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

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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

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Cooperative Tertiary Amine/Chiral Iridium Complex Catalyzed Asymmetric [4+3] and [3+3] Annulation Reactions

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(42), P. 15021 - 15025

Published: Aug. 15, 2019

Abstract Asymmetric reactions merging organocatalysis and metal catalysis significantly broaden the scope of organic synthesis. Nevertheless, accomplishment stereoselective annulations combining two types dipole species, independently generated from activations organocatalysts complexes, still remains as a challenging task. Now, Morita–Baylis–Hillman carbonates isatins carbamate‐functionalized allyl could be chemoselectively activated by achiral Lewis basic tertiary amines chiral iridium complexes. The zwitterionic allylic ylides 1,4‐π‐allyliridium dipoles formed in situ are assembled highly [4+3] annulation pattern. Similar cooperative catalytic strategy applied for vinyl aziridines, furnishing an asymmetric [3+3] reaction also with excellent stereocontrol.

Language: Английский

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Regio‐ and Enantioselective Synthesis of Sulfone‐Bearing Quaternary Carbon Stereocenters by Pd‐Catalyzed Allylic Substitution

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(3), P. 1340 - 1345

Published: Sept. 10, 2019

Abstract Chiral sulfones are of great importance in medicinal chemistry and chemical synthesis. Efficient methods for preparing enantiomerically enriched sulfone‐containing molecules can therefore be significant value; such methods, however, uncommon. Herein, we report the first general palladium‐catalyzed sulfonylation vinyl cyclic carbonates with sodium sulfinates. A series tertiary allylic were synthesized good yields excellent enantiomeric ratios. Both aliphatic‐ aryl‐substituted suitable reactants results. This reaction features broad substrates scope, readily available starting materials, regio‐ enantioselectivity, synthesis sulfone‐bearing quaternary carbon stereocenters. Through geranyl derived carbonate 1 h , achieve formal total (+)‐agelasidine A.

Language: Английский

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Allenylic Carbonates in Enantioselective Iridium-Catalyzed Alkylations

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(13), P. 4697 - 4704

Published: Feb. 28, 2018

An enantioconvergent C(sp3)–C(sp3) coupling between racemic allenylic electrophiles and alkylzinc reagents has been developed. Ir/(phosphoramidite,olefin) catalyst provides access to highly enantioenriched substitution products (93–99% ee) with complete regiocontrol (>50:1 rr in all cases) over the corresponding 1,3-diene isomers which are obtained predominantly when other metal catalysts emplyed. The synthetic utility of was highlighted a variety stereoselective transition metal-catalyzed difunctionalization reactions. Furthermore, combination experimental theoretical studies provide support for putative reaction mechanism wherein enantiodetermining C–C occurs via nucleophilic attack on planarized aryl butadienylium π-system that is coordinated Ir center an η2-fashion.

Language: Английский

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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

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Rh(III) and Ir(III)Cp* Complexes Provide Complementary Regioselectivity Profiles in Intermolecular Allylic C–H Amidation Reactions

ACS Catalysis, Journal Year: 2019, Volume and Issue: 9(6), P. 5474 - 5479

Published: May 8, 2019

An efficient regioselective allylic C–H amidation of mono-, di-, and trisubstituted olefins has been developed. Specifically, the combination dioxazolone reagents with RhCp* IrCp* catalysts is reported to promote reactions complementary regioselectivites those previously observed in Pd-catalyzed Ag-promoted Rh-catalyzed reactions. We report that catalyst matching substrate class essential for selective complexes are required high conversion selectivities β-alkylstyrene substrates, necessary context unactivated terminal olefins.

Language: Английский

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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

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Rh-Catalyzed Regio- and Enantioselective Allylic Phosphinylation

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(7), P. 2893 - 2898

Published: Feb. 14, 2022

Transition-metal-catalyzed branched and enantioselective allylic substitution of monosubstituted precursors with carbon, nitrogen, oxygen, sulfur, fluoride nucleophiles has been well-established. However, such a selective carbon–phosphorus bond formation not realized probably due to the catalyst deactivation by strong coordinating nature phosphinylating reagents. Herein, we report Rh-catalyzed highly regio- synthesis phosphine oxides in presence chiral bisoxazoline-phosphine ligand. The application α-hydroxylalkylphosphine keep low concentration secondary is essential for high yields. addition diphenyl phosphoric acid was found only activate alcohols but also accelerate formation.

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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