Alkyne Hydroheteroarylation: Enantioselective Coupling of Indoles and Alkynes via Rh-Hydride Catalysis

Journal of the American Chemical Society, Journal Year: 2017, Volume and Issue: 139(31), P. 10641 - 10644

Published: July 25, 2017

We report an enantioselective coupling between alkynes and indoles. A Rh-hydride catalyst isomerizes to generate a metal-allyl species that can be trapped with both aromatic heteroaromatic nucleophiles.

Language: Английский

---

Catalytic Enantioselective Alkylation of Prochiral Enolates

Chemical Reviews, Journal Year: 2021, Volume and Issue: 121(15), P. 9196 - 9242

Published: July 26, 2021

The asymmetric alkylation of enolates is a particularly versatile method for the construction α-stereogenic carbonyl motifs, which are ubiquitous in synthetic chemistry. Over past several decades, focus has shifted to development new catalytic methods that depart from classical stoichiometric stereoinduction strategies (e.g., chiral auxiliaries, alkali metal amide bases, electrophiles, etc.). In this way, enantioselective prochiral greatly improves step- and redox-economy process, addition enhancing scope selectivity these reactions. review, we summarize origin advancement enolate methods, with directed emphasis on union nucleophiles carbon-centered electrophiles derivatives. Hence, transformative developments each distinct class nucleophile ketone enolates, ester etc.) presented modular format highlight state-of-the-art current limitations area.

Language: Английский

---

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

---

Generation and Application of (Diborylmethyl)zinc(II) Species: Access to Enantioenriched gem‐Diborylalkanes by an Asymmetric Allylic Substitution

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(39), P. 12930 - 12934

Published: July 2, 2018

We report the successful generation of (diborylmethyl)zinc(II) species by transmetallation beteween isolable (diborylmethyl)lithium and zinc(II) halide (X=Br, Cl) their application in synthesis enantioenriched gem-diborylalkanes bearing a stereogenic center at β-position diboryl groups an asymmetric allylic substitution reaction. The reaction has broad substrate scope, various can be obtained good yields with excellent enantioselectivity. Further elaboration provides access to diverse set valuable chiral building blocks.

Language: Английский

---

Tandem Iridium Catalysis as a General Strategy for Atroposelective Construction of Axially Chiral Styrenes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(28), P. 10686 - 10694

Published: July 6, 2021

Axially chiral styrenes are of great interest since they may serve as a class novel ligands in asymmetric synthesis. However, only recently have strategies been developed for their enantioselective preparation. Thus, the development and efficient methodologies is highly desirable. Herein, we reported first tandem iridium catalysis general strategy synthesis axially enabled by Asymmetric Allylic Substitution-Isomerization (AASI) using cinnamyl carbonate analogues electrophiles naphthols nucleophiles. In this approach, were generated through two independent iridium-catalytic cycles: iridium-catalyzed allylic substitution situ isomerization via stereospecific 1,3-hydride transfer catalyzed same catalyst. Both experimental computational studies demonstrated that proceeded benzylic C–H bond oxidative addition, followed terminal reductive elimination. Amid central-to-axial chirality transfer, hydroxyl naphthol plays crucial role ensuring stereospecificity coordinating with Ir(I) center. The process accommodated broad functional group compatibility. products excellent yields to high enantioselectivities, which could be transformed various molecules.

Language: Английский

---

Direct Asymmetric Alkylation of Ketones: Still Unconquered

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(32), P. 9278 - 9290

Published: May 12, 2017

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

Language: Английский

---

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

---

Cooperative N-heterocyclic Carbene and Iridium Catalysis Enables Stereoselective and Regiodivergent [3 + 2] and [3 + 3] Annulation Reactions

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(7), P. 3810 - 3821

Published: March 12, 2021

A cooperative N-heterocyclic carbene (NHC)/iridium catalysis has been developed to achieve highly stereoselective and regiodivergent [3 + 2] 3] annulation reactions of 2-indolyl allyl carbonates with enals. The use the NHC catalyst introduced switchable homoenolate enolate intermediates from common enal precursor via a simple adjustment reaction conditions in predictable manner. This protocol furnishes two types biologically important products, pyrrolo[1,2-a]indoles pyridine[1,2-a]indoles, high diastereo- enantioselectivities (up >20:1 dr >99% ee). Notably, all four stereoisomers these products vicinal stereocenters could be afforded through permutations enantiomers chiral catalysts. Mechanistic investigations further computational density functional theory calculations give an explanation origin regioselectivity. In addition, NHC-enolate intermediate generated formylcyclopropanes was also compatible this catalytic system thus arsenal optically pure pyrrolo[1,2-a]indole enriched.

Language: Английский

---

Regiodivergent Hydroaminoalkylation of Alkynes and Allenes by a Combined Rhodium and Photoredox Catalytic System

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(11), P. 3392 - 3397

Published: Jan. 9, 2019

Abstract A rhodium/photoredox dual catalyzed regiodivergent α‐allylation of amines is described. As an atom‐economic and efficient method, alkynes allenes are used as allylic electrophile surrogates in this novel protocol. With different reaction conditions, synthetically useful branched or linear homoallylic could be synthesized good to excellent yields regioselectivity. This straightforward strategy complements the traditional transition‐metal allylation reactions.

Language: Английский

---

Mechanistic Study of Ni and Cu Dual Catalyst for Asymmetric C–C Bond Formation; Asymmetric Coupling of 1,3-Dienes with C-nucleophiles to Construct Vicinal Stereocenters

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(11), P. 6643 - 6655

Published: May 21, 2021

We report details of the reaction mechanism for a coupling 1,3-dienes with C-nucleophiles that was catalyzed by Ni/Cu cooperative catalyst system using Ni(cod)2 and [Cu(CH3CN)4]PF6 in presence chiral JOSIPHOS-type bisphosphine ligand iPr2NEt, providing direct access to highly valuable vicinal quaternary tertiary stereocenters high enantio- diastereoselectivity. The bimetallic exhibited broad substrate scope, including both cyclic/acyclic stabilized nucleophiles aryl-/alkyl-substituted 1,3-dienes. elucidated depth isolating characterizing four key complexes nickel copper conducting deuterium labeling experiments, kinetic studies, density functional theory calculations. turnover-limiting step this is proton-transfer diene-coordinated Ni complex 6 from cationic Cu 8 yield π-allyl 7 enolate 9, respectively. stereoselectivity also clarified according single-point calculations intermediates 9.

Language: Английский

---