Transition Metal-Free Direct Trifluoromethylation of 2,3-Dihydropyridin-4(1H)-ones at Room Temperature

Synthesis and applications of S-(trifluoromethyl)-2,8-bis(trifluoromethoxy)dibenzothiophenium triflate (Umemoto reagent IV)

A new, powerful, and easy-to-handle electrophilic trifluoromethylating agent, S-(trifluoromethyl)-2,8-bis(trifluoromethoxy)dibenzothiophenium triflate (Umemoto reagent IV), was developed. Due to the extraordinary electronic effect of trifluoromethoxy group, Umemoto reagent IV was easily synthesized by a one-pot method from readily available 3,3'-bis(trifluoromethoxy)biphenyl. It was shown that Umemoto reagent IV was more powerful than Umemoto reagent II and could trifluoromethylate many kinds of nucleophilic substrates more effectively. In addition, Umemoto reagent IV was successfully utilized for the preparation of trifluoromethyl nonaflate, a useful trifluoromethoxylating agent. The direct conversion of 2,8-bis(trifluoromethoxy)dibenzothiophene to Umemoto reagent IV with triflic anhydride was achieved, albeit in low yield.

Nickel-Catalyzed Coupling Reaction of α-Bromo-α-fluoroketones with Arylboronic Acids toward the Synthesis of α-Fluoroketones

A nickel-catalyzed coupling reaction of α-bromo-α-fluoroketones with arylboronic acids was reported, which provides an efficient pathway to access 2-fluoro-1,2-diarylethanones in high yields. We also disclosed the synthesis of the monofluorination agents α-bromo-α-fluoroketones by using a trifluoroacetate release protocol. Mechanistic investigation indicated that a monofluoroalkyl radical is involved in the catalytic circle. Moreover, an important medical intermediate of flindokalner was synthesized via a nickel-catalyzed coupling reaction of α-bromo-α-fluoro-2-indolone and boronic ester.

Recent advances in direct trifluoromethylation of olefinic C-H bonds

The aim of this review is to provide a comprehensive overview of the direct trifluoromethylation of olefinic C-H bonds with special attention on the mechanistic aspects of the reactions. The review is divided into two major sections. The first focuses exclusively on trifluoromethylation of terminal alkenes, while the second will cover trifluoromethylation of internal alkenes. Literature has been surveyed until the end of April 2019.

Late stage functionalization of heterocycles using hypervalent iodine(iii) reagents

Late stage functionalization (LSF) through direct X-H manipulations (X = C, N) enables synthetic chemists to accelerate the diversification of natural products, agrochemicals and pharmaceuticals allowing rapid access to novel bioactive molecules without resorting to arduous de novo synthesis. LSF does not only allow tapping of the hitherto unexplored chemical space but also renders the synthetic sequence more straightforward, atom economical and cost-effective. In this regard, the recent decade has witnessed the emergence of hypervalent iodine(iii) reagents as a powerful synthetic tool owing to their easy availability, mild reaction conditions, remarkable oxidizing properties and high functional group tolerance. Iodine(iii) reagents have tremendous applications in the regio- and chemo-selective late-stage functionalization of a diverse variety of heterocycles through an exciting range of transformations, such as oxidative amination, cross-dehydrogenative coupling (CDC), fluoroalkylation, azidation, halogenation and oxidation. The present review, classified according to the types of synthetic methods involved, encompasses all these recent developments in the field of transition-metal-free iodine(iii)-catalyzed/mediated direct functionalizations of heterocycles with representative examples and insightful mechanistic discussions.

Autocatalyzed three-component cyclization of polyfluoroalkyl-3-oxo esters, methyl ketones and alkyl amines: a novel approach to 3-alkylamino-5-hydroxy-5-polyfluoroalkylcyclohex-2-en-1-ones

A new one-pot reaction between polyfluoroalkylated 3-oxo esters, methyl ketones and primary or secondary alkyl amines is reported as an efficient approach to 3-alkylamino-5-hydroxy-5-polyfluoroalkylcyclohex-2-en-1-ones. The scope of three-component cyclization and its plausible mechanism are discussed. The described protocol makes it possible to vary the functional substituents in 2, 3 and 5 positions of carbocycles. Anhydrous conditions are necessary for the productive synthesis of aminocyclohexenones, whereas in the presence of water the competitive formation of alkyl ammonium salts of keto hydroxy carboxylates is observed. Dehydration of the aminocyclohexenones was effectively used for the synthesis of 3-alkylamino-5-trifluoromethylphenols, some of which exhibited moderate antifungal activities against eight pathogenic fungal strains.

PIDA-mediated α-C–H functionalization of enaminones: the synthesis of thiocyano enaminones and chromones in water

Herein, an efficient, metal-free process for the α-C–H thiocyanation of enaminones was developed using PhI(OAc)₂ as an oxidant at room temperature in an aqueous medium.

