Simple Operation Group Research Articles

Photoinduced Metal-Free Decarboxylative Fluoroalkylation of Alkenes for the Synthesis of N-Arylbutanamides and Oxindoles.

The visible light-induced decarboxylative cascade reaction of fluoroalkyl carboxylic acids has been achieved for the efficient synthesis of fluorinated compounds. However, most of the transformations rely on noble iridium metal complex. Herein, a visible light-induced metal-free decarboxylative cascade reaction of fluoroalkyl carboxylic acids has been realized. This protocol features simple operation, transition metal free, and good functional group tolerance.

EDA Complex-Enabled Annulation to Access CF2-Containing Tetralones and Quinazolinones Using Persulfates as Electron Donors.

A photocatalyst-free and EDA complex-enabled radical cascade cyclization reaction of inactive alkenes with bromodifluoroacetamides was reported for the divergent synthesis of fluorine-containing tetralones and quinazolinones. In this transformation, persulfates as electron donors and difluoro bromamide as electron acceptors generate the EDA complex. This is a promising photochemical method with advantages such as mild reaction conditions, simple operation, being metal-free, and excellent functional group tolerance.

Metal-Free Cyanation of gem-Difluoroalkenes via Azide-Mediated C-C Double Bond Fragmentation.

Activation and cleavage of C-C double bonds are long-standing challenges in synthetic chemistry. Herein, we report an unprecedented azide-mediated C-C double bond fragmentation of gem-difluoroalkenes under mild and metal-free conditions, enabling the efficient synthesis of structurally diverse aromatic nitriles in moderate to good yields. This protocol is also amenable to the cyanation of gem-dichloro and dibromo alkenes. This reaction features simple operation and good functional group compatibility and can be implemented at a gram scale.

One–pot synthesis of 1,2,4-triazole-Fused heterocycles via sequential condensation and iron-catalyzed aerobic oxidation

A one-pot method has been devised for the synthesis of 1,2,4-triazole-fused heterocycles. This method involves the condensation of commercially available (hetero)aromatic/aliphatic aldehydes and 2-hydrazinopyridine derivatives, succeeded by iron-catalyzed oxidation using O2 in air as the oxidant and without using any ligands or additives. The salient merits of this chemistry include broad substrate scope, simple operation, one-pot synthesis, and excellent functional group tolerance, as well as the use of air, a cheap and abundant iron catalyst, and ligand- and additive-free conditions. The efficacy of this synthetic method has been demonstrated through the synthesis of 30 examples of 1,2,4-triazole-fused heterocycles with diverse substituents in moderate to excellent yields. Furthermore, the successful synthesis of an antibacterial agent has been achieved with a satisfactory yield.

Synthesis of α-sulfenylated carbonyl compounds under metal-free conditions.

An efficient synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols under heating conditions is described. The method is characterized by mild conditions, simple operation, metal-free catalysis and good functional group tolerance. Mechanistic studies suggest that the reaction involves a radical pathway and an isomerization process.

Visible-light-induced photocatalyst-free cascade cyclization of 3-(2-(ethynyl)phenyl)quinazolinones to sulfonated quinolino[2,1-b]quinazolinones.

A visible-light-induced K2S2O8-promoted cascade sulfonation/cyclization reaction was established using 3-(2-(ethynyl)phenyl)quinazolinones as efficient substrates under mild conditions. A series of sulfonated quinolino[2,1-b]quinazolinones were successfully synthesized under transition-metal- and photocatalyst-free conditions. Notably, this strategy has the advantages of room temperature and simple operation, easy scale-up, and good functional group tolerance.

Copper-Catalyzed Fluoroalkylphosphorothiolation of Alkynes for the Synthesis of (E)-β-Fluoroalkyl Vinyl Phosphorothioates.

A convenient copper-catalyzed three-component radical-based fluoroalkylphosphorothiolation of terminal alkynes with (iPrO)2P(O)SH and fluoroalkylation reagent for the synthesis of a variety of (E)-β-fluoroalkyl vinyl phosphorothioates with excellent regioselectivity and stereoselectivity has been developed. All the starting materials used in this reaction are highly stable and readily available. Thus, this process features with mild reaction conditions, simple operation and good functional group tolerance (>40 examples). Furthermore, this modular reaction system allows the late-stage functionalization of bioactive molecules.

Construction of α-Halogenated Boronic Esters via Visible Light-Induced C-H Bromination.

