Metal-free trifluoroethylation of activated alkenes: rapid access to construct fluorinated 3,3-disubstituted 2-oxindoles

Visible-light-promoted difluoroamidated oxindole synthesis via electron donor-acceptor complexes

A method involving a metal-free visible-light-promoted synthesis was developed for the construction of difluoroalkylated oxindoles with N-phenylacrylamides and bromodifluoroacetamides as starting materials in the presence of N,N,N',N'-tetramethylethylenediamine (TMEDA). Twenty-four examples of the photochemical reaction were successfully performed, with good yields (44-99%) and excellent substrate adaptability. Mechanistic studies showed that the visible-light-promoted reaction involved a radical addition to N-phenylacrylamide, intramolecular cyclization, dehydrogenation, and rearomatization. The difluoroacetamide radical was produced as a result of electron transfer to bromodifluoroacetamides from the electron donor TMEDA in their electron-donor-acceptor (EDA) complexes under visible light irradiation. This protocol is a promising photochemical method due to its advantages of mild conditions, simple operation, wide substrate scope and high yields. And the obtained products may have great potential in the field of medicine.

Development of Electrophilic Radical Perfluoroalkylation of Electron-Deficient Olefins

Fluorinated organic compounds have attracted significant attention over the past few decades owing to their unique properties and versatility. An established method for the synthesis of fluorinated organic compounds involves radical perfluoroalkylation reactions towards double bonds. In this radical pathway, electrophilic perfluoroalkyl radicals exhibit excellent reactivity towards electron-rich olefins. Therefore, several splendid perfluoroalkylation reactions of electron-rich olefins have been reported. However, there are only a few examples of reaction involving electron-deficient olefins because of their poor electronic compatibility with perfluoroalkyl radicals. This review focuses on the reports that challenge this long-standing issue. Radical perfluoroalkylation/bifunctionalization reactions of electron-deficient olefins are described according to the radical generation methods.

Recent progress in aryltrifluoromethylation reactions of carbon-carbon multiple bonds

Due to the increasing relevance of fluorine-containing organic molecules in drug design, the synthesis of organofluorine compounds has gained high significance in synthetic organic chemistry. Trifluoromethylative difunctionalizations of carbon-carbon multiple bonds, with the simultaneous incorporation of a CF 3 group and another functional element, have considerable potential. Because of the high importance of carbon-carbon bond-forming reactions in organic synthesis, carbotrifluoromethylations and, in particular, aryltrifluoromethylations or heteroaryltrifluoromethylations are considered to be increasing fields of synthetic organic chemistry. The aim of the current review is to summarize recent developments of aryltrifluoromethylation or heteroaryltrifluoromethylation reactions.

Nickel-catalysed radical tandem cyclisation/arylation: practical synthesis of 4-benzyl-3,3-difluoro-γ-lactams

Enabled by nickel catalysis, a practical access to the synthesis of 4-benzyl-3,3-difluoro-γ-lactams has been developed via radical tandem cyclisation/arylation. This method features a nickel catalyst, high reaction efficiency, and good substrate tolerance and scope. This protocol proceeds through an intramolecular radical addition to form a primary alkyl radical followed by intermolecular Suzuki-type coupling.

Transition metal-free synthesis of fluoroalkylated oxindoles via base-mediated fluoroalkylation of N-arylacrylamides with RFI

A novel method for synthesizing fluoroalkylated oxindoles by the cyclization of N-arylacrylamides with fluoroalkyl iodide initiated with K₂CO₃ is reported.

Pd-catalyzed divergent trifluoroethylation and arylation of arylboronic acids by aryl(2,2,2-trifluoroethyl)iodonium triflates

Highly electrophilic aryl(2,2,2-trifluoroethyl)iodonium triflates have been used for the first time as trifluoroethyl and aryl transfer reagents in Pd-catalyzed functionalization of arylboronic acids. Electron-rich arylboronic acids reacted with aryl(2,2,2-trifluoroethyl)iodonium triflates (2a-b) in CH3CN in the presence of Pd2(dba)3 and K3PO4 at room temperature to provide trifluoroethyl arenes in up to 82% yield, while the reactions of both electron-rich and -poor arylboronic acids with 2a-b in DMF in the presence of Pd[P(t-Bu)3]2 and Cs2CO3 at 40 °C afforded arylation products in up to 99% yield. This tunable protocol allows access to trifluoroethyl arenes or biaryls in good to excellent yields under mild conditions and without the addition of extra ligands.

Transition metal free decarboxylative fluoroalkylation of N-acrylamides with 3,3,3-trifluoro-2,2-dimethylpropanoic acid (TFDMPA)

1,1-Dimethyl-2,2,2-trifluoroethyl substituted oxindoles were prepared by a novel transition metal-free decarboxylative fluoroalkylation of activated alkenes and C–H functionalization cascade process.