Iridium-Catalyzed Asymmetric Allylic Substitution Reactions

Chemical Reviews, Journal Year: 2018, Volume and Issue: 119(3), P. 1855 - 1969

Published: Dec. 24, 2018

In this review, we summarize the origin and advancements of iridium-catalyzed asymmetric allylic substitution reactions during past two decades. Since first report in 1997, Ir-catalyzed have attracted intense attention due to their exceptionally high regio- enantioselectivities. been significantly developed recent years many respects, including ligand development, mechanistic understanding, substrate scope, application synthesis complex functional molecules. an explicit outline ligands, mechanism, scope nucleophiles, applications is presented.

Language: Английский

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Iridium-Catalyzed Asymmetric Synthesis of Functionally Rich Molecules Enabled by (Phosphoramidite,Olefin) Ligands

Accounts of Chemical Research, Journal Year: 2019, Volume and Issue: 52(9), P. 2657 - 2672

Published: June 19, 2019

ConspectusThe catalytic, asymmetric synthesis of complex molecules has been a core focus our research program for some time because developments in the area can have an immediate impact on identification novel strategies value-added molecules. In concert with this central interest, we emphasized design ligand scaffolds as tactic to discover and develop chemistry overcome well-recognized synthetic challenges. Based group's work chiral pool-derived diolefin ligands, designed implemented class hybrid (phosphoramidite,olefin) which combines properties both phosphoramidite olefin motifs impact, fine-tune, even override inherent reactivity metal center. Specifically, utilized these unique modifying ligands address several recognized limitations field iridium-catalyzed, allylic substitution. The methods documented typically employ branched, unprotected alcohols substrates obviate need rigorous exclusion air moisture.Following Takeuchi's seminal report demonstrating high aptitude Ir(I)-phosphite catalysts branch-selective substitution, concerted efforts from numerous laboratories led broadening utility reaction class. first section Account outlines process leading discovery unprecedented its validation iridium-catalyzed amination alcohols. This continues involving heteroatom-based nucleophiles within inter- intramolecular etherification, thioetherification spiroketalization processes. second highlights use readily available carbon possessing sp, sp2, sp3 hybridization series enantioselective carbon–carbon bond-forming reactions. We describe how alkylzinc, allylsilane, classes organotrifluoroborate be coupled enantioselectively enable construction key including 1,5-dienes, 1,4-dienes, 1,4-enynes. Since electronic steric renders (η3-allyl)-Ir(III) intermediate highly electrophilic, weak such alkyl olefins used. also show that more nucleophilic alkene enamines situ generated ketene acetals smoothly participate substitution reactions yield valuable piperidines γ,δ-unsaturated esters, respectively.The concept stereodivergent dual catalysis, synergistically amine catalysis iridium furnish α-allylated aldehydes containing two independently controllable stereocenters is then discussed. enabled independent, stereoselective all four possible product stereoisomers single set starting materials, was highlighted Δ9-tetrahydrocannabinol. concludes overview organometallic mechanistic studies regarding relevant intermediates catalytic cycle These allowed us better understand origin characteristics exhibited by catalyst comparison related systems.

Language: Английский

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Sequence‐Dependent Stereodivergent Allylic Alkylation/Fluorination of Acyclic Ketones

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(5), P. 2039 - 2043

Published: Nov. 6, 2019

Abstract The stereodivergent iridium‐catalyzed allylic alkylation and fluorination of acyclic ketones is described. α‐Pyridyl‐α‐fluoroketones with vicinal tertiary quaternary stereocenters were obtained in moderate to excellent yields stereoselectivities. Distinct from known synthesis, for which two different chiral catalysts are required general, herein we report a sequence‐dependent synthesis. With only single Ir catalyst, all four possible stereoisomers the products prepared same starting materials by simply adjusting sequence asymmetric varying absolute configuration catalyst.

Language: Английский

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Catalytic Chemo- and Enantioselective Transformations of gem-Diborylalkanes and (Diborylmethyl)metallic Species

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(20), P. 3917 - 3929

Published: Oct. 6, 2021

ConspectusChemo- and stereoselective transformations of polyborylalkanes are powerful efficient methods to access optically active molecules with greater complexity diversity through programmed synthetic design. Among the various polyborylalkanes, gem-diborylalkanes have attracted much attention in organic chemistry as versatile handles. The notable advantage lies their ability generate two key intermediates, α-borylalkyl anions (gem-diborylalkyl) anions. These different intermediates can be applied enantioselective reactions rapidly a diverse set enantioenriched organoboron compounds, which further manipulated chiral molecule libraries via stereospecific C(sp3)–B bond transformations.In this Account, we summarize our recent contributions development catalytic chemo- using nucleophiles, categorized follows: (1) copper-catalyzed coupling electrophiles (2) design synthesis (diborylmethyl)metallic species applications reactions. Since Shibata Endo reported Pd-catalyzed chemoselective Suzuki–Miyaura cross-coupling organohalides 2014, Morken Hall subsequently developed first analogous TADDOL-derived phosphoramidite supporting ligand palladium catalyst. This discovery sparked interest electrophiles. Our initial studies focused on generating (α-borylmethyl)copper by enantiotopic-group-selective transmetalation copper complexes aldimines ketimines afford syn-β-aminoboronate esters excellent enantio- diastereoselectivity. Moreover, allylation that proceeded reaction situ-generated (α-borylalkyl)copper allyl bromides. Mechanistic investigations revealed between complex occurred open transition state rather than closed state, thereby effectively species. We also utilized such (diborylmethyl)silanes (diborylmethyl)zinc halides succeeded developing aryl iodides benzylic 1,1-silylboronate esters, could used for consecutive molecules. In addition, synthesized time isolated (diborylmethyl)lithium zinc(II) utilization bearing center at β-position an iridium-catalyzed allylic substitution process. addition research efforts, include other groups. hope Account will draw community gem-diboryl compounds provide guiding principles future compounds.

