Enantioselective Synthesis of Chiral Cyclobutenes Enabled by Brønsted Acid-Catalyzed Isomerization of BCBs

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(39), P. 21152 - 21158

Published: Sept. 21, 2023

Chiral cyclobutene units are commonly found in natural products and biologically active molecules. Transition-metal-catalysis has been extensively used asymmetric synthesis of such structures, while organocatalytic approaches remain elusive. In this study, bicyclo[1.1.0]butanes involved enantioselective transformation for the first time to offer a highly efficient route toward cyclobutenes with good regio- enantiocontrol. The utilization N-triflyl phosphoramide as chiral Brønsted acid promoter enables isomerization process proceed under mild conditions low catalyst loading well functional group compatibility. resulting could serve platform molecules downstream manipulations excellent reservation stereochemical integrity, demonstrating synthetic practicality developed method. Control experiments have also performed verify formation key carbocation intermediate at benzylic position.

Language: Английский

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B(C₆F₅)₃-Catalyzed Dehydrogenation of Pyrrolidines to Form Pyrroles

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(7), P. 4856 - 4864

Published: March 18, 2024

Pyrroles are important N-heterocycles found in medicines and materials. The formation of pyrroles from widely accessible pyrrolidines is a potentially attractive strategy but an underdeveloped approach due to the sensitivity oxidative conditions required achieve such transformation. Herein, we report catalytic that employs commercially available B(C6F5)3 operationally simple procedure allows serve as direct synthons for pyrroles. Mechanistic studies have revealed insights into borane-catalyzed dehydrogenative processes.

Language: Английский

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Diastereo- and Enantioselective Synthesis of Eight-Membered Heterocycles via an Allylation/Ring Expansion Sequence Enabled by Multiple Catalysis

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(20), P. 12557 - 12564

Published: Sept. 29, 2021

The development of protocols for constructing chiral medium-sized heterocycles with high efficiency and excellent stereocontrol is great interest owing to their ubiquitous occurrence in natural products biologically active pharmaceuticals. Nonetheless, current synthetic approaches are limited due unfavorable enthalpy entropy factors, as well transannular interactions. present work addresses this issue by designing an asymmetric allylation/ring expansion reaction 2-(1-hydroxyallyl)phenols cyclobutanone carboxamides enabled sequential iridium/zinc/bifunctional squaramide catalysis, affording a series 8-membered benzo[b]oxocines yields diastereo- enantioselectivities. Mechanistic investigation reveals that the enantioselectivity controlled iridium catalyst, while density functional theory calculations demonstrate diastereoselectivity bifunctional catalyst. Moreover, allylation strategy demonstrated be also applicable synthesis two types enantiomerically enriched nitrogen heterocycles, benzo[b]azocines polycyclic cyclobuta[b]quinolines.

Language: Английский

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Pd/Cu-Catalyzed Synthesis of Internal and Sila-Ynones by Direct Selective Acyl Sonogashira Cross-Coupling of Carboxylic Acids with Terminal Alkynes

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(9), P. 5819 - 5827

Published: April 13, 2023

The direct acyl Sonogashira cross-coupling of carboxylic acids with terminal alkynes has been achieved through Pd/Cu cooperative catalysis. In this reaction, the readily available act as source for coupling various to produce highly valuable ynones in good high yields. reaction features chemoselectivity and functional group tolerance. offers access versatile silyl-ynones. late-stage modification bioactive molecules gram-scale experiments highlight synthetic value organic synthesis. method enables preparation directly from absence C(acyl)–C(sp) decarbonylation.

