Synthesis of 1,2-Disubstituted C-Aryl Glycosides via Palladium/Norbornene Cooperative Catalysis.

The Catellani reaction offers an opportunity to address multiple chemical bonds in a single pot. However, it is still quite a challenge to construct fully substituted olefins via this strategy, especially in electron-rich, unstable, and highly functionalized glycals. Herein we report the first palladium-catalyzed Catellani reaction for the direct preparation of 1,2-disubstituted C-aryl glycosides from easily available 2-iodoglycals, bromoaryl, and alkene/alkyne substrates. This transformation exhibits a wide substrate scope, accommodating diverse functional groups and intricate molecular frameworks. This innovative reactivity offers an efficient pathway to valuable 1,2-disubstituted carbohydrate analogues and molecular building blocks, facilitating novel strategic bond disconnections and broadening the reactivity landscape of palladium catalysis.

Highly Diastereoselective Synthesis of C-Glycosides from Glycal Anomers.

This Letter presents a highly diastereoselective synthesis of C-hydroxymethine glycosides from glycal anomers using a chiral N-heterocyclic carbene-copper catalyst. The high diastereoselectivity was synergistically controlled by the stereocenter of the substrate and chirality of the N-heterocyclic carbene-copper complex without being interrupted by the stereochemistry of C5 and the anomeric position. This approach enables the production of a diverse array of C-hydroxymethine glycosides using synthetically versatile glycals and various functionalized aldehydes.

Photoinduced Trifluoromethylation with CF3Br as a Trifluoromethyl Source: Synthesis of α-CF3-Substituted Ketones.

An efficient and novel photoinduced trifluoromethylation employing CF3Br as a trifluoromethyl source is described. With commercially accessible fac-Ir(III)(ppy)3 as the catalyst, radical trifluoromethylation between O-silyl enol ether and CF3Br occurs successfully. This method provides various α-CF3-substituted ketones with a broad substrate scope in good yields under mild reaction conditions.

Synthesis of 3-Trifluoromethyl-1,2,4-triazolines and 1,2,4-Triazoles via Tandem Addition/Cyclization of Trifluoromethyl N-Acylhydrazones with Cyanamide.

A tandem addition/cyclization reaction between trifluoromethyl N-acylhydrazones and cyanamide is described, which provides a novel and efficient process for the synthesis of polysubstituted 3-trifluoromethyl-1,2,4-triazolines and their derivatives. The method has the advantages of mild reaction conditions, a broad substrate scope, good product yields, and atom economy.

Visible-light promoted α-alkylation of glycine derivatives with alkyl boronic acids.

A visible-light-mediated aerobic α-alkylation reaction of glycine derivatives with alkyl boronic acids has been established in the presence of a Ru/Cu catalyst system, giving the desired radical coupling products efficiently. The transformation features mild reaction conditions and broad substrate scope, delivering a wide range of complex unnatural α-amino-acid derivatives.

Synthesis of CF3-Substituted 1,6-Dihydropyridazines by Copper-Promoted Cascade Oxidation/Cyclization of Trifluoromethylated Homoallylic N-Acylhydrazines.

A highly efficient strategy for the construction of CF3-substituted 1,6-dihydropyridazines has been developed by cascade oxidation/cyclization of trifluoromethylated N-acylhydrazines. The produced 1,6-dihydropyridazines could be easily transformed to 3-trifluoromethyl pyridazine derivatives. Some of the 1,6-dihydropyridazines exhibited aggregation-induced emission (AIE). DFT calculations were conducted to explain the mechanism.

Diastereoselective synthesis of spiro-cyclopropanyl-cyclohexadienones via direct sulfide-catalyzed [2 + 1] annulation of para-quinone methides with bromides.

An efficient sulfide-catalyzed [2 + 1] annulation of para-quinone methides (p-QMs) with diverse bromides has been achieved. This catalytic strategy provides an efficient and straightforward protocol for accessing a variety of spiro-cyclopropanyl-cyclohexadienone compounds in good to excellent yields (64% to 96% yields) with outstanding diastereoselectivities (>20 : 1 dr), displaying good functional group tolerance as well as gram-scale capacity.

Visible-light-promoted acyl radical cascade reaction for accessing acylated isoquinoline-1,3(2H,4H)-dione derivatives.

A visible-light-promoted decarboxylative acyl radical acylation/cyclization cascade reaction of N-methacryloylbenzamides for accessing acylated isoquinoline-1,3(2H,4H)-dione derivatives was described. In this report, α-keto acids were used for generating acyl radicals and inducing radical acylations. This protocol features mild reaction conditions, operational practicality and a broad substrate scope.

Synthesis of Polysubstituted Trifluoromethylpyridines from Trifluoromethyl-α,ß-ynones.

A novel and efficient method for synthesis of polysubstituted trifluoromethylpyridine derivatives by the Bohlmann-Rahtz heteroannulation reaction is described, which use trifluoromethyl-α,ß-ynones as trifluoromethyl building blocks to react with ß-enamino esters or ß-enamino ketones in the presence of ZnBr2 to form the trifluoromethylpyridine derivatives in good yields. The protocol has the advantages of readily available starting materials, mild reaction conditions, and high atom economy.

Visible-light induced decarboxylative alkylation of quinoxalin-2(1H)-ones at the C3-position.

A simple and efficient method for the visible light induced direct carbon alkylation of quinoxalin-2(1H)-ones at the C3 position is described. This protocol employs cheap and readily available phenyliodine(iii) dicarboxylates as the alkylation reagents to conduct decarboxylative radical coupling reaction with quinoxalin-2(1H)-ones. The process exhibits excellent compatibility to functional groups and provides a convenient and selective access to various 3-alkylquinoxalin-2(1H)-ones in good yields.

