Rhodium-catalyzed chemo- and regioselective decarboxylative addition of β-ketoacids to alkynes

Li, Changkun; Grugel, Christian P.; Breit, Bernhard

doi:10.1039/c6cc02272c

Cited by 69 publications

(29 citation statements)

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“…The Michael addition is one of the most important and fundamental methods for C–C bond construction. The utility of β ‐keto acids as ketone enolate equivalents in Michael addition has been well studied …”

Section: Decarboxylative Enolate Nucleophilesmentioning

confidence: 99%

“…Rhodium (1 mol‐%)‐catalyzed decarboxylative cross‐couplings of β ‐keto acids and allenes 10.1 [5a] or in situ generated allenes 10.3 [5b], [5c] from alkynes have been studied by the Breit[5a], [5c] and Dong group. [5b] Decarboxylative additions to terminal allenes successfully yielded tertiary or quaternary carbon centers (Equation 10–1). Rh‐insertion 10.2 and β‐ hydride elimination make methyl alkynes convert into allenes 10.3 [5b], [5c] (Scheme ).…”

Section: Decarboxylative Enolate Nucleophilesmentioning

confidence: 99%

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β‐Keto Acids in Organic Synthesis

et al. 2020

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Recent advances of -keto acids were summarized as five categories according to their triggered mechanisms:(1) decarboxylative enolate nucleophiles;(2) addition without [a] 526 Scheme 3. Reactions with in situ generated isatylidenemalononitriles.Scheme 4. 1,3-Acetonedicarboxylic acid as 1,3-bis-pro-nucleophile. could promote decarboxylative Michael reactions of unreactive substrates. Besides, an asymmetric chiral bis(oxazoline) copper(II)-catalyst 5.5 would achieve the single-pot procedure to prepare 5.4 (Scheme 5).Scheme 5. Michael/aldol reaction. The Chiba group [3i] presented a manganese(III)-catalyzed preparation of pyrroles 6.2 from reactions of vinyl azides 6.1 with -keto acids (Equation 6-1). It might be initiated by a radical pathway, giving iminyl radical 6.3 by releasing of N 2 , and CO 2 . Then, 6.3 underwent intramolecular addition to give inter-Eur. J. Org. Chem. 2020, 525-538 www.eurjoc.org 528 Scheme 10. Addition to allenes.Scheme 11. Coupling with alkenes.Scheme 12. Aldol reactions from α,α-difluoro--keto acid derivatives.

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Section: Decarboxylative Enolate Nucleophilesmentioning

confidence: 99%

Section: Decarboxylative Enolate Nucleophilesmentioning

confidence: 99%

β‐Keto Acids in Organic Synthesis

et al. 2020

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“…Anschließend wurde eine verwandte Methode ausgehend von internen Alkinen als Kupplungspartnern entwickelt und in den Synthesen verschiedener Heterocyclen angewendet (Schema ) . Ebenfalls 2016 gelang den Arbeitsgruppen um Breit und Dong mit einer decarboxylierenden Addition von β‐Ketosäuren an interne Alkine zeitgleich ein direkter Zugang zu γ,δ‐ungesättigten Ketonen (Schema ) ,…”

Section: Alkine Als Elektrophile π‐Allyl‐vorstufenunclassified

Alkine als alternativer Einstieg in elektrophile und nukleophile Übergangsmetall‐katalysierte Allylierungen

et al. 2017

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Eine Reihe von Übergangsmetall‐Katalysatoren ist in der Lage, terminale und interne Alkine intermediär in entsprechende Allylmetall‐Verbindungen zu überführen, die ihrerseits elektrophile oder nukleophile Reaktivitäten aufweisen können. Während klassische Methoden zur Herstellung von Allylmetall‐Spezies oftmals von der Bildung stöchiometrischer Mengen an Nebenprodukten begleitet sind, ermöglicht der Einsatz von Alkinen als Allylmetall‐Vorstufen vollständig atomökonomische katalytische Prozesse, die außerdem mit hohen Enantioselektivitäten ablaufen.

