leading to increased demand for homogeneous oligosaccharides. The stereoselective preparation of oligosaccharides by chemical means remains challenging and continues to be a vivid research area for organic chemists. In the past decade, new approaches and reinvestigated traditional methods have transformed the field. Read More

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Ammonium Ylide Mediated Cyclization Reactions.

Asian J Org Chem 2018 May 25;7(5):852-864. Epub 2018 Mar 25.

Institute of Organic Chemistry, Johannes Kepler University Linz Altenbergerstr. 69 4040 Linz (Austria).

The use of readily accessible ammonium ylides for (asymmetric) transformations, especially cyclization reactions, has received considerable attention over the past two decades. A variety of highly enantioselective protocols to facilitate annulation reactions have recently been introduced as an alternative to other common methods including S-ylide-mediated strategies. It is the intention of this short review to provide an introduction to this field by highlighting the potential of ammonium ylides for (asymmetric) cyclization reactions as well as to present the limitations and challenges of these methods. Read More

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Syntheses of Highly Functionalized Spirocyclohexenes by Formal [4+2] Annulation of Arylidene Azlactones with Allenoates.

Asian J Org Chem 2018 Aug 4;7(8):1620-1625. Epub 2018 May 4.

Johannes Kepler University Linz, Institute of Organic Chemistry, Altenbergerstrasse 69, 4040 Linz (Austria).

A straightforward phosphine-catalyzed formal [4+2] annulation between α-branched allenoates and arylidene azlactones has been developed to access highly functionalized spirocyclohexenes. This cyclization favors the γ-addition of the phosphine-activated allenoates over a β'-addition pathway. Detailed computational studies support the proposed mechanism and provide a reasonable explanation for the observed regioselectivity and the noted effect of the catalyst. Read More

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Nature Inspired Molecular Design: Stereoselective Synthesis of Bicyclic and Polycyclic Ethers for Potent HIV-1 Protease Inhibitors.

Asian J Org Chem 2018 Aug 8;7(8):1448-1466. Epub 2018 Jun 8.

Department of Chemistry and Department of Medicinal Chemistry, Purdue University, West Lafayette, Indiana 47907 (USA).

We have developed a conceptually new generation of non-peptidic HIV-1 protease inhibitors incorporating novel structural templates inspired by nature. This has resulted in protease inhibitors with exceptional potency and excellent pharmacological and drug-resistance profiles. The design of a stereochemically defined -tetrahydrofuran (-THF) scaffold followed by modifications to promote hydrogen bonding interactions with the backbone atoms of HIV-1 protease led to darunavir, the first clinically approved drug for treatment of drug resistant HIV. Read More

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Recent Developments in Pd(0)-Catalyzed Alkene Carboheterofunctionalization Reactions.

Asian J Org Chem 2017 Jun 10;6(6):636-653. Epub 2017 Mar 10.

Department of Chemistry, University of Michigan, 930 N. University Ave, Ann Arbor, MI, 48109-1055, USA.

This review summarizes recent developments in palladium-catalyzed alkene carboalkoxylation and carboamination reactions. New synthetic methods that have been reported in the past four years are described, along with mechanistic issues and the influence of mechanism on product stereochemistry. The applications of these transformations to the synthesis of natural products and other biologically relevant compounds are also discussed. Read More

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Direct Amination of α-Hydroxy Amides.

Asian J Org Chem 2017 Aug 17;6(8):981-983. Epub 2017 May 17.

A. L. Chandgude, Prof. A. Dömling Department of Drug Design University of Groningen Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands)

A TiCl-mediated reaction for the direct amination of α-hydroxy amides has been developed. This simple, general, additive/base/ligand-free reaction is mediated by economical TiCl. The reaction runs under mild conditions. Read More

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2-Nitrobenzyl Isocyanide as a Universal Convertible Isocyanide.

Asian J Org Chem 2017 Jul 31;6(7):798-801. Epub 2017 Mar 31.

Department of Drug Design, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands).

2-Nitrobenzyl isocyanide is reported as a universal convertible isocyanide with extensive applicability in both Ugi four-component reaction (Ugi-4CR) and Ugi-tetrazole reaction. The cleavage of this isocyanide from 17 examples in both acidic and basic conditions is presented. Additionally, this isocyanide has various handling and synthetic advantages, as it is easy to prepare, odorless, stable, and easy to handle as a solid. Read More

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Chiral Brønsted Acid Catalyzed Kinetic Resolutions.

Asian J Org Chem 2016 Mar 7;5(3):308-320. Epub 2016 Mar 7.

K. Petersen, Department of Chemistry and Biochemistry, University of North Carolina at Greensboro Greensboro, Greensboro, NC 27412.

The synthesis of enantioenriched small molecules is an ongoing goal of organic chemists. This focus review explores the use of kinetic resolutions catalyzed by chiral Brønsted acids. Methods include classic kinetic resolutions and dynamic kinetic resolutions. Read More

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Rapid Construction of (-)-Paroxetine and (-)-Femoxetine via -Heterocyclic Carbene Catalyzed Homoenolate Addition to Nitroalkenes.

Asian J Org Chem 2014 Apr;3(4):442-444

Department of Chemistry, Colorado State University, Fort Collins, CO 80523 (USA).

A concise enantioselective synthesis of (-)-paroxetine () and (-)-femoxetine has been achieved. Key to these syntheses is a -heterocyclic carbene catalyzed homoenolate addition to a nitroalkene followed by in situ reduction of the nitro-group to rapidly access δ-lactams. Read More

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Phosphine-Initiated General-Base-Catalyzed Quinolone Synthesis.

Asian J Org Chem 2014 Apr;3(4):453-457

Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Dr. East, Los Angeles, California 90095-1569 (USA).

Phosphinocatalysis provides a new approach toward 3-substituted-4-quinolones. A simple procedure, which uses PhP as an inexpensive catalyst and -phenyl 2-(-tosylamido)benzothioates and activated alkynes as starting materials, provides direct access to several 3-aroyl-4-quinolones and methyl 4-quinolone-3-carboxylate esters. The reaction presumably occurs through general base catalysis, with the initial addition of PhP to the activated alkyne generating the phosphonium enoate zwitterion, which acts as the strong base that initiates the reaction. Read More

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Concise Synthesis of Linderaspirone A and Bi-linderone.

Asian J Org Chem 2013 Mar 11;2(3):216-219. Epub 2013 Jan 11.

Department of Chemistry & Material Science, Key Laboratory of Synthetic and Natural, Functional Molecule Chemistry of Ministry of Education of China, Northwest University, Xi'an 710069 (China), -88305919.

: The synthesis of linderaspirone A has been accomplished in only three steps by a Darzens cyclopentenedione synthesis and dioxygen-assisted photochemical dimerization. Moreover, the thermal isomerization of linderaspirone A into bi-linderone has been discovered, which may give clues to the biosynthetic pathway for bi-linderone. Read More

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