Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2017 - 2291

Опубликована: Ноя. 23, 2021

We present here a review of the photochemical and electrochemical applications multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms which both an proton exchanged together, often concerted elementary step. As such, MS-PCET can function as non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from wide variety common functional groups. introduction practitioner’s guide reaction design, with emphasis on unique energetic selectivity features that characteristic this class. then chapters oxidative N–H, O–H, S–H, C–H homolysis methods, generation corresponding neutral species. Then, reductive PCET activations involving carbonyl, imine, other X═Y π-systems, heteroarenes, where ketyl, α-amino, heteroarene-derived radicals be generated. Finally, we asymmetric catalysis materials device applications. Within each chapter, subdivide by group undergoing homolysis, thereafter type transformation being promoted. Methods published prior end December 2020 presented.

Язык: Английский

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Enantioselective Radical Reactions Using Chiral Catalysts

Chemical Reviews, Год журнала: 2022, Номер 122(6), С. 5842 - 5976

Опубликована: Янв. 24, 2022

Benefiting from the impressive increase in fundamental knowledge, last 20 years have shown a continuous burst of new ideas and consequently plethora catalytic methods for enantioselective radical reactions. This review aims to provide complete survey progress achieved over this latter period. The first part focuses on use chiral organocatalysts, these include catalysts covalently linked substrate those that interact with by weaker interactions like hydrogen bonds. second is devoted transition-metal redox catalysis which organized according increasing atomic number first-row transition metals (Ti, Cr, Fe, Mn, Co, Ni, Cu). Bioinspired manganese- iron-mediated hydroxylations oxidations are also discussed. A specific section dedicated reactivity Ru, Rh, Ir complexes as Lewis acids special focus at metal. Absorption photons result different events such energy transfer, single-electron hydrogen-atom transfer facilitating formation radicals. Organocatalysis has been successfully combined photocatalysts, opened pathways enlarging precursors available. merger photocatalysis organo- or metalla-photocatalysis brought novelty allowed discovery large original transformations. enzyme-catalyzed reactions involving intermediates largely benefit visible-light irradiation included review. provides comprehensive inventory goal detailing reaction mechanisms involved transformations any nonspecialist could find their own creativity invent yet unknown applications.

Язык: Английский

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Titanium catalysis for the synthesis of fine chemicals – development and trends

Chemical Society Reviews, Год журнала: 2020, Номер 49(19), С. 6947 - 6994

Опубликована: Янв. 1, 2020

Atlas as a Titan(ium) is holding the earth-abundant chemistry world. Titanium second most abundant transition metal, key player in important industrial processes (e.g. polyethylene) and shows much promise for diverse applications future.

Язык: Английский

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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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Reductive Deoxygenative Functionalization of Alcohols by First‐Row Transition Metal Catalysis

Chinese Journal of Chemistry, Год журнала: 2023, Номер 41(13), С. 1637 - 1652

Опубликована: Янв. 23, 2023

Comprehensive Summary Alcohols are among the most accessible functionalities. Catalytic deoxygenative functionalization of alcohols is highly synthetically appealing. While significant progress has been made on reactions with nucleophiles, electrophilic coupling partners remain a real challenge. This manuscript highlights advance in this direction, which mainly achieved by first‐row transition metals. The low‐valent titanium catalyst shown unique reactivity to homolytically cleave C—OH bonds. formed carbon radicals could either undergo reduction give protonation products or couple fragments form C—C chemistry initially realized using stoichiometric amount reagents and later extended catalytic variants. Nickel features variety oxidation states ranging from Ni 0 IV , both two‐electron oxidative addition single‐electron process involved their activation an electrophile. These properties enable nickel catalyze reductive R–X electrophiles. reaction first reported allylic alcohols, then benzylic and, very recently non‐activated alcohols. Recent effort resulted many invaluable methodologies that improve efficiency for construction aliphatic use cobalt copper catalysts not only expands substrate scope these but also shows new selectivity issues.