α-Halogenated boronic esters are versatile building blocks that can be diversified into a wide variety of polyfunctionalized molecules. However, their synthetic potential has been hampered by limited preparation methods. Herein, we report a visible light-induced C-H bromination reaction of readily available benzyl boronic esters. This method features high yields, mild conditions, simple operation, and good functional group tolerance. The analogous chlorides and iodides can be accessed via Finkelstein reaction. Synthesis of halogenated geminal diborons has also been demonstrated.

Copper-Catalyzed Synthesis of S-S Bond-Containing Silanols from SCBs and Trisulfide-1,1-dioxides.

In this work, an efficient method for the copper-catalyzed ring-opening hydrolysis of silacyclobutanes to silanols was developed. This strategy has the advantages of friendly reaction conditions, simple operation, and good functional group compatibility. No additional additives are required in the reaction, and the S-S bond can also be introduced into the organosilanol compounds in one step. Furthermore, the success at the gram scale demonstrates the great potential of the developed protocol for practical industrial applications.

Switchable Regioselective 7-endo or 6-exo Iodocyclization of O-Homoallyl Benzimidates

We present a facile switchable regioselective 7-endo or 6-exo iodocyclization of O-homoallyl benzimidates here, which affords various iodo-substituted 1,3-oxazines and tetrahydro-1,3-oxazepines in a controllable manner. The products can further undergo substitution reactions to afford a series of rich functionalized target heterocyclic molecules. The developed protocol has the advantages of mild conditions, simple operation, and excellent functional group compatibility.

Hydrogen Bond Donor and Unbalanced Ion Pair Promoter-Assisted Gold-Catalyzed Carbon–Oxygen Cross-Coupling of (Hetero)aryl Iodides with Alcohols

We have developed an efficient gold-catalyzed C–O cross-coupling reaction of (hetero)aryl iodides with primary and secondary alcohols via an AuI–AuIII catalytic cycle. This protocol featured moisture/air insensitivity, simple operation, and excellent functional group tolerance. Good yields were obtained regardless of steric hindrance and electronic factor (electron-rich or poor) of substrates, and the chirality of chiral alcohol starting materials could be preserved. Our protocol worked well for both intermolecular and intramolecular couplings. In addition, the RuPhos ligand was applied to gold-catalyzed cross-couplings. An unbalanced ion pair promoter and hydrogen bond donor solvent might be crucial in this transformation.

Visible-Light-Promoted bis(Difluoromethylation)/Cyclization of 2-Vinyloxy Arylalkynes to Prepare Benzofuran Derivatives.

A visible-light-promoted difluoromethylation/cyclization of 2-vinyloxy arylalkynes was developed, providing a variety of bis(difluoromethyl)-substituted benzofurans in moderate to good yields. A plausible mechanism involving difluoromethyl radical cascade cyclization and solvent-promoted ionic addition was proposed. This protocol has the advantages of having mild reaction conditions, simple operation, and good functional group tolerance.

Transition-Metal-Free Domino Reaction of [60]Fullerene, Indole, and DMSO/HCl: One-Pot Access to Diverse N-Substituted [60]Fulleroindole Derivatives.

An unprecedented multicomponent domino reaction of [60]fullerene, indole, and DMSO/HCl has been developed for the one-pot efficient synthesis of diverse N-substituted [60]fulleroindole derivatives. This methodology features simple operation, low cost, and transition-metal-circumvented and good functional group tolerance in indole.

Synthesis of acridines via copper-catalyzed amination/annulation cascades between arylboronic acids and anthranils.

Copper-catalyzed tandem cyclization reactions between arylboronic acids and anthranils have been established, providing new approaches for one-pot assembly of azacycle acridines. This one-pot protocol features simple operation, precious-metal-free conditions and good functional group compatibility, thus providing an efficient approach for the synthesis of a variety of acridines in moderate to good yields.

The synthesis of anticancer sulfonated indolo[2,1-a]isoquinoline and benzimidazo[2,1-a]isoquinolin-6(5H)-ones derivatives via a free radical cascade pathway.

A facile CuBr2 induced radical relay addition/cyclization of activated alkenes with substituted-thiosulfonates has been achieved, leading to a broad range of sulfonated indolo[2,1-a]isoquinolines and benzimidazo[2,1-a]isoquinolin-6(5H)-ones in moderate to good yields. In particular, some compounds exhibit bioactivity against cancer cell lines. This protocol shows advantages of low-cost, base-free, simple operation, and broad functional group tolerance.

