FeCl3-Mediated Synthesis of 2-(Trifluoromethyl)quinazolin-4(3H)-ones from Isatins and Trifluoroacetimidoyl Chlorides

A Phosphine-Free Air-Stable Mn(II)-Catalyst for Sustainable Synthesis of Quinazolin-4(3H)-ones, Quinolines, and Quinoxalines in Water

The synthesis, characterization, and catalytic application of a new phosphine-free, well-defined, water-soluble, and air-stable Mn(II)-catalyst [Mn(L)(H2O)2Cl](Cl) ([1]Cl) featuring a 1,10-phenanthroline based tridentate pincer ligand, 2-(1H-pyrazol-1-yl)-1,10-phenanthroline (L), in dehydrogenative functionalization of alcohols to various N-heterocycles such as quinazolin-4(3H)-ones, quinolines, and quinoxalines are reported here. A wide array of multisubstituted quinazolin-4(3H)-ones were prepared in water under air following two pathways via the dehydrogenative coupling of alcohols with 2-aminobenzamides and 2-aminobenzonitriles, respectively. 2-Aminobenzyl alcohol and ketones bearing active methylene group were used as coupling partners for synthesizing quinoline derivatives, and various quinoxaline derivatives were prepared by coupling vicinal diols and 1,2-diamines. In all cases, the reaction proceeded smoothly using our Mn(II)-catalyst [1]Cl in water under air, affording the desired N-heterocycles in satisfactory yields starting from cheap and readily accessible precursors. Gram-scale synthesis of the compounds indicates the industrial relevance of our synthetic strategy. Control experiments were performed to understand and unveil the plausible reaction mechanism.

Copper-Catalyzed Consecutive Ullmann, Decarboxylation, Oxidation, and Dehydration Reaction for Synthesis of Pyrrolo or Pyrido[1,2-a]imidazo[1,2-c]quinazolines

A protocol for a copper-catalyzed intermolecular cross-coupling cascade between 2-(2-bromoaryl)-1H-benzo[d]imidazole analogues and proline or pipecolic acid has been developed. The developed protocol allows access to a variety of synthetically useful N-fused pyrrolo or pyrido[1,2-a]imidazo[1,2-c]quinazoline scaffolds with high efficiency and good functional group compatibility. Proline or pipecolic acid plays a dual role in the reaction: as ligand and reactants. A mechanistically consecutive approach for the Ullmann coupling, decarboxylation, oxidation, and dehydration reaction process was presented.

Radical selenylative cyclization of trifluoromethyl propargyl imines for the synthesis of trifluoromethyl- and seleno-azaspiro[4,5]-tetraenones and quinolines

A radical selenylative cyclization of trifluoromethyl propargyl imines with diselenides for the regiodivergent construction of diversely functionalized azaspiro[4,5]-tetraenones and quinolines has been developed, which enables dual incorporation of CF₃ and Se groups into heterocycles in a one-pot reaction. When using Oxone as a green oxidant, the reaction proceeds through oxidative dearomative ipso-annulation or intramolecular ortho-annulation exhibiting good regioselectivity. The synthetic utility of this method is demonstrated by a scale-up reaction and further modification of the obtained products.

Ruthenium-Catalyzed Hydroxyl-Directed peri-Selective C-H Activation and Annulation of 1-Naphthols with CF3-Imidoyl Sulfoxonium Ylides for the Synthesis of 2-(Trifluoromethyl)-2,3-dihydrobenzo[de]chromen-2-amines

A ruthenium-catalyzed peri-selective C-H activation and annulation of 1-naphthols with CF₃-substituted imidoyl sulfoxonium ylides that uses hydroxyl as a weakly coordinating directing group is disclosed. The strategy provides a facile and practical route to diverse trifluoromethyl-containing 2,3-dihydrobenzo[de]chromen-2-amines with high efficiency. Notable advantages of this protocol include readily available materials, excellent regioselectivity, good functional group compatibility, and scalability.

A Direct Method for Synthesis of Fluorinated Quinazolinones and Quinoxalines Using Fluorinated Acids without Metals or Additives

The trifluoromethyl group only exists in synthetic compounds. Owing to the unique bioactivities of this group, the trifluoromethylation of alkanes, arenes, unsaturated compounds like olefins, aldehydes­, and ketones, and heterocycles has been studied constantly in recent decades. Herein, a direct method using trifluoroacetic acid as a CF3 source for the synthesis of 2-(trifluoromethyl)quinazolin-4-ones and 4-(trifluoromethyl)pyrrolo/indolo[1,2-a]quinoxalines without any catalysts or additives is reported; a wide range of fluorinated compounds were obtained in 52%–94% yield.

Controllable access to trifluoromethyl-containing indoles and indolines: Palladium-catalyzed regioselective functionalization of unactivated alkenes with trifluoroacetimidoyl chlorides

The synthesis of diverse products from the same starting materials is always attractive in organic chemistry. Here, a palladium-catalyzed substrate-controlled regioselective functionalization of unactivated alkenes with trifluoroacetimidoyl chlorides has been developed, which provides a direct but controllable access to a variety of structurally diverse trifluoromethyl-containing indoles and indolines. In more detail, with respect to γ,δ-alkenes, 1,1-geminal difunctionalization of unactivated alkenes with trifluoroacetimidoyl chloride enables the [4 + 1] annulation to produce indoles; as for β,γ-alkenes, a [3 + 2] heteroannulation with the hydrolysis product of trifluoroacetimidoyl chloride through 1,2-vicinal difunctionalization of alkenes occurs to deliver indoline products. The structure of alkene substrates differentiates the regioselectivity of the reaction.

A palladium-catalyzed dual functionalization of unactivated alkenes with trifluoroacetimidoyl chlorides toward the synthesis of structurally diverse trifluoromethyl-containing indoles and indolines has been developed.

