Organic Base‐Catalyzed Stereoselective Isomerizations of 4‐Hydroxy‐4‐phenyl‐but‐2‐ynoic Acid Methyl Ester to (<i>E</i>)‐ and (<i>Z</i>)‐4‐Oxo‐4‐phenyl‐but‐2‐enoic Acid Methyl Esters

Sonye, John P.; Koide, Kazunori

doi:10.1080/00397910500406583

Cited by 19 publications

(4 citation statements)

References 23 publications

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“…We have recently reported the stereoselective isomerization of A (and other electron-deficient propargylic alcohols) to C using catalytic DABCO. , Despite the synthetic and biological importance of esters B , the only general approach toward B is the oxidation of 2-alkoxyfurans that are not readily accessible …”

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confidence: 99%

Sodium Bicarbonate-Catalyzed Stereoselective Isomerizations of Electron-Deficient Propargylic Alcohols to (Z)-Enones

Sonye

Koide

2007

J. Org. Chem.

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Redox isomerization is a synthetically important process because it creates two new functional groups in the product, among which is the isomerization of propargylic alcohols to conjugated enones. Although E-enones have been prepared by this approach, Z-enones could not be accessed. We previously reported DABCO-catalyzed E-selective isomerization of electron-deficient propargylic alcohols to enones and its mechanism. Based on this mechanism, we have now developed the first Z-selective redox isomerization of electron-deficient propargylic alcohol to enone using sodium bicarbonate as a catalyst.

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confidence: 99%

Sodium Bicarbonate-Catalyzed Stereoselective Isomerizations of Electron-Deficient Propargylic Alcohols to (Z)-Enones

Sonye

Koide

2007

J. Org. Chem.

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“…In this review article, we will focus on the asymmetric synthesis of chiral γ-hydroxy-α,β-acetylenic esters and their transformation to other chiral organic molecules. The conversion of γ-hydroxy-α,β-acetylenic esters to achiral products is not discussed in this paper and only selected references are provided [8][9][10][11][12][13][14].…”

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γ-Hydroxy-α,β-acetylenic esters: asymmetric syntheses and applications

Gao

2010

Sci. China Chem.

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γ-Hydroxy-α,β-acetylenic esters are versatile synthetic precursors to many organic compounds. This paper reviews the synthesis of chiral γ-hydroxy-α,β-acetylenic esters by asymmetric reduction of γ-oxo-α,β-acetylenic esters, enantioselective addition to aldehydes in the presence of chiral catalysts, and diastereoselective addition to chiral aldehydes. The preparation of racemic γ-hydroxy-α,β-acetylenic esters is also included. Examples are provided for the application of γ-hydroxy-α,β-acetylenic esters in organic synthesis.γ-hydroxy-α,β-acetylenic ester, asymmetric, enantioselective, diastereoselective

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“…The Trost group later developed an enantioselective method to prepare these compounds 7. γ-Hydroxy-α,β-acetylenic esters are precursors for γ-hydroxy-α,β-alkenyl esters,8 cis- 9,10 and trans-γ-oxo-α,β-alkenyl esters 9,11,12. In our laboratory, γ-hydroxy-α,β-alkenyl ester played a pivotal role in the synthesis of FR901464 13–15.…”

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Cyclic acetal formation between 2-pyridinecarboxyaldehyde and γ-hydroxy-α,β-acetylenic esters

Osman

Koide

2008

Tetrahedron Letters

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A new transformation between 2-pyridinecarboxyaldehyde and γ-hydroxy-α,β-acetylenic esters to form highly functionalized cyclic acetals was discovered. This transformation proceeds under very mild conditions without any additives and is promoted by the basic nature of the pyridine ring.Electron-deficient propargylic alcohols such as γ-hydroxy-α,β-alkenyl esters are important intermediates in organic synthesis due to their potential for further functionalization. [1][2][3][4] As such, development of new synthetic methodologies toward the preparation of these important synthetic intermediates is of interest to many research groups including ours. For example, we showed that highly functionalized γ-hydroxy-α,β-acetylenic esters could be prepared by the coupling of aldehydes, ketones, or epoxides with silver acetylides in the presence of Cp 2 ZrCl 2 and AgOTf. 5,6 The Trost group later developed an enantioselective method to prepare these compounds. 7 γ-Hydroxy-α,β-acetylenic esters are precursors for γ-hydroxy-α,β-alkenyl esters, 8 cis-9,10 and trans-γ-oxo-α,β-alkenyl esters. 9,11,12 In our laboratory, γ-hydroxy-α,β-alkenyl ester played a pivotal role in the synthesis of FR901464. [13][14][15] While studying the scope of zirconium/silver-promoted alkynylation of aldehydes and ketones, we found the interesting reactivity of 2-pyridinecarboxaldehyde toward γ-hydroxy-α,β-acetylenic esters, which is the subject of this communication.In our efforts to develop zirconium/silver-promoted alkynylations of functionalized carbonyl compounds with silver acetylides, 6 the coupling between 2-pyridinecarboxaldehyde (1) and Ag-C≡C-CO 2 Me (2) in the presence of Cp 2 ZrCl 2 gave an intractable mixture (Scheme 1a). We hypothesized that the expected product 3 could react with 1, thereby producing the mixture. To test this hypothesis, a mixture of 4 and 1 (1:1, 0.3 M each) was stirred at 23 °C in CH 2 Cl 2 for 4 d (Scheme 1b). These reaction conditions produced the highly functionalized product 5 in 65% yield, whose structure was confirmed by X-ray crystallography (Figure 1). Interestingly, compound 4 did not react with either 3-or 4-pyridinecarboxyaldehyde. Similar compounds were produced by Evans et al. by using alcohol substrates and potassium t-butoxide with an aldehyde to form 6-membered cyclic acetals. 16 Another work to form very similar 6-membered ring 1,3-dioxan-4-ylidenes was accomplished by Kwon et al. under phosphine catalysis. 17 These examples demonstrate the importance of cyclic acetals in organic synthesis.© 2008 Elsevier Ltd. All rights reserved. *Corresponding author. Tel.: +1-412-624-8767; fax: +1-412-624-8611; e-mail: koide@pitt.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process...

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Organic Base‐Catalyzed Stereoselective Isomerizations of 4‐Hydroxy‐4‐phenyl‐but‐2‐ynoic Acid Methyl Ester to (E)‐ and (Z)‐4‐Oxo‐4‐phenyl‐but‐2‐enoic Acid Methyl Esters

Cited by 19 publications

References 23 publications

Sodium Bicarbonate-Catalyzed Stereoselective Isomerizations of Electron-Deficient Propargylic Alcohols to (Z)-Enones

Sodium Bicarbonate-Catalyzed Stereoselective Isomerizations of Electron-Deficient Propargylic Alcohols to (Z)-Enones

γ-Hydroxy-α,β-acetylenic esters: asymmetric syntheses and applications

Cyclic acetal formation between 2-pyridinecarboxyaldehyde and γ-hydroxy-α,β-acetylenic esters

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