Synthesis and Application of β‐Substituted Pauson–Khand Adducts: Trifluoromethyl as a Removable Steering Group

Aiguabella, Nuria; Pozo, Carlos del; Fustero, Santos; Riéra, Antoni

doi:10.1002/anie.201300907

Cited by 27 publications

(15 citation statements)

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“…In a later study [ 72 ], Riera and Fustero generalized the use of trifluoromethylalkynes as substrates for the PKR. The copper-catalyzed trifluoromethylation of terminal alkynes described by Qing and co-workers [ 73 ] allowed the efficient preparation of a small library of substrates bearing aryl, alkyl, and alkenyl substitutents.…”

Section: Reviewmentioning

confidence: 99%

Pauson–Khand reaction of fluorinated compounds

Escorihuela¹,

Sedgwick²,

Llobat³

et al. 2020

Beilstein J. Org. Chem.

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The Pauson–Khand reaction (PKR) is one of the key methods for the construction of cyclopentenone derivatives, which can in turn undergo diverse chemical transformations to yield more complex biologically active molecules. Despite the increasing availability of fluorinated building blocks and methodologies to incorporate fluorine in compounds with biological interest, there have been few significant advances focused on the fluoro-Pauson–Khand reaction, both in the inter- and intramolecular versions. Furthermore, the use of vinyl fluorides as olefinic counterparts had been completely overlooked. In this review, we collect the advances both on the stoichiometric and catalytic intermolecular and intramolecular fluoro-Pauson–Khand reaction, with special attention to the PKR of enynes containing a fluoride moiety.

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Section: Reviewmentioning

confidence: 99%

Pauson–Khand reaction of fluorinated compounds

Escorihuela¹,

Sedgwick²,

Llobat³

et al. 2020

Beilstein J. Org. Chem.

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“…Regioselectivity in other intermolecular [2+2+1] reactions such as the Pauson-Khand reaction is often difficult to achieve in the absence of clear stereoelectronic differentiation of alkyne substituents, and remains a siginficant synthetic challenge. [10] In an effort to design more useful and practical pyrrole syntheses, we have explored several routes to the chemo- and regioselective heterocoupling of alkynes in the [2+2+1] reaction to yield highly substituted pyrroles. Herein, we report that silyl-protected alkynes serve as excellent heterocoupling partners, yielding pentasubstituted N-aryl pyrroles in high chemo- and regioselectivity (Figure 1, bottom).…”

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confidence: 99%

Trimethylsilyl‐Protected Alkynes as Selective Cross‐Coupling Partners in Titanium‐Catalyzed [2+2+1] Pyrrole Synthesis

Chiu

Tonks

2018

Angew Chem Int Ed

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Trimethylsilyl (TMS)-protected alkynes serve as selective alkyne cross coupling partners in Ti-catalyzed [2+2+1] pyrrole synthesis. Reactions of TMS-protected alkynes with internal alkynes and azobenzene catalyzed by Ti imido catalysts yield pentasubstituted 2-TMS-pyrroles with greater than 90% selectivity over the other 9 possible pyrrole products. The steric and electronic effects of the TMS group have both been identified to play key roles in this highly selective pyrrole synthesis. This strategy provides a convenient methodology to synthesize multisubstituted pyrroles as well as an entrypoint into further pyrrole diversification through facile modification of the resulting 2-silylpyrrole products, as demonstrated through a short formal synthesis of the marine natural product Lamellarin R.

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“…28 More recently, the Riera group demonstrated the utility of trifluoromethyl as a removable steering group that can be released from -substituted Pauson-Khand products by treatment with DBU in nitromethane/H 2 O. 29 Furthermore, Reira reported that ethylene glycol as an additive can significantly accelerate intermolecular Pauson-Khand reactions, doubling the yields, even for challenging combinations such as cyclopentene/(trimethylsilyl)acetylene or cyclopentene/N-Boc-propargylamine. 30 In an earlier work, we found that chlorinated solvents such as CH 2 Cl 2 could be replaced by either an ionic liquid such as 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF 6 ) or a two-phase system such as [bmim]PF 6 /methylcyclohexane (MCH) in intermolecular Co 2 (CO) 8 -mediated Pauson-Khand reactions in the presence of NMO at room temperature with good yields and regioselectivities for bicyclic alkenes, such as norbornene (26) (Scheme 3).…”

Section: Syn Lettmentioning

confidence: 99%

Adventures and Detours in the Synthesis of Hydropentalenes

Deimling

Zens

Park

et al. 2020

Synlett

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Functionalized hydropentalenes (i.e., bicyclo[3.3.0]octanones) constitute important building blocks for natural products and for ligands for asymmetric catalysis. The assembly and tailored functionalization of this convex roof-shaped scaffold is challenging and has motivated a variety of synthetic approaches including our own contributions, which will be presented in this account.1 Introduction2 Biosynthesis of Hydropentalenes3 Hydropentalenes through the Pauson–Khand Reaction4 Hydropentalenes through Transannular Oxidative Cyclization of Cycloocta-1,4-diene5 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Dodecahydrocyclopenta[a]indenes6 Functionalization of Bicyclo[3.3.0]octan-1,4-diones to Crown Ether Hybrids7 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Cylindramide8 Tandem Ring-Opening Metathesis/Ring-Closing Metathesis/Cross-Metathesis of Bicyclo[2.2.1]heptanes9 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Geodin A10 Hydropentalenes through Enantioselective Desymmetrization of Weiss Diketones11 Functionalization of Weiss Diketones by Carbonyl Ene Reactions12 Functionalization of the Weiss Diketone to Cylindramide and Geodin A Core Units13 Biological Properties of Bicyclo[3.3.0]octanes14 Hydropentalenes through Vinylcyclopropane Cyclopentene Rearrangement15 Functionalization of Bicyclo[3.3.0]octanes toward Chiral Dienes16 Miscellaneous Syntheses of Hydropentalenes17 Conclusion and Outlook

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Synthesis and Application of β‐Substituted Pauson–Khand Adducts: Trifluoromethyl as a Removable Steering Group

Abstract: Against the rules: The synthesis of the previously unknown β‐substituted regioisomers of the intermolecular Pauson–Khand reaction of terminal alkynes is reported. This regiochemistry was achieved by using the trifluoromethyl group as a removable directing group on the alkyne.

Cited by 27 publications

References 47 publications

Pauson–Khand reaction of fluorinated compounds

Pauson–Khand reaction of fluorinated compounds

Trimethylsilyl‐Protected Alkynes as Selective Cross‐Coupling Partners in Titanium‐Catalyzed [2+2+1] Pyrrole Synthesis

Adventures and Detours in the Synthesis of Hydropentalenes

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