Language: Английский

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Enantioselective [2+2] Cycloaddition of Allenyl Imide with Mono‐ or Disubstituted Alkenes

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(44)

Published: Sept. 14, 2022

Abstract An efficient catalytic asymmetric [2+2] cycloaddition of allenyl imide and mono‐ or disubstituted alkenes is disclosed. The key feature this method the use bidentate weakly activated less steric hindered alkene pair by utilizing chiral magnesium(II) complex N , N′ ‐dioxide, which could provide through‐space dispersion interactions to orientate arrangement alkene. This protocol allows generation a series axially cyclobutenes four‐membered ring‐containing spirocycles (80 examples) in high yield (up 99 %) with excellent enantioselectivity >99 % ee ), late‐stage modification biologically active molecules as well. Experimental studies DFT calculations revealed that proceeded via stepwise mechanism involving short‐lived zwitterionic intermediate. π‐π interaction between amide moiety ligand was crucial for enantiocontrol.

Language: Английский

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Borane-Catalyzed Enantioselective α-Alkylation of Unactivated 2-Alkylbenzoxazoles with Electron-Deficient Olefins

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(35), P. 24663 - 24669

Published: Aug. 20, 2024

Chiral borane–catalyzed reactions have recently emerged as a powerful tool for the enantioselective production of chiral scaffolds. In this study, we demonstrated first time that bisborane catalyst can be used α-functionalization 2-alkylazaarenes; specifically, accomplished unprecedented highly α-alkylation unactivated 2-alkylbenzoxazoles with electron-deficient olefins. The strong Lewis acidity and steric bulk were essential to observed reactivity selectivity.

Language: Английский

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Borane/Gold(I)‐Catalyzed C−H Functionalization Reactions and Cycloaddition Reactions of Amines and α‐Alkynylenones

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(35)

Published: July 4, 2022

Abstract We designed a borane/gold(I) co‐catalytic system and used it for C−H functionalization reactions cycloaddition between tertiary amines α‐alkynylenones. Both effectively incorporated furan ring into the amine.

Language: Английский

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Recent Advances in Asymmetric Catalysis Using p‐Block Elements

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 63(9)

Published: Dec. 1, 2023

The development of new methods for enantioselective reactions that generate stereogenic centres within molecules are a cornerstone organic synthesis. Typically, metal catalysts bearing chiral ligands as well organocatalysts have been employed the synthesis compounds. In this review, we highlight recent advances in main group catalysis using p-block elements (boron, aluminium, phosphorus, bismuth) complementary and sustainable approach to molecules. Several these benefit terms high abundance, low toxicity, selectivity, excellent reactivity. This minireview summarises utilisation element asymmetric value-added

Language: Английский

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Lewis Acid‐Driven Inverse Hydride Shuttle Catalysis

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(27)

Published: March 29, 2024

Abstract Inverse hydride shuttle catalysis provides a multicomponent platform for the highly efficient synthesis of alkaloid frameworks with exquisite diastereoselectivity. However, number limitations hinder this method, primarily strict requirement electron‐deficient acceptors. Herein, we present general Lewis acid‐driven approach to address constraint, and have developed two broad strategies enabling modular complex azabicycles that were entirely unattainable using previous method. The enhanced synthetic flexibility facilitates streamlined asymmetric cyclization, leading concise total (−)‐tashiromine.

Language: Английский

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Sc-Catalyzed Asymmetric [2 + 2] Annulation of 2-Alkynylnaphthols with Dienes to Access Cyclobutene Frameworks

Organic Letters, Journal Year: 2025, Volume and Issue: 27(4), P. 1006 - 1011

Published: Jan. 16, 2025

Herein, we introduce a scandium-catalyzed synthetic strategy that provides access to diverse and functionalized array of cyclobutene frameworks adorned with quaternary carbon center. This approach broadens the repertoire 2-alkynylnaphthols alkenes, offering versatile platform for construction complex molecular architectures. The asymmetric catalytic [2 + 2] cycloaddition reaction demonstrates wide substrate scope an impressive functional group tolerance, yielding products high efficiency, up 97% yield, excellent enantiomeric excess 97%. simplicity scaling this process, coupled ease converting these into variety substituted products, significantly enhances utility method.

Language: Английский

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