Iridium-Catalyzed Diastereo-, Enantio-, and Regioselective Allylic Alkylation with Prochiral Enolates

Hethcox, J. Caleb; Shockley, Samantha E.; Stoltz, Brian M.

doi:10.1021/acscatal.6b01886

Cited by 173 publications

(43 citation statements)

References 35 publications

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“…Thef ormation of a-allylated ketones,e specially those bearing quaternary centers,v ia palladium catalysis has been well documented over the last 20 years. [21] Thew ell-known Tsuji allylation involves the Pd 0 mediated decarboxylation of allyl b-ketoesters,o rt he use of enol derivatives. [22] The enantioselective version of the Tsuji allylation was reported by Stoltz two decades later (Scheme 6).…”

Section: Metal-based Catalytic Methodsmentioning

confidence: 99%

Direct Asymmetric Alkylation of Ketones: Still Unconquered

2017

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The alkylation of ketones is taught at basic undergraduate level. In many cases this transformation leads to the formation of a new stereogenic center. However, the apparent simplicity of the transformation is belied by a number of problems. So much so, that a general method for the direct asymmetric alkylation of ketones remains an unmet target. Despite the advancement of organocatalysis and transition-metal catalysis, neither field has provided an adequate solution. Indeed, even use of an efficient and general stoichiometric chiral reagent has yet to be reported. Herein we describe the state-of-the-art in terms of direct alkylation reactions of some carbonyl groups. We outline the limited progress that has been made with ketones, and potential routes towards ultimately achieving a widely applicable methodology for the asymmetric alkylation of ketones.

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Section: Metal-based Catalytic Methodsmentioning

confidence: 99%

Direct Asymmetric Alkylation of Ketones: Still Unconquered

2017

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“…[1] Within this area, our group has invested considerably in the development of cooperative isothiourea/palladium catalysis as ageneral platform by which to control enantioselective carbon-carbon bond formation using challenging acyclicp rochiral ester pronucleophiles. [2] Our efforts have established C1-ammonium enolates as effective nucleophiles for cationic p(allyl)Pd electrophiles,w here the activity and reactivity of the Pd center can be modulated via the ancillary ligands without compromising the level of enantiocontrol. [3] This mechanistic regime is general such that C1-ammonium enolates also undergo efficient stereocontrolled reaction with other catalytically accessible electrophiles.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Syntheses of Strychnos and Chelidonium Alkaloids through Regio‐ and Stereocontrolled Cooperative Catalysis

et al. 2020

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We describe enantioselective syntheses of strychnos and chelidonium alkaloids. In the first case, indole acetic acid esters were established as excellent partner nucleophiles for enantioselective cooperative isothiourea/Pd catalyzed α‐alkylation. This provides products containing indole‐bearing stereocenters in high yield and with excellent levels of enantioinduction in a manner that is notably independent of the N‐substituent. This led to concise syntheses of (−)‐akuammicine and (−)‐strychnine. In the second case, the poor performance of ortho‐substituted cinnamyl electrophiles in the enantioselective cooperative isothiourea/Ir catalyzed α‐alkylation was overcome by appropriate substituent choice, leading to enantioselective syntheses of (+)‐chelidonine, (+)‐norchelidonine, and (+)‐chelamine.

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“…[1] Ther eactions involving prochiral nucleophiles provide an effective and reliable strategy for the synthesis of molecules containing vicinal stereocenters.H owever,m ost of the reported reactions only afforded products in one of two possible relative configurations (syn or anti). [2] Available methods for accessing all four possible stereoisomers are relatively limited. [3] A great breakthrough in this field was made by Carreira and coworkers,w ho introduced an ingenious stereodivergent dual catalysis strategy in 2013 (Scheme 1a).…”

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confidence: 99%

Sequence‐Dependent Stereodivergent Allylic Alkylation/Fluorination of Acyclic Ketones

et al. 2019

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The stereodivergent iridium-catalyzed allylic alkylation and fluorination of acyclic ketones is described. a-Pyridyl-a-fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities.D istinct from knowns tereodivergent synthesis,f or whicht wo different chiral catalysts are required in general, herein we report as equence-dependent stereodivergent synthesis.W itho nly as ingle chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric allylic alkylation and fluorination and varying the absolute configuration of the Ir catalyst.

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Iridium-Catalyzed Diastereo-, Enantio-, and Regioselective Allylic Alkylation with Prochiral Enolates

Cited by 173 publications

References 35 publications

Direct Asymmetric Alkylation of Ketones: Still Unconquered

Direct Asymmetric Alkylation of Ketones: Still Unconquered

Enantioselective Syntheses of Strychnos and Chelidonium Alkaloids through Regio‐ and Stereocontrolled Cooperative Catalysis

Sequence‐Dependent Stereodivergent Allylic Alkylation/Fluorination of Acyclic Ketones

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