نتایج جستجو برای: diastereoselective synthesis

تعداد نتایج: 409824  

Journal: :Organic & biomolecular chemistry 2010
Romain Blanc Virginie Héran Raphaël Rahmani Laurent Commeiras Jean-Luc Parrain

An efficient synthesis of deoxy-lambertellols was reported through a highly chemo- and diastereoselective intermolecular Diels-Alder cycloaddition between trans-1,2-disiloxybenzocyclobutenes and 2-methylprotoanemonine. Such transformation with δ-substituted γ-alkylidenebutenolides, to prepare new analogues of these tricyclic spirolactones, which would be very difficult to prepare by other ways,...

Journal: :The Journal of organic chemistry 2011
David Crich

This Perspective outlines work in the Crich group on the diastereoselective synthesis of the so-called difficult classes of glycosidic bond: the 2-deoxy-β-glycopyranosides, the β-mannopyranosides, the α-sialosides, the α-glucopyranosides, and the β-arabinofuranosides with an emphasis on the critical interplay between mechanism and methodology development.

Journal: :Chemical communications 2014
Sandra Börding Thorsten Bach

The C24-C40 fragment of (-)-pulvomycin was prepared in enantiomerically pure form using a concise synthesis method (15 linear steps from D-fucose, 6.8% overall yield) featuring a diastereoselective addition to an aldehyde, a β-selective glycosylation and a Stille cross-coupling as the key steps.

Journal: :Chemical communications 2012
Enrique Alvarez-Manzaneda Rachid Chahboun Esteban Alvarez Antonio Fernández Ramón Alvarez-Manzaneda Ali Haidour Jose Miguel Ramos Ali Akhaouzan

The first enantiospecific synthesis of akaol A, a marine sesquiterpene quinol, has been achieved. Key steps of the synthetic sequence are the oxidative degradation of (-)-sclareol to a dinorlabdane ketoester, mediated by the ozone-lead(IV) acetate system, the diastereoselective α-methylation of a ketoaldehyde, followed by an intramolecular aldol condensation and the further Diels-Alder cycloadd...

Journal: :Organic letters 2012
Bhaskar Reddy Kusuma Gary E L Brandt Brian S J Blagg

Cruentaren A, an antifungal benzolactone produced by the myxobacterium Byssovorax cruenta, is highly cytotoxic against various human cancer cell lines and a highly selective inhibitor of mitochondrial F-ATPase. A convergent and efficient synthesis of cruentaren A is reported, based upon a diastereoselective alkylation, a series of stereoselective aldol reactions utilizing Myers' pseudoephedrine...

Journal: :Acta poloniae pharmaceutica 2006
Jacek Gawroński

A review of currently used methods for the synthesis and resolution of enantiomers of drugs and their precursors is presented. For the synthesis part the methods of diastereoselective as well as enantioselective synthesis are discussed, with particular consideration given to enantioselective catalysis with either metal complexes or biocatalysts. Desymmetrization processes are also included as m...

Journal: :Organic & biomolecular chemistry 2008
Nicholas P Mulholland Gerald Pattenden Iain A S Walters

A 14-step total synthesis of (+/-)-salinosporamide A (1), a potent inhibitor of the 20S proteasome isolated from the marine bacterium Salinospora tropica, is described. The synthesis is based on a diastereoselective intramolecular aldolisation of a substituted beta-keto amide intermediate, i.e. 13, derived from a beta-keto acid, viz. 21, and an alpha-amino malonate, leading to the pyrrolidinone...

Journal: :Organic & biomolecular chemistry 2012
Gangavaram V M Sharma Sheri Venkat Reddy Kallaganti V S Ramakrishna

The synthesis of the macrolactone core of (+)-neopeltolide has been achieved. The key synthetic strategy involves the highly diastereoselective synthesis of the 2,6-cis-disubstituted tetrahydropyran ring by a transannular cyclization of δ-hydroxy alkene using mercuric trifluoroacetate. Two of the six stereocenters C-5 and C-11 were realized from L-malic acid, while the remaining stereocenters C...

2016
R. N. Straker Q. Peng A. Mekareeya R. S. Paton E. A. Anderson

Transition metals can catalyse the stereoselective synthesis of cyclic organic molecules in a highly atom-efficient process called cycloisomerization. Many diastereoselective (substrate stereocontrol), and enantioselective (catalyst stereocontrol) cycloisomerizations have been developed. However, asymmetric cycloisomerizations where a chiral catalyst specifies the stereochemical outcome of the ...

Journal: :Beilstein Journal of Organic Chemistry 2006
Pradeep K Mohakhud Sujeet MR Kumar Vasanth MR Kumar Ravi MR Kumar Moses DR Babu Vyas DR K Om DR Reddy

BACKGROUND The formation of novel N-substituted-1,2,3,4-tetrahydro[1,3]-dioxolo-[6,7]-5H-[1]benzopyrano [3,4-c]pyridines were observed unexpectedly during the acid-mediated ketal removal of ethylenedioxy ketal protected 4-piperidones. The literature revealed that benzopyranopyridine derivatives are of scientific interest and some exhibit interesting biological activities. Diastereomeric resolut...

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