Synthesis of 1-Amino-2,2,2-trifluoroalkylphosphonates from Alkene-Tethered Trifluoroacetimidoyl Chlorides

The reaction of alkene-tethered trifluoroacetimidoyl chlorides with trialkyl phosphites furnishes 1-amino-2,2,2-trifluoroalkylphosphonates. The products were generated in moderate to good yields, and the scalability of this process was showcased. Partial hydrolysis of the phosphonate moiety was achieved. The cyclization is proposed to occur via formation of an imidoyl phosphonate intermediate that becomes susceptible to nucleophilic attack at nitrogen through the strong electron-withdrawing groups at the imidoyl carbon.

The cascade coupling/iodoaminocyclization reaction of trifluoroacetimidoyl chlorides and allylamines: metal-free access to 2-trifluoromethyl-imidazolines

A metal-free cascade coupling/iodoaminocyclization reaction for the rapid assembly of 2-trifluoromethyl-imidazolines has been disclosed. The transformation applies readily accessible trifluoroacetimidoyl chlorides, allylamines and N-iodosuccinimides as the starting substrates, achieving an efficient and straightforward pathway to construct diverse imidazoline derivatives. Excellent efficiency of the reaction is observed (higher than 90% isolated yield for half of the examples), and the obtained imidazoline products bearing a pendent iodomethyl group could be easily transformed into other synthetically valuable compounds.

Synthesis of 3H-1,2,4-Triazol-3-ones via NiCl2-Promoted Cascade Annulation of Hydrazonoyl Chlorides and Sodium Cyanate

A nickel-promoted cascade annulation reaction for the facile synthesis of 3H-1,2,4-triazol-3-ones from readily available hydrazonoyl chlorides and sodium cyanate has been developed. The transformation occurs through a cascade nickel-promoted intermolecular nucleophilic addition-elimination process, intramolecular nucleophilic addition, and a hydrogen-transfer sequence. The method has been successfully applied for the construction of the core skeleton of the angiotensin II antagonist.

Silver-Mediated [3 + 2] Cycloaddition of Azomethine Ylides with Trifluoroacetimidoyl Chlorides for the Synthesis of 5-(Trifluoromethyl)imidazoles

A silver-mediated [3 + 2] cycloaddition of azomethine ylides with trifluoroacetimidoyl chlorides for the rapid assembly of 5-(trifluoromethyl)imidazoles has been developed. Notable features of the reaction include readily accessible reagents, a broad substrate scope, and high efficiency. The protocol can be successfully applied to construct the analogue of the specific allosteric modulator of GABA_A receptors. The silver species could be recycled by a simple operation.

Palladium-Catalyzed Cascade Carbonylative Synthesis of 1,2,4-Triazol-3-ones from Hydrazonoyl Chlorides and NaN3

A palladium-catalyzed three-component carbonylative reaction for the synthesis of 3H-1,2,4-triazol-3-ones from hydrazonoyl chlorides and NaN₃ has been achieved. The reaction presumably proceeds through a cascade carbonylation, acyl azide formation, Curtius rearrangement, and intramolecular nucleophilic addition sequence. A wide variety of structurally diverse 3H-1,2,4-triazol-3-ones were constructed in moderate to excellent yields. Benzene-1,3,5-triyl triformate (TFBen) was applied as a solid and convenient CO surrogate.

Copper-mediated [3 + 2] cycloaddition of trifluoroacetimidoyl chlorides and N-isocyanoiminotriphenylphosphorane for the synthesis of 3-trifluoromethyl-1,2,4-triazoles

Herein, a facile and straightforward route to synthesize 3-trifluoromethyl-1,2,4-triazoles via copper-mediated [3 + 2] cycloaddition of trifluoroacetimidoyl chlorides and N-isocyanoiminotriphenylphosphorane (NIITP) has been described.

Recent advances in cyclization reactions of isatins or thioisatins via C–N or C–S bond cleavage

This review summarizes recent developments on cyclization reactions induced by the C–N or C–S bond cleavage of isatins or thioisatins in the last 5 years, which produce fused products instead of spiro compounds.

Metal-free oxidative cyclization of trifluoroacetimidohydrazides with methylhetarenes: a facile access to 3-hetaryl-5-trifluoromethyl-1,2,4-triazoles

A metal-free oxidative cyclization of trifluoroacetimidohydrazides with methylhetarenes for the efficient synthesis of 3-hetaryl-5-trifluoromethyl-1,2,4-triazoles has been developed.

Recent advances and prospects in the iron-catalyzed trifluoromethylation reactions

The development of effective methods to create a C–CF₃ bond has attracted great attention in organofluorine chemistry and also in homogeneous catalysis.

Switchable and efficient conversion of 2-amido-aryl oxazolines to quinazolin-4(3H)-ones and N-(2-chloroethyl)benzamides

Switchable chemoselective conversion of 2-amido-aryl oxazolines to quinazolin-4(3H)-ones or N-(2-chloroethyl)benzamides is achieved.

Synthesis of 5-trifluoromethyl-1,2,3-triazoles via base-mediated cascade annulation of diazo compounds with trifluoroacetimidoyl chlorides

A metal-, azide- and CF₃-reagent free approach for the synthesis of 5-trifluoromethyl-1,2,3-triazoles via base-mediated cascade annulation of diazo compounds with trifluoroacetimidoyl chlorides has been developed.

Palladium-catalyzed three-component carbonylative synthesis of 2-(trifluoromethyl)quinazolin-4(3H)-ones from trifluoroacetimidoyl chlorides and amines

An efficient and practical approach for the synthesis of 2-(trifluoromethyl)quinazolin-4(3H)-ones through palladium-catalyzed three-component carbonylative reaction has been developed.