Chiral Photocatalyst Structures in Asymmetric Photochemical Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 1654 - 1716

Опубликована: Окт. 4, 2021

Asymmetric catalysis is a major theme of research in contemporary synthetic organic chemistry. The discovery general strategies for highly enantioselective photochemical reactions, however, has been relatively recent development, and the variety photoreactions that can be conducted stereocontrolled manner consequently somewhat limited. photocatalysis complicated by short lifetimes high reactivities characteristic photogenerated reactive intermediates; design catalyst architectures provide effective enantiodifferentiating environments these intermediates while minimizing participation uncontrolled racemic background processes proven to key challenge progress this field. This review provides summary chiral structures have studied solution-phase asymmetric photochemistry, including sensitizers, inorganic chromophores, soluble macromolecules. While some photocatalysts are derived from privileged both ground-state transformations, others structural designs unique offer insight into logic required photocatalysis.

Язык: Английский

---

Energy transfer photocatalysis: exciting modes of reactivity

Chemical Society Reviews, Год журнала: 2024, Номер 53(3), С. 1068 - 1089

Опубликована: Янв. 1, 2024

Leveraging light energy to expose the ‘dark’ reactive states describes whole essence of triplet–triplet transfer. This offers an impressive opportunity conduct a multitude diverse reactions and access sought-after molecular motifs.

Язык: Английский

---

Enantioselective [2+2]-cycloadditions with triplet photoenzymes

Nature, Год журнала: 2022, Номер 611(7937), С. 715 - 720

Опубликована: Сен. 21, 2022

Язык: Английский

---

Asymmetric Photocatalysis Enabled by Chiral Organocatalysts

ChemCatChem, Год журнала: 2021, Номер 14(1)

Опубликована: Окт. 21, 2021

Abstract Visible‐light photocatalysis has advanced as a versatile tool in organic synthesis. However, attaining precise stereocontrol photocatalytic reactions been longstanding challenge due to undesired photochemical background and the involvement of highly reactive radicals or radical ion intermediates generated under conditions. To address this problem expand synthetic utility reactions, number innovative strategies, including mono‐ dual‐catalytic approaches, have recently emerged. Of these, exploiting chiral organocatalysis, such enamine catalysis, iminium‐ion Brønsted acid/base N ‐heterocyclic carbene induce chirality transfer widely explored. This Review aims provide current, comprehensive overview asymmetric enabled by organocatalysts published through June 2021. The substrate scope, advantages, limitations, proposed reaction mechanisms each are discussed. review should serve reference for development visible‐light‐induced promote improvement chemical reactivity stereoselectivity these reactions.

Язык: Английский

---

Visible Light‐Mediated Dearomative Hydrogen Atom Abstraction/ Cyclization Cascade of Indoles

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(18)

Опубликована: Фев. 25, 2022

Abstract The photochemical synthesis of yet unknown 2‐oxospiro[azetidine‐3,3′‐indolines] (17 examples, 80–95 % yield), 2,4‐dioxospiro[azetidine‐3,3′‐indolines] (eight 87–97 and 1‐oxo‐1,3‐dihydrospiro[indene‐2,3′‐indolines] 85–97 yield) is described. Starting from readily accessible 3‐substituted indoles, a dearomatization the indole core was accomplished upon irradiation at λ=420 nm in presence thioxanthen‐9‐one (10 mol%) as sensitizer. Based on mechanistic evidence (triplet energy determination, deuteration experiments, by‐product analysis) it proposed that reaction proceeds by transfer via 1,4‐ or 1,5‐diradical intermediate. latter intermediates are formed excited state hydrogen atom suitable alkyl groups within C3 substituent to C2 carbon atom. Subsequent ring closure with pronounced diastereoselectivity generate 4‐ 5‐membered spirocyclic dearomatized product several options for further functionalization.

