Applications of Benzothiazolines as Hydrogen Atom Donors and Functional Group Transfer Reagents in Organic Synthesis

Abstract In modern organic synthetic chemistry, considering technical, economic, and environmentally friendly aspects promote the search for novel reactions possessing atom and step economy, with non‐toxic chemical reagents and releasing ecofriendly byproducts that could efficiently construct C─C bonds and C─X (X ═ heteroatom) bonds. Thus, more specific, selective and effective reagents remain desirable. Benzothiazolines are important classes of heterocycles, displaying a wide range of biological and medicinal activities. They have been primarily used as hydrogen atom donors for various reductive processes under Brønsted acid or Lewis acid catalysis. In addition, their C2‐substituted derivatives are competent to serve as carbanion types of alkyl‐and acyl‐transfer reagents under thermal reaction conditions. Recently, photochemistry has arisen as a powerful synthetic tool granting access to radical intermediate simply with good functional group compatibility under mild conditions, and applications of benzothiazolines in radical chemistry have been explored until very recently. This review will discuss the methods for the synthesis of C2‐substituted benzothiazolines since 2018, and the applications of benzothiazolines as hydrogen atom donors and functional group transfer reagents with a particular attention on their transformations under thermal and photocatalysis conditions. We hope this review will draw inspiration to readers for further exploration of this field.