Hetero-Diels−Alder Reactions of Cyclic Ketone Derived Enamide. A New and Efficient Concept for the Asymmetric Robinson Annulation

Gallier, Florian; Hussain, Hidayat; Martel, Arnaud; Kirschning, Andreas; Dujardin, Gilles

doi:10.1021/ol901065e

Cited by 45 publications

(23 citation statements)

References 27 publications

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“…[185] The acid-catalyzed reaction of the chiral oxazolidinone with a cyclic ketone furnishes the desired dienophile 312 which can react with an alkyl arylidene-pyruvate (311) under Eu(fod) 3 catalysis to yield the desired adduct (313) in high yields (>82 %) with a good endo/exo selectivity (usually >90:10) and with almost complete facial selectivity. After total reduction of the methyl ester group (314), acidic treatment leads to the formation a mixture of REVIEW octalone 316 and 1,5-diketone 315 (which can further be cyclized in the classical conditions).…”

Section: Reviewmentioning

confidence: 99%

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

2017

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The Robinson annulation is a reaction that has been useful for numerous syntheses since its discovery in 1935, especially in the field of steroid synthesis. The products are usually obtained after three consecutive steps: the formation of an enolate (or derivative), a conjugate addition, and an aldol reaction. Over the years, several methodological improvements have been made for each individual step or alternative routes have been devised to access the Robinson annulation products. The first part of this Review outlines the most relevant developments towards the formation of monocarbonyl-derived Robinson annulation products (MRA products, MRAPs) and activated monocarbonyl-derived Robinson annulation products (AMRA products, AMRAPs). The following sections are then devoted to the diastereoselective and enantioselective synthesis of these products, while the last section describes the enantiomeric resolution of racemic mixtures.

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Section: Reviewmentioning

confidence: 99%

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

2017

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“…14 The pyrrole dicarboxaldehyde 9 15, 16 was then coupled under biphasic conditions 17 to afford the key pyrrologlycal 10 .…”

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confidence: 99%

Stereoselective Synthesis of Acortatarins A and B

2012

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Acortatarins A and B have been synthesized via stereoselective spirocyclizations of glycals. Mercury-mediated spirocyclization of a pyrrole monoalcohol sidechain leads to acortatarin A. Glycal epoxidation and reductive spirocyclization of a pyrrole dialdehyde sidechain leads to acortatarin B. Acid equilibration and crystallographic analysis indicate that acortatarin B is a contrathermodynamic spiroketal with distinct ring conformations compared to acortatarin A.

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“…While Cu(SbF 6 ) 2 , Sc(OTf) 3 , and Eu(fod) 3 yielded only the aldol product 20a, the desired HDA product 19a was obtained using La(OTf) 3 , Yb(OTf) 3 , and Y(OTf) 3 . In contrast to the IED-HDA reactions of enamide derived from cyclohexanone, which required refluxing temperature, 8 these reactions were conducted either at room temperature or at 4°C. Solvents were found to play a key role in determining the chemoselectivity.…”

Section: Scheme 5 Direct Asymmetric Aldol Reactions Catalyzed By Enammentioning

confidence: 99%

“…5e Recently, Gallier and coworkers have reported that chiral enamides derived from cyclic ketones can also serve as a dienophile in Eu(fod) 3 catalyzed IED-HDA reactions. 8 The rapid growth of organocatalysis in the last decade has significantly changed the profile of asymmetric catalysis. The first organocatalytic version of the IED-HDA reaction was made possible by the Jorgenson group in 2003.…”

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Asymmetric Inverse-Electron-Demand Hetero-Diels-Alder Reaction via Enamine-Metal Lewis Acid Bifunctional Catalysis

Xu¹,

Wang²

2011

Synlett

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A s y m m e t r i c H e t e r o -D i e l s -A l d e r R e a c t i o nAbstract: This paper describes the development of an efficient and atom-economic asymmetric inverse-electron-demand heteroDiels-Alder reaction of six-membered ketones with b,g-unsaturated a-keto esters via enamine-metal Lewis acid bifunctional catalysis.Asymmetric inverse-electron-demand hetero-DielsAlder (IED-HDA) reactions of an electron-rich alkene with an electron-deficient a,b-unsaturated ketone (enone) offers a convenient and valuable entry to the synthesis of dihydropyran and tetrahydropyran derivatives, which constitute important structural motifs in natural products and a variety of biologically important compounds. 1 In most of the IED-HDA reactions, preformed enol ethers derived from aldehydes act as the electron-rich dienophiles. Very recently, several examples of organocatalytic asymmetric inverse electron HDA reactions have been reported. 2 In these reactions, an enamine, which was formed in situ from a catalytic chiral pyrolidine and an aldehyde, served as the dienophiles. Significant effort has been devoted to the development of asymmetric IED-HDA reactions of aldehyde-derived dienophiles, and impressive results have been obtained. In contrast, the IED-HDA reaction of ketone-derived dienophiles has been much less studied. Herein, we describe some of the common strategies that have been developed for the IED-HDA reactions. In this context, we highlight our recent contribution of the asymmetric IED-HDA reaction of six-membered cyclic ketones with b,g-unsaturated a-keto esters catalyzed by primary amine-based enamine-metal Lewis acid bifunctional catalysts. 3The IED-HDA reaction is controlled by the LUMO of the a,b-unsaturated carbonyl compound and the HOMO of the dienophile. Chiral Lewis acids were initially developed to catalyze the enantioselective addition of electronrich alkenes to a,b-unsaturated carbonyl compounds. This reaction has been extensively investigated over the past decade. Earlier results have been summarized in several recent reviews. 1,4 One of the most important works in this field was the development of Cu-BOX complexes as the Lewis acid catalyst. 5 An early example is the [4+2] cycloaddition of electron-rich enol ether with a b,g-unsaturated a-keto ester reported by the Jorgenson group (Scheme 1, Equation 1). 5a Other chiral Lewis acids have also been developed for the IED-HDA reactions. For example, an IED-HDA reaction of N-sulfonyl-1-aza-1,3-Zhenghu Xu (left) was born in Hubei ) and the Scripps Research Institute (2005)(2006)(2007). She started her independent career as an assistant professor at Miami University in 2007. Her current research focus is on the development of enamine-metal Lewis acid bifunctional catalysts for asymmetric organic transformations, and the design and synthesis of porphyrinbased supermolecules.This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

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Hetero-Diels−Alder Reactions of Cyclic Ketone Derived Enamide. A New and Efficient Concept for the Asymmetric Robinson Annulation

Cited by 45 publications

References 27 publications

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

Stereoselective Synthesis of Acortatarins A and B

Asymmetric Inverse-Electron-Demand Hetero-Diels-Alder Reaction via Enamine-Metal Lewis Acid Bifunctional Catalysis

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