Язык: Английский

---

Controllable multiple-step configuration transformations in a thermal/photoinduced reaction

Nature Communications, Год журнала: 2022, Номер 13(1)

Опубликована: Май 23, 2022

Solid-state photochemical reactions of olefinic compounds have been demonstrated to represent powerful access organic cyclic molecules with specific configurations. However, the precise control stereochemistry in these remains challenging owing complex and fleeting configuration transformations. Herein, we report a unique approach regiospecific configurations C = groups intermediates by varying temperatures multiple-step thermal/photoinduced reactions, thus successfully realizing reversible ring closing/opening changes using single-crystal coordination polymer platform. All stereochemical transitions are observed situ X-ray diffraction, powder diffraction infrared spectroscopy. Density functional theory calculations allow us rationalize mechanism synergistic This can be generalized analysis possible transformations unravel detailed for any inorganic, macromolecular susceptible incorporation into platforms.

Язык: Английский

---

syn-Selective Difunctionalization of Bicyclobutanes Enabled by Photoredox-Mediated C–S σ-Bond Scission

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(43), С. 23771 - 23780

Опубликована: Окт. 18, 2023

Given the importance of cyclic frameworks in molecular scaffolds and drug discovery, it is intriguing to precisely forge manipulate ring systems synthetic chemistry. In this field, intermolecular synthesis densely substituted cyclobutanes with precise diastereocontrol under simple reaction conditions remains a challenge. Herein, photoredox strategy for difunctionalization bicyclo[1.1.0]butanes (BCBs) high regio- syn-selectivity disclosed. C-S σ-bond cleavage partially unsaturated sulfur-containing bifunctional reagents an overall strain-release-driven process enables thio-alkynylation, -alkenylation, -allylation BCBs mild demonstrates generality protocol. Mechanistic studies suggest that intermediacy distonic radical cations might be key efficient scission σ-bonds origin diastereoselectivity.

Язык: Английский

---

An update on chiral phosphoric acid organocatalyzed stereoselective reactions

Organic & Biomolecular Chemistry, Год журнала: 2023, Номер 21(17), С. 3477 - 3502

Опубликована: Янв. 1, 2023

This review article presents an in-depth analysis of the strategies and methodologies for using chiral phosphoric acids as organocatalysts in asymmetric syntheses from recent literature.

Язык: Английский

---

Highly Enantioselective Radical Cation [2 + 2] and [4 + 2] Cycloadditions by Chiral Iron(III) Photoredox Catalysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(28), С. 15054 - 15060

Опубликована: Июль 5, 2023

Radical cations show a unique reactivity that is fundamentally different from of conventional and have thus attracted considerable attention as alternative cationic intermediates for novel types organic reactions. However, asymmetric catalysis to promote enantioselective radical cation reactions remains major challenge in contemporary synthesis. Here, we report the judicious design an ion pair consisting chiral counteranion induces excellent level enantioselectivity. This strategy was applied enantio-, diastereo-, regioselective [2 + 2] cycloadditions, well [4 by using iron(III) photoredox catalysis. We anticipate this has potential expand use several mature anions develop numerous unprecedented

Язык: Английский

---

Enantioselective [2+2] Cross-Photocycloaddition Enabled by a Chiral Cage Reactor via Multilevel-Selectivity Control

ACS Catalysis, Год журнала: 2024, Номер 14(10), С. 7321 - 7331

Опубликована: Апрель 25, 2024

In the recently burgeoning field of asymmetric [2 + 2] photocycloaddition, a challenging hurdle lies in achieving multilevel control chemo-, regio-, diastereo-, and enantioselectivities cross-coupling photoreactions, which often result chaotic outcomes when partners show similar electronic optical properties. Here, we introduce biomimetic cage-pocket confined photocatalytic protocol that can effectively realize bimolecular recognition manipulate excited triplet-state dynamics through stereochemical confinement. This approach allows for highly selective synthesis heterocoupled syn-HH (head-to-head) enantiomers from two photoactive α,β-unsaturated carbonyl compounds, are typically difficult to access via conventional strategies due competitive pathways. We find cooperative heteromolecular binding plays critical role initial chemoselective successive stereoselective photoreactions. Notably, open pockets cage reactor display tolerable guest–host match but products–host mismatch wide scope substrates, overcoming common limitations associated with enzyme-mimicking reactors such as guest specificity product inhibition against catalytic generality turnover.

Язык: Английский

---