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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Catalytic Prenylation and Reverse Prenylation of Indoles with Isoprene: Regioselectivity Manipulation through Choice of Metal Hydride

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(16), P. 5438 - 5442

Published: Feb. 12, 2019

The basic industrial feedstock isoprene was employed as a building block to install prenyl and reverse-prenyl groups onto indoles. regioselectivity can be manipulated by the choice of metal hydride. Reverse-prenylated indoles were attained with high selectivity when using Rh-H. By switching Pd-H catalyst, toward prenylated achieved. This regiodivergent method also features atom economy without stoichiometric byproduct formation.

Language: Английский

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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

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Enantioselective Addition of Pyrazoles to Dienes**

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(36), P. 19660 - 19664

Published: June 19, 2021

We report the first enantioselective addition of pyrazoles to 1,3-dienes. Secondary and tertiary allylic can be generated with excellent regioselectivity. Mechanistic studies support a pathway distinct from previous hydroaminations: Pd

Language: Английский

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Cobalt‐Catalyzed Asymmetric Alkylation of (Hetero)Arenes with Styrenes

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(26)

Published: April 1, 2022

An efficient and general intermolecular Cobalt(II)-catalyzed asymmetric alkylation of styrenes with (hetero)arenes including indoles, thiophene electron rich arenes has been developed, providing straightforward access to enantioenriched alkyl(hetero)arenes high enantioselectivity. Mechanistic studies suggest that the reaction underwent a CoH-mediated hydrogen atom transfer (HAT) alkenes, followed by pivotal catalyst-controlled SN 2-like pathway between in situ generated organocobalt(IV) species aromatic nucleophiles. This is first CoH-catalyzed hydrofunctionalization using carbon nucleophiles, new strategy for Friedel-Crafts type alkylation.

Language: Английский

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Hydroaminoalkylation for the Catalytic Addition of Amines to Alkenes or Alkynes: Diverse Mechanisms Enable Diverse Substrate Scope

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(26), P. 11459 - 11481

Published: June 22, 2022

Hydroaminoalkylation is a powerful, atom-economic catalytic reaction for the of amines with alkenes and alkynes. This C–H functionalization allows alkylation using simple or alkynes as alkylating agents. transformation has significant potential transformative approaches in pharmaceutical, agrochemical, fine chemical industries preparation selectively substituted N-heterocycles shows promise materials science synthesis functional responsive aminated materials. Different early transition-metal, late photoredox catalysts mediate hydroaminoalkylation by distinct mechanistic pathways. These insights have resulted development new conditions to realize broad range substrates: activated unactivated, terminal internal, C–C double triple bonds aryl alkyl primary, secondary, tertiary amines, including N-heterocyclic amines. By deploying select specific substrate combinations, control over regioselectivity, diastereoselectivity, enantioselectivity been realized. Key barriers widespread adoption this include air moisture sensitivity transition-metal well heavy dependence on amine protecting directing groups photocatalytic routes. Advances improved catalyst robustness, scope, regio-/stereoselective reactions early- catalysts, catalysis, are highlighted, opportunities further included. perspective that be disruptive strategy from alkenes.

Language: Английский

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Rhodium‐Catalyzed Enantio‐ and Regioselective Allylation of Indoles with gem‐Difluorinated Cyclopropanes

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(22)

Published: March 22, 2024

Abstract The use of gem ‐difluorinated cyclopropanes ( ‐DFCPs) as fluoroallyl surrogates under transition‐metal catalysis has drawn considerable attention recently but such reactions are restricted to producing achiral or racemic mono‐fluoroalkenes. Herein, we report the first enantioselective allylation indoles rhodium with ‐DFCPs. This reaction shows exceptional branched regioselectivity towards ‐DFCPs, which provides an efficient route enantioenriched fluoroallylated wide substrate scope and good functional group tolerance.

Language: Английский

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Regio- and Enantioselective Rhodium-Catalyzed Allylic Alkylation of Racemic Allylic Alcohols with 1,3-Diketones

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(24), P. 7737 - 7742

Published: May 25, 2018

Highly regio- and enantioselective rhodium-catalyzed allylic alkylation of 1,3-diketones with racemic secondary alcohols is reported. In the presence a Rh-catalyst derived from Carreira (P, olefin)-ligand TFA as an additive, chiral branched α-allylated could be obtained in good to excellent yields, enantioselectivity (b/l > 19/1, 86–98% ee). The direct utilization allyl electrophiles represents improvement viewpoint atom economy. Both aryl- aliphatic-substituted are suitable substrates reaction outcomes. This features mild conditions, broad substrate scope, readily available substrates.

Language: Английский

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Chemo-, Regio-, and Enantioselective Rhodium-Catalyzed Allylation of Triazoles with Internal Alkynes and Terminal Allenes

Organic Letters, Journal Year: 2018, Volume and Issue: 20(3), P. 598 - 601

Published: Jan. 19, 2018

The rhodium-catalyzed asymmetric N1-selective and regioselective coupling of triazole derivatives with internal alkynes terminal allenes gives access to secondary tertiary allylic triazoles in very good enantioselectivities. For this process, three new members the JosPOphos ligand family have been prepared employed catalysis. optimized reaction conditions enable as well allenes, displaying a high tolerance for functional groups. A gram scale provided N1-allyltriazole, which was subjected various transformations highlighting synthetic utility.

Language: Английский

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Enantioselective Synthesis of Functionalized Arenes by Nickel‐Catalyzed Site‐Selective Hydroarylation of 1,3‐Dienes with Aryl Boronates

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(33), P. 14070 - 14075

Published: May 6, 2020

A catalytic method for the site-selective and enantioselective synthesis of functionalized arenes by intermolecular hydroarylation terminal internal 1,3-dienes with aryl pinacolato boronates is reported. The reactions are promoted 5.0 mol % a readily available monodentate phosphoramidite-Ni complex in ethanol, affording variety enantioenriched products up to 96 yield 99:1 er. Mechanistic studies indicate that Ni-allyl formation irreversible related nature arylboronate.

Language: Английский

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