Language: Английский

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Versatile cobalt-catalyzed regioselective chain-walking double hydroboration of 1,n-dienes to access gem-bis(boryl)alkanes

Nature Communications, Journal Year: 2020, Volume and Issue: 11(1)

Published: Feb. 7, 2020

Abstract Double hydroboration of dienes is the addition a hydrogen and boryl group to two double bonds diene molecule represents straightforward effective protocol prepare synthetically versatile bis(boryl)alkanes, provided that this reaction occurs selectively. However, can potentially yield several isomeric organoboron products, it still remains challenge control regioselectivity reaction, which allows selective production single product, in particular, for broad scope dienes. By employing readily available cobalt catalyst, here we show yields useful gem -bis(boryl)alkanes with excellent regioselectivity. In addition, encompasses wide range conjugated non-conjugated Furthermore, mechanistic studies indicate cobalt-catalyzed through boryl-directed chain-walking alkenylboronates generated from anti -Markovnikov 1,2-hydroboration 1,n-diene.

Language: Английский

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α-Boryl Organometallic Reagents in Catalytic Asymmetric Synthesis

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(16), P. 10660 - 10680

Published: Aug. 12, 2021

Recent years have witnessed an increase in the popularity of α-boryl organometallic reagents as versatile nucleophiles asymmetric synthesis. These compounds been adopted chemo- and stereoselective coupling reactions with a number different electrophiles. The resulting enantioenriched boronic esters can be applied stereospecific carbon-carbon or carbon-heteroatom bond construction reactions, enabling two-step strategy for complex structures high efficiency functional group compatibility. Due to these reasons, tremendous effort has devoted preparation enantiomerically enriched development related racemic prochiral materials. In this review, we describe enantio- diastereoselective that involve starting materials products showcase their synthetic utility.

Language: Английский

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Enantioselective Allylation of Alkenyl Boronates Promotes a 1,2-Metalate Rearrangement with 1,3-Diastereocontrol

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(13), P. 4921 - 4927

Published: March 23, 2021

Alkenyl boronates add to Ir(π-allyl) intermediates with high enantioselectivity. A 1,2-metalate shift forms a second C–C bond and sets 1,3-stereochemical relationship. The three-component coupling provides tertiary boronic esters that can undergo multiple additional functionalizations. An extension trisubstituted olefins three contiguous stereocenters.

Language: Английский

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Recent advances in iridium-catalyzed enantioselective allylic substitution using phosphoramidite-alkene ligands

Catalysis Science & Technology, Journal Year: 2022, Volume and Issue: 12(13), P. 4100 - 4112

Published: Jan. 1, 2022

This minireview describes the recent progress of iridium-catalyzed enantioselective allylic substitution using phosphoramidite-alkene ligands realizing highly carbon–carbon and carbon–heteroatom bond formation.

Language: Английский

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Diborylmethyl Group as a Transformable Building Block for the Diversification of Nitrogen‐Containing Molecules

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(37)

Published: July 18, 2022

Abstract The development of new approaches to installing diverse carbon fragments a nitrogen atom has attracted considerable attention in chemical science. While numerous strategies have been devised forge C(sp 3 )−N bonds, one conceptually powerful and straightforward approach is insert transformable sp ‐carbon unit onto for modular diversification. Here we describe the successful synthesis halo‐diborylmethanes their applications preparation nitrogen‐substituted diborylmethanes through homologative coupling with variety nucleophiles including biologically relevant molecules. This process exhibits remarkably broad substrate scope, usefulness obtained compounds demonstrated by diversification diborylmethyl group access various nitrogen‐containing

Language: Английский

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Dynamic kinetic asymmetric arylation and alkenylation of ketones

Science, Journal Year: 2023, Volume and Issue: 379(6633), P. 662 - 670

Published: Feb. 16, 2023

Despite the importance of enantioenriched alcohols in medicinal chemistry, total synthesis, and materials science, efficient selective construction tertiary bearing two contiguous stereocenters has remained a substantial challenge. We report platform for their preparation through enantioconvergent, nickel-catalyzed addition organoboronates to racemic, nonactivated ketones. prepared several important classes α,β-chiral single step with high levels diastereo- enantioselectivity dynamic kinetic asymmetric aryl alkenyl nucleophiles. applied this protocol modify profen drugs rapidly synthesize biologically relevant molecules. expect nickel-catalyzed, base-free ketone racemization process be widely applicable strategy development processes.

Language: Английский

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