Synthesis of CF2H-containing isoquinoline-1,3-diones through metal-free, visible-light and air-promoted radical difluoromethylation/cyclization of N-benzamides

Recent Advances in Visible Light-Mediated Radical Fluoro-alkylation, -alkoxylation, -alkylthiolation, -alkylselenolation, and -alkylamination

In the last few years, many reagents and protocols have been developed to allow for the efficient fluorofunctionalization of a diverse set of scaffolds ranging from alkanes, alkenes, alkynes, and (hetero)arenes. The concomitant rise of organofluorine chemistry and visible light-mediated synthesis have synergistically expanded the fields and have mutually benefitted from developments in both fields. In this context, visible light driven formations of radicals containing fluorine have been a major focus for the discovery of new bioactive compounds. This review details the recent advances and progress made in visible light-mediated fluoroalkylation and heteroatom centered radical generation.

Visible-light photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamides with S-(difluoromethyl)sulfonium salt

A facile and highly efficient visible-light photoredox-catalyzed protocol for aryldifluoromethylation of acrylamides was developed using S-(difluoromethyl)sulfonium salt as the difluoromethyl source. With this method, pharmaceutically interesting CF₂H-containing oxindoles were readily accessed from N-arylacrylamides, and this method featured mild reaction conditions, a broad scope of substrates, good tolerance of functional groups, and good to excellent yields. Control experiments revealed that this protocol proceeded through a difluoromethylation/cyclization cascade process.

Visible-Light-Mediated Tandem Difluoromethylation/Cyclization of Alkenyl Aldehydes toward CF2H-Substituted Chroman-4-one Derivatives

An efficient and facile visible-light-mediated tandem difluoromethylation/cyclization of alkenyl aldehydes, with easily accessible and air-stable [Ph₃PCF₂H]⁺Br^- as the difluoromethylation reagent, has been established. A range of CF₂H-substituted chroman-4-one skeletons and their derivatives, such as 2,3-dihydroquinolin-4(1H)-ones, chroman, 3,4-dihydronaphthalen-1(2H)-one, 2,3-dihydrobenzofuran, and 2,3-dihydro-1H-inden-1-one, are efficiently produced in moderate to good yields with excellent chemoselectivity under mild reaction conditions.

Difluoromethylarylation of Alkynes from [Bis(difluoroacetoxy)iodo]benzene: Access to CF2H-Containing Dibenzazepines

A photoinduced radical difluoromethylarylation via tandem addition-cyclization of alkynes with easily available [bis(difluoroacetoxy)iodo]benzene is accomplished, providing a straightforward and practical route for the construction of difluoromethylated dibenzazepines. Various sensitive functional groups can be compatible under photoinduced conditions. Mechanism investigation reveals that this transformation is initiated by the addition of alkyne with difluoromethyl radical, generated in situ from [bis(difluoroacetoxy)iodo]benzene.

State of knowledge in photoredox-catalysed direct difluoromethylation

The combination of visible light photoredox catalysis with direct difluoromethylation has allowed the synthesis of a large choice of CF2H-containing value-added molecules under very mild reaction conditions.

Photoredox-catalyzed direct C(sp2)–H difluoromethylation of enamides or heterocycles with [bis(difluoroacetoxy)iodo]benzene

A photoredox-catalyzed direct C(sp2)–H difluoromethylation of enamides and heterocycles is accomplished by using easily accessible [bis(difluoroacetoxy)iodo]benzene as the CF2H source.