Cinchona Alkaloid Catalyzed Enantioselective [4 + 2] Annulation of Allenic Esters and in Situ Generated ortho-Quinone Methides: Asymmetric Synthesis of Functionalized Chromans

Enantioselective organocatalytic domino reactions of in situ generated ortho-quinone methides with malononitrile and β-functionalized ketones have been developed. This strategy could generate various chiral chromenes in high yields and stereoselectivities.

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Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

Current Organic Chemistry ◽

10.2174/1385272824999200407093625 ◽

2020 ◽

Vol 24 (8) ◽

pp. 900-908

Author(s):

Ram Naresh Yadav ◽

Amrendra K Singh ◽

Bimal Banik

Keyword(s):

Asymmetric Synthesis ◽

Chiral Auxiliary ◽

Bioactive Molecules ◽

One Pot ◽

Enantiomerically Pure ◽

Stereoselective Glycosylation ◽

One Pot Synthesis ◽

Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

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Strategies of In Situ Generated Magnesium Catalysis in Asymmetric Reactions

Synlett ◽

10.1055/a-1409-2734 ◽

2021 ◽

Author(s):

Dongxu Yang ◽

Linqing Wang

Keyword(s):

Asymmetric Synthesis ◽

Alkaline Earth ◽

Earth Metal ◽

Asymmetric Reactions ◽

Chiral Ligands ◽

Alkaline Earth Metal ◽

Enantioselective Reactions ◽

Earth's Crust

AbstractMagnesium (Mg) is a cheap, non-toxic, and recyclable alkaline earth metal that constitutes about 2% weight in the Earth’s crust. The use of magnesium catalysts to forge chiral moieties in molecules is highly attractive. Based on our work in recent years, we describe the current progress in the development of in situ generated magnesium catalysts and their application in asymmetric synthesis. In this perspective, a critically concise classification of in situ generated magnesium catalytic modes, with relevant examples, is presented, and representative mechanisms of each category are discussed. Building on the established diverse strategies, one can foresee that more innovative and structurally creative magnesium catalysts that are generated in situ will be developed to overcome more formidable challenges of catalytic enantioselective reactions.1 Introduction2 Magnesium Catalysts Generated in Situ from Chiral Ligands Containing Dual Reactive Hydrogens3 Magnesium Catalysts Generated in Situ from Monoanionic Chiral Ligands4 Bimetallic and Polymetallic Magnesium Catalysts Assembled in Situ5 Summary and Outlook

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Lewis acid-catalyzed tandem cyclization of in situ generated o-quinone methides and arylsulfonyl hydrazides for a one-pot entry to 3-sulfonylbenzofurans

Organic Chemistry Frontiers ◽

10.1039/c9qo01196j ◽

2019 ◽

Vol 6 (24) ◽

pp. 3929-3933 ◽

Cited By ~ 2

Author(s):

Fan-Xiao Meng ◽

Ruo-Nan Wang ◽

Hong-Li Huang ◽

Shu-Wen Gong ◽

Qian-Li Li ◽

...

Keyword(s):

Lewis Acid ◽

Quinone Methides ◽

One Pot ◽

Acid Catalyzed ◽

Tandem Cyclization ◽

First Time

Lewis acid-mediated one-pot tandem cyclization of o-QMs with arylsulfonyl hydrazides was described for the first time and the corresponding 3-sulfonylbenzofuran products were obtained in moderate to good yields.

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