Double-Oxidative Dehydrogenative [4+2]-Cyclization/Dehydrogenation/Oxygenation Tandem Reaction of N-Arylglycine Derivatives with Cumenes.

Double-oxidative dehydrogenative (DOD) cyclization is one of the most straightforward strategies for the synthesis of cyclic compounds. A novel approach to substituted 3,4-dihydroquinoline-3-one derivatives via a Cu(II)/DDQ/O2 system-catalyzed DOD [4+2]-cyclization/dehydrogenation/oxygenation cascade reaction of N-arylglycine derivatives, cumenes, and O2 has been developed.

Tin Powder-Promoted Cascade Condensation/Allylation/Lactamization: Synthesis of Isoindolinones and Pyrazoloisoindol-8-ones.

An efficient tin powder-promoted cascade condensation/allylation/lactamization of 2-formylbenzoic acids, hydrazides, and allyl bromides was developed for the synthesis of isoindolinones in good to excellent yields under mild conditions without any other additives or catalysts. Further manipulation of isoindolinones by iodocyclization process afforded the tricyclic tetrahydro-8 H-pyrazolo[5,1- a]isoindol-8-one derivatives, which could be converted into more complicated tetracyclic tetrahydro-4 H-azirino[1',2':2,3]pyrazolo[5,1- a]isoindol-4-ones.

[3 + 2] Cycloaddition of para-Quinone Methides with Nitrile Imines: Approach to Spiro-pyrazoline-cyclohexadienones.

[3 + 2] cycloaddition of para-quinone methides with nitrile imines under mild conditions has been achieved. The corresponding spiro-pyrazoline-cyclohexadienone products were constructed in good to excellent yields (up to 97% yield) with high regioselectivity. This straightforward protocol exhibits good functional group tolerance and scalability and provides the spiro-pyrazoline-cyclohexadienones.

N-Arylations of trifluoromethylated N-acylhydrazones with diaryliodonium salts as arylation reagents.

A novel and efficient N-arylation of trifluoromethylated N-acylhydrazones is described by using diaryliodonium salts as arylation reagents in the presence of copper salts. A wide variety of N-aryl acylhydrazones are obtained with good to excellent yields under mild reaction conditions.

Tandem radical cyclization of N-methacryloyl benzamides with CBr4 to construct brominated isoquinolinediones.

A simple cumene (isopropylbenzene, IPB) promoted auto-oxidation involved tandem radical cyclization of N-methacryloyl benzamides using stable and easy-to-handle CBr4 as the bromine source is described. This strategy provides an efficient and practical approach for the synthesis of bromine containing isoquinolinediones. This method also presents a new way to generate bromine radicals using a mild auto-oxidation pathway.

Double-Oxidative Dehydrogenative (DOD) [4 + 2]-Cyclization/Oxidative Aromatization Tandem Reaction of Glycine Derivatives with Ethylbenzenes.

The double-oxidative dehydrogenative (DOD) cyclization represents one of the most straightforward and atom-economical methods for cyclic structure formation. A Cu(II)/DDQ/O2 system-catalyzed DOD [4 + 2]-annulation/oxidative aromatization tandem reaction of readily available glycine derivatives and alkylbenzenes was established. This approach facilitates rapid access to a broad scope of substituted quinoline-2-carboxylate derivatives, an important motif in drug discovery. The reaction could feasibly be applied to a 10 gram-scale synthesis.

Synthesis of Trifluoroethyl Pyrazolines via Trichloroisocyanuric Acid Promoted Cascade Cyclization/Trifluoromethylation of ß,γ-Unsaturated Hydrazones.

A novel and efficient protocol for the construction of trifluoroethyl pyrazolines has been developed by cascade cyclization/trifluoromethylation reaction of ß,γ-unsaturated hydrazones. This strategy uses cheap and commercially available trichloroisocyanuric acid as promoter and TMSCF3 as the trifluoromethylating reagent, which make the trifluoromethylating process much cheaper. A wide range of substrates can be applied in this process to afford the trifluoroethyl pyrazolines in good yield.

Air promoted annulation of thiophenols with alkynes leading to benzothiophenes.

Air promoted intermolecular annulation of thiophenols with alkynes, leading to complex benzothiophenes, is reported. This atom-economical reaction is performed in the absence of any catalyst, chemical oxidant and additive. Only a solvent and an air atmosphere were required. A plausible radical involved mechanism is proposed.

Cascade Oxidation/Halogenoaminocyclization Reaction of Trifluoromethylated Homoallylic N-Acylhydrazines: Metal-free Synthesis of CF3-Substituted Pyrazolines.

An efficient and practical cascade oxidation/halogenoaminocyclization of trifluoromethylated homoallylic N-acylhydrazines is developed. The protocol enables an efficient access to various biologically interesting CF3-containing pyrazoline compounds from readily accessible trifluoromethylated homoallylic N-acylhydrazines in good to excellent yields under mild conditions without any other additives or catalysts. The produced pyrazoline compounds can be further manipulated to other more complicated derivatives through transformation of residual halogen atom.

Synthesis of trifluoromethylated pyrazolidines by [3 + 2] cycloaddition.

A highly efficient [3 + 2] cycloaddition between trifluoromethylated N-acylhydrazones and nitroolefins in the presence of potassium hydroxide under phase transfer catalysis is developed to afford potentially bioactive trifluoromethylated pyrazolidines, which can be further transformed into trifluoromethylated pyrazoles in good yields.