Radical Reactions for the Synthesis of 3‐Substituted Chroman‐4‐ones

Abstract

Radical cascade cyclizations of o‐allyloxybenzaldehydes have emerged as a powerful strategy for the synthesis of 3‐substituted chroman‐4‐ones. This minireview summarizes the incorporation of various functional groups into the C3‐position of chroman‐4‐ones by employing appropriate radical precursors through transition‐metal‐free systems, silver‐catalyzed systems, or visible‐light‐promoted systems.

Promising reagents for difluoroalkylation

“…48 Chroman-4-ones are an important motif in medicinal compounds and biologically active molecules. [49][50][51] In 2019, the Zhou group described a visible-light photoredox-catalyzed radical cascade cyclization of alkenyl aldehydes with BrCF 2 COR for the synthesis of various difluoroacetylated chroman-4-ones (Scheme 8). 52 Difluoroacetic acids were also found to be good difluoroalkyl radical precursors for decarboxylative difluoroalkylation.…”

Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K2S2O8

“…The chroman-4-one framework is a privileged structural motif found in numerous natural products and pharmaceuticals with extraordinary biological and pharmaceutical activities such as anticancer activities and anti-HIV activity among others ( Fig. 1 ) [ 1 – 3 ]. Therefore, the preparation of functionalized chroman-4-one derivatives has attracted great attention of experts and scientists in the field of organic synthesis and pharmaceutical sciences over the last few years [ 1 , 4 – 5 ].…”

“…1 ) [ 1 – 3 ]. Therefore, the preparation of functionalized chroman-4-one derivatives has attracted great attention of experts and scientists in the field of organic synthesis and pharmaceutical sciences over the last few years [ 1 , 4 – 5 ]. In general, chroman-4-one derivatives could be obtained via a polarity reversal strategy enabled by the N-heterocyclic carbene (NHC)-catalyzed intramolecular Stetter reaction [ 6 – 8 ].…”

Metal-free synthesis of phosphinoylchroman-4-ones via phosphinoylation/cyclization cascade mediated by K2S2O8

“…The chroman-4-one scaffolds are important structural motifs owing to their presence in many natural products and pharmaceuticals with extraordinary biological and pharmaceutical activities ( Figure 1) [1][2][3]. For instance, Liriopein B and Silibinin have shown significant anti-cancer activities and some chroman-4-one-containing compounds even have anti-HIV activity (Figure 1).…”

“…For instance, Liriopein B and Silibinin have shown significant anti-cancer activities and some chroman-4-one-containing compounds even have anti-HIV activity (Figure 1). Therefore, the preparation of functionalized chroman-4-ones and their related derivatives have received considerable attention over the last few years [1,4,5]. In general, the synthesis of chroman-4-ones can be achieved via a polarity reversal strategy enabled by the Nheterocyclic carbine (NHC) catalyzed intramolecular Stetter reaction [6][7][8].…”