A Sphingolipid Fatty Acid Constituent Made by Alkyne <i>trans</i>‐Hydrogenation: Total Synthesis of Symbioramide

Radkowski, Karin; Fürstner, Alois

doi:10.1002/adsc.202200540

Cited by 4 publications

(3 citation statements)

References 81 publications

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“…shift 1 to the corresponding (E)-alkene as the final product; gem-hydrogenation 2 is hence innately linked to alkyne trans-hydrogenation, [1,7] which itself is a rather unorthodox but synthetically enabling transformation. [5,6,8,9] Importantly, however, it is also possible to outperform this downstream pathway and, in doing so, harness genuine carbene reactivity: a set of previously unknown transformations, including hydrogenative cyclopropanation, [10] hydrogenative metathesis, [10,11] hydrogenative rearrangement and cycloisomerization reactions, [12,13] hydrogenative heterocycle syntheses, [14] and hydrogenative CÀ H insertions [15] bear witness of this notion.…”

Section: Introductionmentioning

confidence: 99%

“… [2,3] This outcome was ascertained by spectroscopic and crystallographic means, and the course of the reaction is now well understood on the basis of extensive computational studies at the DFT and the Coupled Cluster level of theory [2–4] . Under the hydrogen atmosphere, the reactive metal carbene intermediate thus formed evolves by formal 1,2‐H shift 1 to the corresponding ( E )‐alkene as the final product; gem ‐hydrogenation 2 is hence innately linked to alkyne trans ‐hydrogenation, [1,7] which itself is a rather unorthodox but synthetically enabling transformation [5,6,8,9] . Importantly, however, it is also possible to outperform this downstream pathway and, in doing so, harness genuine carbene reactivity: a set of previously unknown transformations, including hydrogenative cyclopropanation, [10] hydrogenative metathesis, [10,11] hydrogenative rearrangement and cycloisomerization reactions, [12,13] hydrogenative heterocycle syntheses, [14] and hydrogenative C−H insertions [15] bear witness of this notion.…”

Section: Introductionmentioning

confidence: 99%

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Light‐Driven Alkyne gem‐Hydrogenation: An Intramolecular Approach to Hoveyda–Grubbs Catalysts

Saiegh

Biberger

Zachmann

et al. 2022

Helvetica Chimica Acta

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The light‐driven gem‐hydrogenation of internal alkynes in the presence of [(NHC)(η6‐cymene)RuCl2] generates discrete ruthenium carbene complexes. When applied to appropriately designed enyne substrates, the reactive intermediates thus formed will engage the tethered olefin in metathetic ring closure while splitting off a Hoveyda–Grubbs‐type complex as secondary carbene. This unconventional approach to these classical catalysts for olefin metathesis rivals existing methodology in that it is safe, short, phosphine‐free, and uses readily available starting materials.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Light‐Driven Alkyne gem‐Hydrogenation: An Intramolecular Approach to Hoveyda–Grubbs Catalysts

Saiegh

Biberger

Zachmann

et al. 2022

Helvetica Chimica Acta

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“…The development of catalytic methods that enable their transformation into other value-added functionalities or structures is a highly interesting yet challenging topic from both academic and industrial perspectives . In this regard, the selective difunctionalization of alkynes has been explored as an important strategic entry to access stereodefined alkenes and is frequently utilized in assembling complex pharmaceutical molecules . Regio- and stereoselective control comprise the central challenges in the quest of transforming linear entities into tetrahedral ones (Figure A) .…”

mentioning

confidence: 99%

Asymmetric anti-Selective Borylalkylation of Terminal Alkynes by Nickel Catalysis

Huang,

Wu,

et al. 2023

J. Am. Chem. Soc.

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Selective transformation of alkyne triple bonds to double bonds serves as an efficient platform to construct substituted alkenes. While significant advances have been made in its spatiotemporal regulation, achieving a multicomponent enantioselective reaction that requires multifaceted selectivity issues to be overcome is still uncommon. Here, we report an unprecedented asymmetric anti-stereoselective borylcarbofunctionalization of terminal alkynes by nickel catalysis. The utilization of an inexpensive chiral diamine ligand enables the three-component cross-coupling of terminal alkynes, a diboron reagent, and prochiral alkyl electrophiles with high levels of regio-, stereo-, and enantioselectivities. This reaction provides an efficient protocol to access enantioenriched alkenyl esters bearing an α-stereogenic center, is remarkably practical, and has a broad scope and an outstanding functional group compatibility. In addition, the value of this method has been highlighted in a diversity of follow-up stereoretentive derivatizations and the stereoselective concise synthesis of complex drug molecules.

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How to Break the Law: trans‐Hydroboration and gem‐Hydroboration of Alkynes

Fürstner

2023

Israel Journal of Chemistry

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Classical hydroboration is the textbook example of an organometallic reaction under rigorous frontier orbital control: a synergetic bonding mode between substrate and reagent evolves into a four‐membered transition state that enforces syn/suprafacial delivery of H−BR2 to the π‐system. This strict stereochemical “law” remained valid for decades, even after the advent of metal‐catalyzed hydroboration. During the last decade, however, numerous possibilities emerged that allow this paradigm to be challenged. Thus, direct trans‐hydroboration of terminal as well as internal alkynes was achieved through radical, ionic, organocatalytic, and metal‐catalyzed manifolds, which are summarized in this review. Among them, pathways involving either metal vinylidenes (Rh, Ir, Ru, Fe) derived from terminal alkynes or metallacyclopropenes (η2‐vinylmetal complexes) derived from an internal triple bond and a [CpXRu]‐based catalyst represent the currently most widely applicable solutions. The latter type of intermediates is also accountable for the equally perplexing gem‐hydroboration of alkynes: geminal delivery of a borane to a triple bond has no precedent in the classical canon. The only forerunner was gem‐hydrogenation, which represents an unconventional yet highly useful entry into discrete ruthenium carbene complexes. The close mechanistic ties between these transformations are outlined, and brief reference is also made to remotely related reactions such as trans‐diboration and trans‐carboboration.

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A Sphingolipid Fatty Acid Constituent Made by Alkyne trans‐Hydrogenation: Total Synthesis of Symbioramide

Cited by 4 publications

References 81 publications

Light‐Driven Alkyne gem‐Hydrogenation: An Intramolecular Approach to Hoveyda–Grubbs Catalysts

Light‐Driven Alkyne gem‐Hydrogenation: An Intramolecular Approach to Hoveyda–Grubbs Catalysts

Asymmetric anti-Selective Borylalkylation of Terminal Alkynes by Nickel Catalysis

How to Break the Law: trans‐Hydroboration and gem‐Hydroboration of Alkynes

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