Transition Metal Catalyzed Decarboxylative Additions of Enolates

Tunge, Jon A.; Burger, Erin C.

doi:10.1002/ejoc.200400865

Cited by 161 publications

(34 citation statements)

References 49 publications

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“…[4] We also briefly investigated decarboxylative etherification. [37][38][39][40][41][42][43] This reaction [Eq. (4)] formed the allylic ether in 84 % ee.…”

Section: Methodsmentioning

confidence: 99%

Direct, Iridium‐Catalyzed Enantioselective and Regioselective Allylic Etherification with Aliphatic Alcohols

2008

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Keywordsalkoxides; allylic substitution; asymmetric synthesis; iridium; metallacycle Intermolecular, enantioselective allylic substitution with alcohols [1,2] remains an undeveloped catalytic process. Few reports have been published that describe the intermolecular allylation of aliphatic alcohols with high yield and enantioselectivity, [3] and the most selective of these systems has required copper additives.[4] The large number of α chiral ethers and oxygen heterocycles in natural products and pharmaceutical candidates makes enantioselective routes to these materials important.This transformation has been difficult because alcohols are poor nucleophiles for allylic substitution, and the high basicity of alkoxides can induce elimination processes and catalyst deactivation. Thus, phenoxides, [5][6][7][8][9][10][11][12] Herein we report that primary, secondary, and tertiary alcohols, as well as silanols, can participate directly in catalytic asymmetric allylic substitution in the presence of an alkali metal base. Reactions conducted with a metallacyclic iridium catalyst [24][25][26][27][28][29][30][31][32][33] form chiral, branched allylic ethers and silyl ethers in high yield and high enantioselectivity.[3] These results reveal convenient procedures for the use of alcohol nucleophiles, improve the scope and yield of the allylation of primary, secondary, and tertiary alcohols, and include the use of a catalytic amount of an alkyne additive to suppress olefin isomerization that forms vinyl ether side products. More generally, these results show that alkali metal alkoxides in low concentrations can be competent nucleophiles for allylic substitution.Our efforts to develop a direct allylation of alcohols began with studies of the reaction of cinnamyl acetate (1) with benzyl alcohol (2) in the presence of [{Ir(cod)Cl} 2 ] (cod=1,5-cyclooctadiene) and phosporamidite L1 as precursors to the metallacyclic iridium catalyst [Ir ** We are grateful to the NIH (NIGMS GM-55382) for support of this work and Johnson-Matthey for iridium. S.U. acknowledges the J.S.P.S. fellowships for young scientists.

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“…[4] We also briefly investigated decarboxylative etherification. [37][38][39][40][41][42][43] This reaction [Eq. (4)] formed the allylic ether in 84 % ee.…”

Section: Methodsmentioning

confidence: 99%

Direct, Iridium‐Catalyzed Enantioselective and Regioselective Allylic Etherification with Aliphatic Alcohols

2008

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“…[11] The decarboxylation reaction can be conducted under an eutral condition to avoid decomposition of the ketone, because the carbanion is generated in situ by releasing CO 2 withouta na dditional base to activate the nucleophile. [12] Furthermore, our decarboxylation strategy is au nimolecular process after complexation between the substrate and catalyst, which in principle puts an enolatea nd an acetylide on the metal-givingi ntermediate B without a transmetalation step to preventd isproportionation. Herein, we disclose palladium-catalyzed decarboxylative alkynylation triggered by C(sp 3 )ÀObond cleavage of a-acyloxyketone.…”

mentioning

confidence: 99%

Palladium‐Catalyzed Decarboxylative Alkynylation of α‐Acyloxyketones by C(sp³)−O Bond Cleavage

Doi

Yabuta

Sato

2019

Chemistry A European J

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Palladium‐catalyzed decarboxylative alkynylation of α‐acyloxyketones triggered by C(sp3)−O bond cleavage is disclosed. The decarboxylation strategy featuring a neutral reaction condition enabled an unprecedent catalytic alkynylation of a ketone enolate. The reaction was applied to a variety of substrates, giving desired products in good yields. We successfully obtained X‐ray crystallography of a new palladium–enolate intermediate that was synthesized by a reaction of [Pd(cod)(CH2TMS)2] with XPhos and α‐acyloxyketone at room temperature, indicating facile C(sp3)−O bond disconnection.

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“…To avoid the stoichiometric use of chromium, we employed a direct arylation of benzylic C(sp 3 )–H bonds using 2-azaallyl anions. [15] This strategy, introduced by Oshima and co-workers [16] and rendered synthetically useful by Buchwald’s group [17] and by us, [18] takes advantage of the stability of 2-azaallyl anions (Scheme 1b). …”

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confidence: 99%

Palladium‐Catalyzed C(sp³)H Arylation of N‐Boc Benzylalkylamines via a Deprotonative Cross‐Coupling Process

Hussain

Kim

Walsh

2015

Chemistry A European J

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Diarylmethylamines are key intermediates and products in the pharmaceutical industry. Herein we disclose a novel method toward the synthesis of these important compounds via C–H functionalization. Presented is a reversible deprotonation of N-Boc benzylalkylamines at the benzylic C–H with in situ arylation by a NiXant-Phos-based palladium catalyst (50–93% yield, 29 examples). The method is also successful with N-Boc-tetrahydroisoquinolines. The advantages of this method are it avoids strong bases, low temperatures, and the need to transmetallate to main group metals for the coupling.

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Transition Metal Catalyzed Decarboxylative Additions of Enolates

Cited by 161 publications

References 49 publications

Direct, Iridium‐Catalyzed Enantioselective and Regioselective Allylic Etherification with Aliphatic Alcohols

Direct, Iridium‐Catalyzed Enantioselective and Regioselective Allylic Etherification with Aliphatic Alcohols

Palladium‐Catalyzed Decarboxylative Alkynylation of α‐Acyloxyketones by C(sp³)−O Bond Cleavage

Palladium‐Catalyzed C(sp³)H Arylation of N‐Boc Benzylalkylamines via a Deprotonative Cross‐Coupling Process

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Transition Metal Catalyzed Decarboxylative Additions of Enolates

Cited by 161 publications

References 49 publications

Direct, Iridium‐Catalyzed Enantioselective and Regioselective Allylic Etherification with Aliphatic Alcohols

Direct, Iridium‐Catalyzed Enantioselective and Regioselective Allylic Etherification with Aliphatic Alcohols

Palladium‐Catalyzed Decarboxylative Alkynylation of α‐Acyloxyketones by C(sp3)−O Bond Cleavage

Palladium‐Catalyzed C(sp3)H Arylation of N‐Boc Benzylalkylamines via a Deprotonative Cross‐Coupling Process

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Product

Resources

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Palladium‐Catalyzed Decarboxylative Alkynylation of α‐Acyloxyketones by C(sp³)−O Bond Cleavage

Palladium‐Catalyzed C(sp³)H Arylation of N‐Boc Benzylalkylamines via a Deprotonative Cross‐Coupling Process