UV/Visible Light Promoted External Photocatalyst Free Transformations: One Decade Journey to N-Heterocycles and its Functionalisation

Abstract

Heterocycles continue to captivate the attention of scientists due to their distinctive structures, which have resulted in numerous practical uses across various fields including organic chemistry, pharmaceuticals, and materials science. They have been recognized as the fundamental framework of a variety of compounds that hold significance in both biological and industrial applications. In the realm of organic synthesis, the activation of small molecules through visible-light promoted reactions become more easier in the presence of photocatalyst but complex reaction conditions were required to achieve the target. Nowadays significant attention has been made by the researcher via the design of photoactive scaffolds which itself absorb light and participate for cyclization or functionalization. To study the whole finding under photocatalyst free activation in a single platform a review is necessary which will guide the new researchers to solve the critical problems. In this context we have provided a comprehensive analysis of the synthesis of N-containing heterocyclic compounds and their functionalization without the use of external photocatalysts, under visible-light exposure in different conditions, with a detailed description of various scopes, limitations and mechanistic investigation on research findings published since 2015.