Regioselective synthesis of di-aromatic ring-fused 2,8-dioxa/dithia bicyclo[3,3,1]nonane derivatives via recyclable polymeric Brønsted acid-catalyzed one-pot tandem formation of multiple chemical C–C/C–O and C–C/C–S bonds

An environmentally benign and straightforward synthetic approach for the assembly of a new class of diverse symmetrical substituted di-aromatic-fused 2,8-dioxa/dithiabicyclo[3,3,1]nonane derivatives containing methylene-bridged bicyclic framework via reusable cross-linked polystyrene-supported p-toluenesulfonic acid-catalyzed tandem reactions of substituted phenols/selected thiophenol with 1,1,3,3-tetramethoxypropane under neat conditions has been reported in which four new chemical bonds (two C–C/two C–O)-(two C–C/two C–S), two new six-membered cycles, and two new stereogenic tertiary carbon centers were constructed in a single operation. The synthetic utility of this method was also demonstrated. In addition, this present protocol could be successfully extended to the selected naphthols and dihydroxynaphthalenes as the enol partner of phenols with high efficiency. The developed transformation featured high efficiency, the use of commercially accessible feedstocks, excellent regioselectivity, simple operation, gram-scale synthesis, and good functional group compatibility. Furthermore, the solvent-free conditions, easily recoverable catalyst, and efficient recycling render the protocol green, economic and sustainable.

Magnesium chloride (MgCl2) catalyzed highly regioselective C-3 ring opening of 2,3 epoxy alcohols by N-nucleophile

We herein report Magnesium chloride (MgCl2) catalyzed first highly C3-selective ring-opening reaction of various 2,3-epoxy alcohols with assorted N-Nucleophiles and sodium azide to furnish 3-amino-1,2 diols and 3-azido-1,2 diols respectively in high yields under mild reaction conditions. This protocol attributes the use of catalytic amount of Magnesium chloride (MgCl2), simple reaction conditions, practical operation and broad functional group tolerance.

Copper‐Catalyzed Decarboxylative Reductive Sulfonylation of α‐Oxocarboxylic Acids with Aryl Sulfonyl Hydrazines

AbstractA novel and facile synthesis of aryl benzyl sulfones was accomplished for the first time through copper‐catalyzed decarboxylative reductive sulfonylation reaction between α‐oxocarboxylic acids and aryl sulfonyl hydrazines. The protocol proceeds smoothly under simple conditions, and has the advantages of simple operation, high yields and good functional group compatibility. This approach realizes a conceptually novel methodology for aryl benzyl sulfone synthesis under a decarboxylative reductive progress.

A Highly Efficient Dimeric Manganese-Catalyzed Selective Hydroarylation of Internal Alkynes.

We have developed a general and site-predictable manganese-catalyzed hydroarylation of internal alkynes in the presence of water, under an air atmosphere without the involvement of ligand. The unique catalytic feature of this reaction is highlighted by comparison with other widely used transition metal catalysts including palladium, rhodium, nickel, or copper. The simple operation, high efficiency and excellent functional group compatibility make this protocol practical for more than 90 structurally diverse internal alkynes, overcoming the influence of both electronic and steric effect of alkynes. Its exclusive regio- and chemoselectivity originates from the unique reactivity of the manganese-based catalyst towards an inherent double controlled strategy of sterically hindered propargyl alcohols without the installing of external directing groups. Its synthetic robustness and practicality have been illustrated by the concise synthesis of bervastatin, a hypolipidemic drug, and late-stage modification of complex alkynes with precise regioselectivity.

A Highly Efficient Dimeric Manganese‐Catalyzed Selective Hydroarylation of Internal Alkynes

AbstractWe have developed a general and site‐predictable manganese‐catalyzed hydroarylation of internal alkynes in the presence of water, under an air atmosphere without the involvement of ligand. The unique catalytic feature of this reaction is highlighted by comparison with other widely used transition metal catalysts including palladium, rhodium, nickel, or copper. The simple operation, high efficiency and excellent functional group compatibility make this protocol practical for more than 90 structurally diverse internal alkynes, overcoming the influence of both electronic and steric effect of alkynes. Its exclusive regio‐ and chemoselectivity originates from the unique reactivity of the manganese‐based catalyst towards an inherent double controlled strategy of sterically hindered propargyl alcohols without the installing of external directing groups. Its synthetic robustness and practicality have been illustrated by the concise synthesis of bervastatin, a hypolipidemic drug, and late‐stage modification of complex alkynes with precise regioselectivity.