Asymmetric alkynylation of aldehydes with propiolates without high reagent loading and any additives

Kojima, Naoto; Nishijima, Shogo; Tsuge, Kaoru; Tanaka, Tetsuaki

doi:10.1039/c1ob05489a

Cited by 19 publications

(6 citation statements)

References 32 publications

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“…Of the various procedures investigated, the method developed by Kojima and co-workers was the most practical in that only 1.5 equivalents of 16 were needed to reach full conversion of 13. [25] For high diastereoselectivity however,t he steering aminoalcohol 24 described in the literature had to be supplanted by the more bulky analogue 25,w hich furnished the desired adduct 17 with ad.r. of > 95:5.…”

Section: Michael Fuchs and Alois Fürstner*mentioning

confidence: 99%

trans‐Hydrogenation: Application to a Concise and Scalable Synthesis of Brefeldin A

Fuchs

Fürstner

2015

Angew Chem Int Ed

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The important biochemical probe molecule brefeldin A (1) has served as an inspirational target in the past, but none of the many routes has actually delivered more than just a few milligrams of product, where documented. The approach described herein is clearly more efficient; it hinges upon the first implementation of ruthenium-catalyzed trans-hydrogenation in natural products total synthesis. Because this unorthodox reaction is selective for the triple bond and does not touch the transannular alkene or the lactone site of the cycloalkyne, it outperforms the classical Birch-type reduction that could not be applied at such a late stage. Other key steps en route to 1 comprise an iron-catalyzed reductive formation of a non-terminal alkyne, an asymmetric propiolate carbonyl addition mediated by a bulky amino alcohol, and a macrocyclization by ring-closing alkyne metathesis catalyzed by a molybdenum alkylidyne.

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Section: Michael Fuchs and Alois Fürstner*mentioning

confidence: 99%

trans‐Hydrogenation: Application to a Concise and Scalable Synthesis of Brefeldin A

Fuchs

Fürstner

2015

Angew Chem Int Ed

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“…[18] Efficient asymmetric alkyne addition often requires the use of relatively high catalyst loadings and an excess of alkyne and dialkylzinc reagents. [19] Our aim was to develop an efficient chiral catalyst system capable of adding functionalized alkynes to a wide range of aldehydes while minimizing the use of excess reagents and stoichiometric additives, improving the atom economy of this transformation. [20] This would ultimately enable facile access to chiral propargyl alcohols and entry into alkyne-based strategies in the synthesis of natural products.…”

Section: Introductionmentioning

confidence: 99%

Development of Zn–ProPhenol‐Catalyzed Asymmetric Alkyne Addition: Synthesis of Chiral Propargylic Alcohols

Trost

Bartlett

Weiss

et al. 2012

Chemistry A European J

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The development of a general and practical zinc-catalyzed enantioselective alkyne addition methodology is reported. Commercially available ProPhenol ligand (1) has facilitated the addition of a wide range of zinc alkynylides to aryl, aliphatic and α,β-unsaturated aldehydes in high yield and enantioselectivity. New insights into the mechanism of this reaction have resulted in a significant reduction in reagent stoichiometry, enabling the use of precious alkynes and avoiding the use of excess dimethylzinc. The enantioenriched propargylic alcohols from this reaction serve as versatile synthetic intermediates and have enabled efficient syntheses of several complex natural products.

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“…Aldehyde 194 was coupled with the terminal alkyne 197 120 by modification of a method originally developed by Kojima and co-workers (Scheme 16); 121 only the bulky aminoalcohol 198 as chiral ligand would allow the addition reaction to proceed with high diastereoselectivity. trans-Reduction of the resulting ynoate 199 was accomplished with Red-Al at low temperature.…”

Section: Trans-hydrogenation In Natural Product Synthesismentioning

confidence: 99%

Progress in the trans-Reduction and trans-Hydrometalation of Internal Alkynes. Applications to Natural Product Synthesis

Frihed

Fürstner

2016

Bulletin of the Chemical Society of Japan

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The classical repertoire of synthetic organic chemistry is short of methods that allow triple bonds to be transformed into (E)-alkenes with high selectivity in the presence of other reducible sites. Recent advances, most notably in ruthenium-catalyzed trans-hydrogenation, trans-hydrosilylation, trans-hydrogermylation, trans-hydrostannation, and even trans-hydroboration hold the promise of filling this gap. This review illustrates the state-of-the-art in the field by summarizing applications of these emerging methodologies to natural product synthesis. A comparison of ruthenium-catalyzed and radical-induced trans-hydrostannations provides further insights into the application profile of these transformations

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Asymmetric alkynylation of aldehydes with propiolates without high reagent loading and any additives

Cited by 19 publications

References 32 publications

trans‐Hydrogenation: Application to a Concise and Scalable Synthesis of Brefeldin A

trans‐Hydrogenation: Application to a Concise and Scalable Synthesis of Brefeldin A

Development of Zn–ProPhenol‐Catalyzed Asymmetric Alkyne Addition: Synthesis of Chiral Propargylic Alcohols

Progress in the trans-Reduction and trans-Hydrometalation of Internal Alkynes. Applications to Natural Product Synthesis

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