Expedient chemoselective and catalyst-free synthesis of 3,3-difluorochroman-4-ones from o-hydroxyarylenaminones and Selectfluor

Highly Diastereoselective [3 + 2] Cycloaddition of Aziridines with Difluorinated Silyl Enol Ethers: Divergent Synthesis of 4,4-Difluoropyrrolidines and 4-Fluoropyrroles

A highly diastereoselective [3 + 2] cycloaddition of aziridines with difluorinated silyl enol ethers has been developed. This approach provides a facile methodology for highly functionalized gem-difluorinated pyrrolidines in good to excellent yields with good functional group tolerance. A one-pot, two-step approach for synthesis of structurally interesting fluorinated pyrroles has also been developed through a cycloaddition/aromatization/desulfonation sequence. Moreover, readily available substrates, mild reaction conditions, and easy scale-up synthesis show practical advantages.

Rhodium-Catalyzed Intramolecular Cyclization to Synthesize 2-Aminobenzofurans via Carbene Metathesis Reactions

Herein, we report a new method of synthesizing of 2-aminobenzofuran 3-enes via the formal C-S insertion reaction of alkyne-tethered diazo compounds. Metal carbene, as a kind of active synthetic intermediate, plays a very important role in organic synthesis. Through the carbene/alkyne metathesis strategy, a new donor carbene is produced in situ as a key intermediate, which has different reactions from the donor receptor carbene.

A Straightforward Approach to Fluorinated Pyrimido[1,2-b]indazole Derivatives via Metal/Additive-Free Annulation with Enaminones, 3-Aminoindazoles, and Selectfluor

A novel and efficient three-component reaction with two C-N bonds and one C-F bond formation has been reported, which provides a straightforward route to a variety of fluorinated pyrimido[1,2-b]indazole derivatives. This transformation has the advantage of excellent functional group compatibility, including aliphatic and aromatic substituents enaminones. Moreover, metal and additives are not necessary for this reaction, which is of great significance for the synthesis and application of fluorinated heterocycles.

Selective electrophilic di- and mono-fluorinations for the synthesis of 4-difluoromethyl and 4-fluoromethyl quinazolin(thi)ones by Selectfluor-triggered multi-component reaction

A simple and efficient domino protocol for the selective synthesis of 4-difluoromethyl and 4-fluoromethyl quinazolin(thi)ones was established from readily available 2-aminoacetophenones and iso(thio)cyanates mediated by Selectfluor. The reaction outcomes are...

Solvent-Dependent Cyclization of 2-Alkynylanilines and ClCF2COONa for the Divergent Assembly of N-(Quinolin-2-yl)amides and Quinolin-2(1H)-ones

Herein, we present an expedient Cu-catalyzed [5 + 1] cyclization of 2-alkynylanilines and ClCF₂COONa to divergent construction of N-(quinolin-2-yl)amides and quinolin-2(1H)-ones by regulating the reaction solvents. Notably, nitrile acts as a solvent and performs the Ritter reactions. ClCF₂COONa is used as a C1 synthon in this transformation, which also represents the first example for utilization of ClCF₂COONa as an efficient desiliconization reagent. The current protocol involves in situ generation of isocyanide, copper-activated alkyne, Ritter reaction and protonation.

Recent progress on selective deconstructive modes of halodifluoromethyl and trifluoromethyl-containing reagents

Halodifluoromethyl and trifluoromethyl-containing compounds are widely employed in organic chemistry, pharmaceuticals and materials science. Therefore, their applications and transformations have received significant attention during the past few decades. The single, double, triple and quadruple cleavage of halodifluoromethyl compounds and various deconstructive modes of trifluoromethyl-containing compounds could generate a variety of synthons to prepare more valuable products. Herein, we summarize the most significant achievements in this field with an intriguing focus on results from the last decade.

Selectfluor-triggered fluorination/cyclization of o-hydroxyarylenaminones: A facile access to 3-fluoro-chromones

A fast and efficient Selectfluor-triggered fluorination/cyclization reaction of o-hydroxyarylenaminones has been successfully developed. The reaction successfully provides an expedient method for the synthesis of 3-fluoro-chromones promoted by potassium carbonate, which shows readily available starting materials and is easy to operate. In addition, a plausible mechanism of this tandem cyclization reaction was proposed where 4 H-chromen-4-one, 2-(dimethylamino)-3,3-difluorochroman-4-one, and 3,3-difluoro-2-hydroxychroman-4-one were not found to be the reactive intermediates. Moreover, these novel compounds have been obtained in moderate to good yields, and their structures have been confirmed by 1H NMR, 13C NMR, and high-resolution mass spectrometry.

tert-Butyl Nitrite Mediated Synthesis of Fluorinated O-Alkyloxime Ether Derivatives

A tert-butyl nitrite (TBN)-mediated synthesis of fluorinated O-alkyloxime ether derivatives with bromodifluoroalkyl reagents as the fluorine sources has been developed. A variety of halodifluorinated compounds were found compatible, delivering the desired products in moderate to excellent yields. This transformation features a simple operation, can be done in air, and found to involve radicals. This protocol represents a straightforward approach to access various fluorinated O-alkyloxime ether derivatives.

S8-Catalyzed triple cleavage of bromodifluoro compounds for the assembly of N-containing heterocycles

An unprecedented S₈-catalyzed selective triple-cleavage of bromodifluoroacetamides is disclosed for the first time.

An unprecedented S₈-catalyzed selective triple-cleavage of bromodifluoroacetamides is disclosed for the first time. Valuable 2-amido substituted benzimidazoles, benzoxazoles and benzothiazoles were obtained in good to excellent yields in a cascade protocol in this strategy. Mechanistic studies suggested that a C2 source was generated in situ by selective cleavage of three C–X bonds, including two inert C(sp³)–F bonds on bromodifluoroacetamides, while leaving C–C bonds intact. This strategy will undoubtedly further consummate the role of halo difluoro compounds and enrich both fluorine chemistry and pharmaceutical sciences.

Transition metal-free assembly of 1,3,5-triazines using ethyl bromodifluoroacetate as C1 source

Transition-metal and oxidant-free annulation of amidine to access 2,4-disubstituted-1,3,5-triazines using ethyl bromodifluoroacetate as C1 source via quadruple cleavage.