Multiplicative enhancement of stereoenrichment by a single catalyst for deracemization of alcohols

Science, Год журнала: 2023, Номер 382(6669), С. 458 - 464

Опубликована: Окт. 26, 2023

Stereochemical enrichment of a racemic mixture by deracemization must overcome unfavorable entropic effects as well the principle microscopic reversibility; recently, photochemical reaction pathways unveiled energetic input light have led to innovations toward this end, most often ablation stereogenic C(sp3)-H bond. We report photochemically driven protocol in which single chiral catalyst two mechanistically different steps, C-C bond cleavage and formation, achieve multiplicative enhancement stereoinduction, leads high levels stereoselectivity. Ligand-to-metal charge transfer excitation titanium coordinated phosphoric acid or bisoxazoline efficiently enriches alcohols that feature adjacent fully substituted centers enantiomeric ratios up 99:1. Mechanistic investigations support pathway sequential radical-mediated scission formation through common prochiral intermediate reveal that, although overall stereoenrichment is high, selectivity each individual step moderate.

Язык: Английский

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Photocatalyzed Enantioselective Functionalization of C(sp³)–H Bonds

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(2), С. 1209 - 1223

Опубликована: Янв. 3, 2024

Owing to its diverse activation processes including single-electron transfer (SET) and hydrogen-atom (HAT), visible-light photocatalysis has emerged as a sustainable efficient platform for organic synthesis. These provide powerful avenue the direct functionalization of C(sp3)–H bonds under mild conditions. Over past decade, there have been remarkable advances in enantioselective bond via combined with conventional asymmetric catalysis. Herein, we summarize involving discuss two main pathways this emerging field: (a) SET-driven carbocation intermediates are followed by stereospecific nucleophile attacks; (b) photodriven alkyl radical further enantioselectively captured (i) chiral π-SOMOphile reagents, (ii) stereoselective transition-metal complexes, (iii) another distinct stereoscopic species. We aim key reaction design, catalyst development, mechanistic understanding, new insights into rapidly evolving area research.

Язык: Английский

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Catalytic Photochemical Deracemization via Short‐Lived Intermediates

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(50)

Опубликована: Июль 10, 2023

Upon irradiation in the presence of a suitable chiral catalyst, racemic compound mixtures can be converted into enantiomerically pure compounds with same constitution. The process is called photochemical deracemization and involves formation short-lived intermediates. By opening different reaction channels for forward to intermediate re-constitution molecule, entropically disfavored becomes feasible. Since discovery first 2018, field has been growing rapidly. This review comprehensively covers research performed area discusses current developments. It subdivided according mode action respective substrate classes. focus this on scope individual reactions discussion mechanistic details underlying presented reaction.

Язык: Английский

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Enantioselective [2 + 2] Photocycloreversion Enables De Novo Deracemization Synthesis of Cyclobutanes

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(32), С. 22840 - 22849

Опубликована: Авг. 2, 2024

While photochemical deracemization significantly enhances atom economy by eliminating the necessity for additional oxidants or reductants, laborious presynthesis of substrates from feedstock chemicals is often required, thereby compromising practicality this method. In study, we propose a novel approach known as de novo synthesis, which involves direct utilization simple undergoing both transformation and reversible transformation. The efficient enantiocontrol chiral catalysts in latter process establishes an effective platform deracemization. This alternative practical to address challenges asymmetric photocatalysis has been successfully demonstrated photosensitized synthesis azaarene-functionalized cyclobutanes featuring three stereocenters, including all-carbon quaternary center. By exclusively employing suitable catalyst enable kinetically controlled [2 + 2] photocycloreversion, pave creative path toward achieving more cost-effective

Язык: Английский

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Photoexcited Palladium-Catalyzed Deracemization of Allenes