Язык: Английский

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Synthesis of Azabicyclo[3.1.1]heptenes Enabled by Catalyst-Controlled Annulations of Bicyclo[1.1.0]butanes with Vinyl Azides

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(27), С. 18565 - 18575

Опубликована: Июнь 27, 2024

Bridged bicyclic scaffolds are emerging bioisosteres of planar aromatic rings under the concept "escape from flatland". However, adopting this into exploration pyridines remains elusive due to challenge incorporating a N atom such bridged structures. Herein, we report practical routes for divergent synthesis 2- and 3-azabicyclo[3.1.1]heptenes (aza-BCHepes) as potential readily accessible vinyl azides bicyclo[1.1.0]butanes (BCBs) via two distinct catalytic annulations. The reactivity tailored with BCBs is key achieving transformations. Ti

Язык: Английский

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Ti-Catalyzed Formal [2π + 2σ] Cycloadditions of Bicyclo[1.1.0]butanes with 2-Azadienes to Access Aminobicyclo[2.1.1]hexanes

Organic Letters, Год журнала: 2024, Номер 26(8), С. 1745 - 1750

Опубликована: Фев. 20, 2024

Saturated bicyclic amines are increasingly targeted to the pharmaceutical industry as sp3-rich bioisosteres of anilines. Numerous strategies have been established for preparation bridgehead aminobicyclics. However, methods assemble bridge-amino hydrocarbon skeleton, which serves a meta-substituted arene bioisostere, limited. Herein, general approach access 2-aminobicyclo[2.1.1]hexanes (aminoBCHs) by titanium-catalyzed formal [2π + 2σ] cycloaddition bicyclo[1.1.0]butanes and 2-azadienes was developed. Simple derivatization aminoBCHs leads various medicinally agrochemically important analogues.

Язык: Английский

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Challenges and Future Perspectives in Photocatalysis: Conclusions from an Interdisciplinary Workshop

JACS Au, Год журнала: 2024, Номер 4(8), С. 2746 - 2766

Опубликована: Авг. 8, 2024

Photocatalysis is a versatile and rapidly developing field with applications spanning artificial photosynthesis, photo-biocatalysis, photoredox catalysis in solution or supramolecular structures, utilization of abundant metals organocatalysts, sustainable synthesis, plastic degradation. In this Perspective, we summarize conclusions from an interdisciplinary workshop young principal investigators held at the Lorentz Center Leiden March 2023. We explore how diverse fields within photocatalysis can benefit one another. delve into intricate interplay between these subdisciplines, by highlighting unique challenges opportunities presented each multidisciplinary approach drive innovation lead to solutions for future. Advanced collaboration knowledge exchange across domains further enhance potential photocatalysis. Artificial photosynthesis has become promising technology solar fuel generation, instance, via water splitting CO

Язык: Английский

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Electroreductive Olefin–Ketone Coupling

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(50), С. 20979 - 20986

Опубликована: Дек. 1, 2020

A user-friendly approach is presented to sidestep the venerable Grignard addition unactivated ketones access tertiary alcohols by reversing polarity of disconnection. In this work a ketone instead acts as nucleophile when adding simple olefins accomplish same overall transformation. The scope coupling broad enabled using an electrochemical approach, and reaction scalable, chemoselective, requires no precaution exclude air or water. Multiple applications demonstrate simplifying nature on multistep synthesis, mechanistic studies point intuitive mechanism reminiscent other chemical reductants such SmI2 (which cannot reaction).

Язык: Английский

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Photocatalytic Generation of π‐Allyltitanium Complexes via Radical Intermediates

Angewandte Chemie International Edition, Год журнала: 2020, Номер 60(3), С. 1561 - 1566

Опубликована: Окт. 3, 2020

Abstract The addition of π‐allylmetal complexes to carbonyls is the most important route homoallylic alcohols. This study reports first photocatalytic generation π‐allyltitanium by a radical strategy. novel strategy enables three‐component allylation with 1,3‐butadiene, providing rapid access valuable alcohols (over 60 examples). exceptional regio‐ and diastereoselectivity provided dual photoredox/Ti catalysis comparable that Cr‐catalyzed Nozaki–Hiyama–Kishi reaction.

Язык: Английский

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