Nickel-catalyzed C–H bond trifluoromethylation of 8-aminoquinoline derivatives by acyl-directed functionalization

A Ni(TFA)₂-catalyzed ortho-trifluoromethylation of 8-aminoquinoline derivatives was developed by C–H bond acyl-directed functionalization.

Catalyst-free and visible light promoted trifluoromethylation and perfluoroalkylation of uracils and cytosines

Fluoroalkylated enaminones, such as trifluridine and 5-trifluoromethyluracil, have widespread applications in pharmaceuticals and agrochemicals. Although these kinds of pharmaceutical agent often bear CF3 and perfluoroalkyl motifs in the core structure, access to such analogues typically requires multi-step synthesis. Here, we report a mild, metal-free and operationally simple strategy for the direct perfluoroalkylation of uracils, cytosines and pyridinones through a visible-light induced pathway from perfluoroalkyl iodides. This photochemical transformation features synthetic simplicity, mild reaction conditions without any photoredox catalyst, and high functional group tolerance, providing a facile route for applications in medicinal chemistry.

Recent Trifluoromethylation Reactions. A Mini Review Paper

This review highlights recent improvement in trifluoromethylene functionalization processes with CF3 reagents, includes: Togni’s, Umemoto’s, CF3SO2Cl, CF3I, Yagupol’skii-Umemoto, TMSCF3, Langlois (CF3SO2Na) and clarifies the several designing to result the corresponding trifluoromethylated products. In this article, the selective trifluoromethylation reactions with Togni’s reagents and their analogs are detailed, which work transition metals or photoactivated Ru or Ir catalysts as single electron giver to yield CF3 radical intermediate species. This issue is to introduce a draft of diverse reports, presenting the modern reaction collect and mechanics produced during the past five years. This task is demanded by the key protocol connected with the trifluoromethylation reactions, designing to sustain researchers a straight forward understanding of such reactions and to award information for further implements.

Synthesis of Multifunctionalized 2,3-Dihydro-4-pyridones and 4-Pyridones via the Reaction of Carbamoylated Enaminones with Aldehydes

The novel and effective diastereoselective synthesis of multifunctionalized dihydropyridones, including CF₃-substituted derivatives, has been developed on the basis of the piperidine-promoted domino reaction of carbamoylated enaminones with aldehydes. The products have been prepared in 38-90% yields and can be easily isolated by crystallization. Tautomerism, epimerization, and atropisomerism of dihydropyridones have been studied. The use of the resulting dihydropyridones in the synthesis of 1,2,6-trisubstituted 4-pyridone-3-carboxamides has been demonstrated via oxidative aromatization initiated by iodine.

C(sp2)-H Trifluoromethylation of enamides using TMSCF3: access to trifluoromethylated isoindolinones, isoquinolinones, 2-pyridinones and other heterocycles

A method for the direct C(sp2)-H trifluoromethylation of enamides, including biologically relevant isoindolinones, isoquinolinones and 2-pyridinones using TMSCF3 under oxidative conditions is presented. The protocol is convenient, operationally simple and exhibits high tolerance across a multitude of relevant handles and functional groups.

A catalyst-free approach to 3-thiocyanato-4H-chromen-4-ones

A facile and efficient approach to 3-thiocyanato-4H-chromen-4-ones from enaminones and KSCN was realized at room temperature. In addition, one-pot synthesis of 3-thiocyanatochromenones from 2-hydroxylacetophenones was also developed.

Efficient generation of perfluoroalkyl radicals from sodium perfluoroalkanesulfinates and a hypervalent iodine(iii) reagent: mild, metal-free synthesis of perfluoroalkylated organic molecules

Introduction of perfluoroalkyl groups into various organic molecules was achieved from sodium perfluoroalkanesulfinates and a hypervalent iodine(iii) reagent.

Regioselective C5-alkylation and C5-methylcarbamate formation of 2,3-dihydro-4-pyridones and C3-alkylation and C3-methylcarbamate formation of 4-(pyrrolidin-1-yl)furan-2(5H)-one

Reactions of N-alkyl-2,3-dihydro-4-pyridones and 4-(pyrrolidin-1-yl)furan-2(5H)-one with aldehydes and triethylsilane in a one-flask procedure provided C5 and C3 alkylated derivatives, respectively. Mannich-type reactions with formaldehyde and carbamates in the presence of lithium perchlorate furnished C5/C3 methylcarbamates.

Guanidinium iodide-catalyzed oxidative α-nitroalkylation of β-ketoamides

Oxidative nitroalkylation of β-ketoamides and nitroalkanes, mediated by hypoiodide generated from tert-butyl hydrogen peroxide and a catalytic amount of guanidinium iodide, afforded the corresponding α-nitroalkyl-β-ketoamides in up to 97% yield.