Formate Salts: The Rediscovery of Their Radical Reaction under Light Irradiation Opens New Avenues in Organic Synthesis

Abstract Formates are abundantly available and inexpensive commodity chemical, widely used in laboratory and industrial organic synthesis. Formates are promising hydrogen carrier and green C1 source, and have also been a subject of research as SET reductants in recent years. Compared to the toxic and flammable gas carbon monoxide, which also serves as a C1 source, formates are easier to handle, store, and transport, and are more environmentally friendly. Therefore, in recent studies of radical reactions, formate is not only as an ideal source of green carbonyl, which is of great significance to synthesize carboxyl compounds with various structures, but also as a SET reductant for editing organic molecules either in scientific research or industrial production. The activation and conversion of formate, as a source of C1 or a SET reductant, is a very challenging and hot research field in organic synthesis.