Introduction of flavin anions into photoredox catalysis: acid-base equilibria of lumichrome allow photoreductions with an anion of an elusive 10-unsubstituted isoalloxazine

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F25%3A00635818" target="_blank" >RIV/61388955:_____/25:00635818 - isvavai.cz</a>

Alternative codes found

RIV/60461373:22310/25:43932041 RIV/60461373:22810/25:43932041

Result on the web

<a href="https://hdl.handle.net/11104/0366841" target="_blank" >https://hdl.handle.net/11104/0366841</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1039/d5sc01630d" target="_blank" >10.1039/d5sc01630d</a>

Result language

angličtina

Original language name

Introduction of flavin anions into photoredox catalysis: acid-base equilibria of lumichrome allow photoreductions with an anion of an elusive 10-unsubstituted isoalloxazine

Original language description

Flavins have been established as effective catalysts in oxidative photoredox catalysis. Conversely, their use in reductive photocatalysis remains limited, mainly due to the relatively low stability of the transient flavin radicals (semiquinones), which are used in photoreductions. The fully reduced forms of flavins are also disadvantaged in photocatalysis because they absorb light in the UV rather than in the visible region. In this work, we present a new approach for reductive flavin photocatalysis that utilises a flavin (isoalloxazine) anion derived from the elusive 10-unsubstituted 3,7,8-trimethylisoalloxazine, an unstable tautomer of 3-methyllumichrome. We found the conditions under which this isoalloxazine anion is formed by in situ deprotonation/isomerisation from the readily available 3-methyllumichrome and we subsequently used it as a photoredox catalyst in the reductive dehalogenation of activated bromoarenes and their C-P coupling reaction with trimethyl phosphite to form an arylphosphonate. Steady-state and transient absorption spectroscopy, NMR and cyclic voltammetry investigations, together with quantum chemical calculations, showed that the anion of oxidised isoalloxazine has several advantages, compared to other forms of flavins used in photoreductions, such as high stability, even in the presence of oxygen, an absorption maximum in the visible region, thereby allowing the use of excitation light between 470 and 505 nm, and a relatively long-lived singlet excited-state.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10405 - Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)

Project

<a href="/en/project/GF24-11386K" target="_blank" >GF24-11386K: Photoredox catalysis with organic anions – perspective area for flavin derivatives</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Chemical Science

ISSN

2041-6520

e-ISSN

2041-6539

Volume of the periodical

16

Issue of the periodical within the volume

25

Country of publishing house

GB - UNITED KINGDOM

Number of pages

9

Pages from-to

11255-11263

UT code for WoS article

001491832200001

EID of the result in the Scopus database

2-s2.0-105005807935