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(30), С. 21137 - 21146

Опубликована: Июль 18, 2024

The different enantiomers of specific chiral molecules frequently exhibit disparate biological, physiological, or pharmacological properties. Therefore, the efficient synthesis single is particular importance not only to pharmaceutical sector but also other industrial sectors, such as agrochemical and fine chemical industries. Deracemization, a process during which racemic mixture converted into nonracemic product with 100% atom economy theoretical yield, most straightforward method access enantioenriched challenging task due decrease in entropy microscopic reversibility. Axially allenes bear distinctive structure two orthogonal cumulative π-systems are acknowledged synthetically versatile synthons organic synthesis. selective creation axially high optical purity under mild reaction conditions has always been very popular hot topic remains challenging. Herein, photoexcited palladium-catalyzed deracemization nonprefunctionalized disubstituted disclosed. This provides an economical strategy accommodate broad scope good enantioselectivities yields (53 examples, up 96% yield 95% ee). use suitable palladium complex visible light irradiation essential factor achieving this transformation. A metal-to-ligand charge transfer mechanism was proposed based on control experiments density functional theory calculations. Quantum mechanical studies implicate dual modes asymmetric induction behind our new protocol: (1) sterically controlled stereoselective binding one allene enantiomer ground-state (2) facile, noncovalent interaction-driven excited-state isomerization toward opposite enantiomer. success newly established photochemical should provide inspiration for expansion multisubstituted will open mode enantioselective catalysis.

Язык: Английский

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Lewis Base-Catalyzed Dynamic Kinetic Asymmetric Transformation of Racemic Chlorosilanes en Route to Si-Stereogenic Silylethers

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(33), С. 23092 - 23102

Опубликована: Авг. 7, 2024

Enantiopure Si-stereogenic organosilanes are highly valued in the fields of organic synthesis, development advanced materials, and drug discovery. However, they not naturally occurring, their synthesis has been largely confined to resolution racemic silanes or desymmetrization symmetric silanes. In contrast, dynamic kinetic asymmetric transformation (DYKAT) offers a mechanistically distinct approach would broaden accessibility an enantioconvergent manner. this study, we report Lewis base-catalyzed DYKAT chlorosilanes. The chiral isothiourea catalyst, (S)-benzotetramisole, facilitates silyletherification with phenols, yielding (R)-silylethers good yields high enantioselectivity (27 examples, up 86% yield, 98:2 er). Kinetic analysis, control experiments, DFT calculations suggest that two-catalyst-bound pentacoordinate silicate is responsible for Si-configurational epimerization ion-paired tetracoordinated silicon intermediates.

Язык: Английский

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Catalytic asymmetric photocycloaddition reactions mediated by enantioselective radical approaches

Chemical Society Reviews, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

The use of olefins in the construction cyclic compounds represents a powerful strategy for advancing pharmaceutical industry.

Язык: Английский

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Photoinduced copper-catalysed deracemization of alkyl halides

Nature, Год журнала: 2025, Номер 640(8057), С. 107 - 113

Опубликована: Апрель 2, 2025

Язык: Английский

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Enantioselective organocatalytic strategies to access noncanonical α-amino acids

Chemical Science, Год журнала: 2024, Номер 15(16), С. 5832 - 5868

Опубликована: Янв. 1, 2024

Organocatalytic asymmetric synthesis has evolved over the years and continues to attract interest of many researchers worldwide. Enantiopure noncanonical amino acids (ncAAs) are valuable building blocks in organic synthesis, medicinal chemistry, chemical biology. They employed elaboration peptides proteins with enhanced activities and/or improved properties compared their natural counterparts, as chiral catalysts, ligand design, for syntheses complex molecules, including products. The linkage ncAA enantioselective organocatalysis, subject this perspective, tries imitate biosynthetic process. Herein, we present contemporary earlier developments field organocatalytic activation simple feedstock materials, providing potential ncAAs diverse side chains, unique three-dimensional structures, a high degree functionality. These strategies, useful forging wide range C-C, C-H, C-N bonds combinations thereof, vary from classical name reactions, such Ugi, Strecker, Mannich most advanced concepts deracemisation, transamination, carbene N-H insertion. Concurrently, some interesting mechanistic studies/models, information on chirality transfer Finally, perspective highlights, through diversity (AAs) not selected by nature protein incorporation, generic modes activation, induction, reactivity commonly used, enamine, hydrogen bonding, Brønsted acids/bases, phase-transfer reflecting increasingly important role applied chemistry.

Язык: Английский

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Organic Synthesis Away from Equilibrium: Contrathermodynamic Transformations Enabled by Excited-State Electron Transfer

Accounts of Chemical Research, Год журнала: 2024, Номер 57(13), С. 1827 - 1838

Опубликована: Июнь 21, 2024

ConspectusChemists have long been inspired by biological photosynthesis, wherein a series of excited-state electron transfer (ET) events facilitate the conversion low energy starting materials such as H

Язык: Английский

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