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“…[9,17,18] Applying the commercially available (R)-DTBM-Garphos as ap rivileged ligand, ac lean allylic etherification of phenylmethyl alkyne could be observed, thus furnishing the allylic ether 5a in 63 %y ield and with 89 % ee (Table 3). [9,17,18] Applying the commercially available (R)-DTBM-Garphos as ap rivileged ligand, ac lean allylic etherification of phenylmethyl alkyne could be observed, thus furnishing the allylic ether 5a in 63 %y ield and with 89 % ee (Table 3).…”

Section: Zuschriftenmentioning

confidence: 99%

“…To our delight, only aslight change of our initial reaction conditions in terms of the ligand and reaction temperature paved the way to alkynes as suitable reaction partners. [9,17,18] Applying the commercially available (R)-DTBM-Garphos as ap rivileged ligand, ac lean allylic etherification of phenylmethyl alkyne could be observed, thus furnishing the allylic ether 5a in 63 %y ield and with 89 % ee (Table 3). At this point, the absolute configuration of 5a could be assigned upon comparison of the optical rotation with known data.…”

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confidence: 99%

Rhodium‐Catalyzed Enantioselective Intermolecular Hydroalkoxylation of Allenes and Alkynes with Alcohols: Synthesis of Branched Allylic Ethers

Breit

2016

Angewandte Chemie

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Regio-and enantioselective additions of alcohols to either terminal allenes or internal alkynes provides access to allylic ethers by using a Rh I /diphenyl phosphate catalytic system. This method provides an atom-economic way to obtain chiral aliphatic and aryl allylic ethers in moderate to good yield with good to excellent enantioselectivities.Allylic ethers are key components of bioactive molecules and natural products and serve as versatile synthetic intermediates for further construction of numerous structures [1] through a wide variety of reactions such as [2,3] and [3,3] sigmatropic rearrangements and olefin metathesis reactions, among many others.[1b, 2, 3] Significant progress towards their synthesis has been achieved recently by employing transition metal catalyzed allylic substitution. In most cases, allyl acetates [4] or carbonates [5] have been used as electrophiles. However, recent studies show that even allylic alcohols can serve as allyl precursors.[6] To date, premetalated alkoxides have been used as nucleophiles along with metals to soften the hard nucleophilic character of an alkoxide (such as tin, [4a] boron, [7] zinc, [4b,c, 5f] and copper [5a,c-e] ). Following on the initial work with palladium catalysts of the groups of Trost [8] and Yamamoto, [9] we recently reported on a series of rhodium-catalyzed pronucleophile addition reactions to allenes and alkynes, reactions that can be regarded as atom-economic alternatives to allylic substitution chemistry displaying complementary branch regioselectivity (Scheme 1). [10] Thus, hydroamination, [11] hydroesterification, [12] hydroacylation, [13] and hydrothiolation [14] have been achieved to afford versatile enantioenriched branched allylic products. In this context, it would be highly interesting if simple and non-deprotonated alcohols could be added atom economically to allenes or even to alkynes, thus giving valuable branched allylic ether products.We herein report on the implementation of such a transformation allowing the highly regio-and enantioselective addition of simple and functionalized alcohols, including methanol and ethanol, to terminal allenes and internal alkynes to give a wide range of valuable building blocks for synthetic organic chemistry.Initial reactions were conducted with 3-phenylpropyl allene (1 a) and ethanol (2 b) as model substrates. First reactivity assays indicated that the presence of an acidic cocatalyst was necessary. The reaction proved to work using a rhodium(I)/DPEphos/diphenyl phosphate catalyst in dichloromethane (DCM) at 40 8C for 18 hours and furnished the desired allylic ether in 34 % yield (Table 1, entry 1). [15] Inspired by this result, various chiral bidentate diphosphine ligands with different backbones were subjected to this model reaction. While many standard privileged chiral ligands failed to catalyze this reaction, [16] the chiral ferrocene-type ligand L4 proved to be the best (entries 5 and 6). To our delight, switching the solvent from DCM to 1,2-dichloroethane (DCE) gave th...

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Rhodium-catalyzed chemo- and regioselective decarboxylative addition of β-ketoacids to alkynes

Cited by 69 publications

References 69 publications

β‐Keto Acids in Organic Synthesis

β‐Keto Acids in Organic Synthesis

Alkine als alternativer Einstieg in elektrophile und nukleophile Übergangsmetall‐katalysierte Allylierungen

Rhodium‐Catalyzed Enantioselective Intermolecular Hydroalkoxylation of Allenes and Alkynes with Alcohols: Synthesis of Branched Allylic Ethers

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