Redox-neutral carbon–heteroatom bond formation under photoredox catalysis

Self Cite

This review presents an outline of current advancements in the photochemical and electrochemical synthesis of oxazoles and isoxazoles. Oxazole and isoxazole are important building blocks for a variety of medicinally useful compounds. Therefore, the synthesis of these heterocycles via sustainable technologies is worth demanding. Photochemical and electrochemical are two among the few sustainable technologies. This review covers a brief discussion on reaction parameters like catalysts, substrates scope, reaction temperature, solvents, electrodes, electrolytes (in case of electrochemical process), light source (in case of photochemical process) for individual reaction. Detailed discussion on mechanistic insight for each reaction is also presented. Finally, summary, and future direction toward the development of effective electrochemical and photochemical methods for the reaction of oxazoles and isoxazoles is also presented.

Section: Introductionmentioning

confidence: 99%

Photochemical and Electrochemical Synthesis of Oxazoles and Isoxazoles: An Update

Ghosh,

Sherin,

Ghosh

et al. 2024

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“…[57] More recently, carbon-heteroatom bond formation reaction under photocatalytic condition have also been elaborated for the synthesis of both cyclic and acyclic systems in the form of racemic version. [58] However, our current review represents a panoramic view of important contributions to the photocatalytic synthesis of chiral heterocycles via asymmetric CÀ O, CÀ N, CÀ S, and tandem CÀ N/CÀ O, CÀ S/CÀ O bonds formation up to the end of the year of 2023. The photocatalytic asymmetric reactions described herein will provide protocols for chiral heterocycle synthesis and inspire researchers worldwide for the future development of innovative strategies toward visible-light-induced enantioselective reactions.…”

Section: Introductionmentioning

confidence: 99%

Photochemical Synthesis of Chiral Heterocycles via Asymmetric Carbon‐Heteroatom Bond Formation

Brijwashi Sharma,

Saha,

Mohan Guru

2024

Chiral heterocyclic compounds play a crucial role in the pharmaceutical science, materials science, and agrochemical industries. The critical step for synthesizing chiral heterocycles is the formation of asymmetric carbon‐heteroatom bonds, which can be achieved in a chiral environment under thermal or photochemical conditions. However, photochemical asymmetric transformation has become an area of immense growth in the past 15 years. In the drug discovery and development era, chiral photochemical transformations have drawn the attention of researchers to develop new synthetic strategies for chiral heterocycles via asymmetric carbon‐heteroatom bond formation. Chiral photochemistry in the pathway of asymmetric synthesis requires a chirality source which is transferred to the products. A catalytic chiral metal complexing agent or a chiral photosensitizer that generally follows a single electron transfer (SET) or oxidative and reductive quenching cycle has been widely exploited to achieve this goal. In this review, we have demonstrated the recent development of photochemical synthesis of chiral heterocycles via asymmetric carbon‐heteroatom bond formation by using a chiral metal catalyst, asymmetric organocatalyst, or dual catalytic system based on their plausible mechanism.

“…[6] Another possible alternative is photoredox catalysis, which suffers from similar limitations as late-row transition metal complexes are often mandatory as photocatalysts to carry out desired transformations efficiently. [7] The field of organic electrosynthesis has experienced a recent resurgence because of its atomeconomic and sustainable features. [8] Moreover, additional flexibility in regulating the reaction parameters (e.g applied potential or electricity) is capable of providing superior chemoselectivity through controlled redox transformations.…”

Section: Introductionmentioning

confidence: 99%

Metal‐Free Electrochemical [3+2] Cycloaddition between α‐Amino Carbonyls and Tosylmethyl Isocyanide en route to Substituted Imidazoles

Mallick,

Baidya,

De Sarkar

2023

The established strategy unveils a metal and mediator‐free electrochemical [3+2] cycloaddition approach among α‐amino carbonyls and tosylmethyl isocyanide (TosMIC) fabricating substituted imidazole scaffolds. Implementation of electro‐redox conditions on this cycloaddition approach eliminates the essential requirement of transition metal catalysts and chemical oxidants. A wide variety of different functionalities are well tolerated under this reaction condition, contributing to the substrate scope and applicability. Several control experiments and cyclic voltammetry studies suggest an electro‐oxidation triggered successive C−C and C−N bond formations followed by rapid aromatization for constructing the five‐membered core structure.