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A Pd(II)-catalyzed peroxide-free ortho aroylation of directing arenes has been developed via cross dehydrogenative coupling (CDC) in the presence of the terminal oxidant Cu(OAc)2·H2O. Ortho aroylation of directing arenes proceeds via decarbonylation of the in situ generated phenyl glyoxal, which is obtained from 2-acetoxyacetophenone in the presence of the oxidant Cu(OAc)2·H2O. However, changing the oxidant to CuX2 (X = Cl, Br) provided exclusive di-ortho-halogenated 2-arylbenzothiazoles. During the halogenation, CuX2 served the dual role of a halogen source as well as a co-oxidant.

A mild approach for direct C2 sulfonylation of heteroaromatic N-oxides with sulfonyl hydrazides affording 2-sulfonyl quinolines/pyridines has been developed. A variety of heteroaromatic N-oxides and sulfonyl hydrazides participate effectively in this transformation which uses hypoiodites (generated in situ from NaI and TBHP) as a means of substrate activators. In this reaction, the N-oxide plays a dual role, acting as a traceless directing group as well as a source of oxygen atom.

A novel method toward synthesis of sulfonamides and β-arylsulfonyl enamines has been developed via I2/TBHP mediated C–N and C–H bond cleavage of tertiary amines, which features highly selective formation of two different target products depending on the reaction solvent. The experimental results reveal that H2O as the solvent could effectively achieve the C–N bond cleavage to produce sulfonamides due to H2O participating in the reaction process where H2O plays a dual role. Differing from H2O, organic solvents (such as dimethyl sulfoxide) could promote the C–H bond cleavage of tertiary amines to yield β-arylsulfonyl enamines.

An iron-catalyzed radical [2 + 2 + 2] annulation of benzene-linked 1,7-enynes with aldehydes has been developed. With this method, a variety of fused [6.6.6] pyran molecules are built in an efficient and selective manner. The aldehydic radical-mediated strategy exhibits a particularly attractive dual role, which triggers and terminates the domino cyclization.

The Acceptorless Dehydrogenative Coupling (ADC) of alcohols with amines is reported using a heterogeneous Fe-catalyst. The reaction operates under mild conditions with the liberation of dihydrogen and water as the byproducts. The developed ADC strategy is simple, efficient, exhibits wide functional group tolerance and can be scaled up. The present catalytic approach possesses a dual role; acting as a catalyst as well as being magnetically separable. The sustainable reuse of a heterogeneous iron catalyst is also shown.

With SmI3 as the Lewis acid and catalyzed by CuI in DMF, α-haloketones were transformed unexpectedly into α-hydroxy-1,4-diketones in good to moderate yields. The mechanism was probed and a plausible reaction pathway was proposed. DMF was assumed to play a dual role both as a hydroxyl source and as a solvent.

A novel, metal-free, and regioselective approach for the synthesis of isoxazoline/cyclic nitrone-featured methylenes has been developed by the reaction of readily accessible β,γ- and γ,δ-unsaturated ketoximes with TEMPO via tandem iminoxyl radical-promoted cyclization/TEMPO-mediated Cope-like elimination, respectively. This protocol utilizes commercially available TEMPO as the iminoxyl radical initiator as well as the β-hydrogen acceptor in the Cope-like elimination.

Copper-catalyzed regioselective C-3 sulfenylation of imidazo[1,2-a]pyridines using p-tosylchloride as a benign source of sulfenylating agents has been developed. On the other hand, p-tosylchloride mediated thiomethylation of imidazo[1,2-a]pyridines with dimethylsulfoxide as a source of thiomethylation under metal-free conditions was also described.

A new organocatalytic approach for the synthesis of peroxides based on СН activation of a sp3-hybridized carbon atom is reported. Peroxides were prepared in 31–89% yield by the reaction of malonates, β-ketoesters, and cyanoacetic esters with a Bu4NI/tert-butyl hydroperoxide system. The formation of the expected hydroxylation products was not observed. In the discovered reaction, tert-butyl hydroperoxide plays a dual role by acting as the oxidant and the O-reagent for the C–O coupling. The synthesis can be scaled up to generate gram quantities of the target products.

A novel complex system generated in situ from Mo(CO)6 and an amine is described for the regiospecific aminocarbonylation of various terminal alkynes. The Mo(CO)6–amine system played a dual role as complexing agent and as CO donor, thus making this process palladium-free.

The title synthesis proceeds via an elimination/umpolung/protonation sequence and doesn′t apply to the synthesis of alkyl-acetylenes.

A novel amine-catalyzed nucleophilic trifluoromethylthiolation between Morita–Baylis–Hillman carbonates and O-octadecyl-S-trifluorothiolcarbonate has been developed. The regioselectivity of this reaction can be controlled by choosing different solvents, affording primary allylic SCF3 products in THF and secondary allylic SCF3 products in CHCl3 as major products. The mechanistic investigation indicated that DABCO plays a dual role in activating the Zard's trifluoromethylthiolation reagent and the MBH carbonates.

An unprecedented silver-catalyzed cascade reaction of tosylmethyl isocyanide (TosMIC) with propargylic alcohols for the efficient synthesis of (E)-vinyl sulfones has been developed where TosMIC plays a dual role as both the reactant in the allenylation of propargylic alcohols and the sulfonyl source.

See the light of day: Light is the fastest way of transferring energy and information through space, and in chemistry it can perform the dual role of reactant and product. Sunlight, a really unique reactant, represents our ultimate energy source. Chemists are engaged in designing systems for the conversion of light into electrical or chemical energy and vice versa to create a more sustainable way of life.

Iron(III)-mediated radical nitration of bisarylsulfonyl hydrazones is described. In this protocol, the nontoxic and inexpensive Fe(NO3)3·9H2O plays a dual role as catalyst as well as nitro source. The mild conditions, broad substrate scope, and the functional group compatibility are the significant features. The reaction pathway has been demonstrated using DFT calculations, and the products can be subsequently converted into oximes using SnCl2·2H2O in high yields.

The first example of Rh(III)-catalyzed cyclization of arylnitrones to indolines under external oxidant-free conditions is presented. An intermolecular coupling of arylnitrones with internal alkynes is made possible by the dual role of the Cp*Rh(III) catalyst mediating both the C–H bond activation and O-atom transfer. Synthetically important and pharmacologically privileged indoline derivatives were obtained in good yields with high diastereoselectivity.

The dual role of D-mannose as ligand for the Pd-catalyzed cross-coupling and as hydrogen source for the nitro reduction is demonstrated.

Dual role for catalysts: Novel routes for the generation of asymmetric stereocenters using photoredox catalysis were recently developed. Different chiral catalytic systems allowed new CC bonds to form in good yields and enantioselectivities using a mild methodology in which light is used as the energy source.

The applied Ru catalyst serves the dual role of an efficient hydrogen transfer catalyst and is a suitable Friedlaender annulation catalyst.

A tert-butyl peroxybenzoate (TBPB)-promoted direct α-methylation of 1,3-dicarbonyl compounds has been developed, providing α-methyl derivatives in moderate to good yields. In this procedure, TBPB plays a dual role, serving as both the methyl source and radical initiator. This work represents a key complement to the traditional α-methylation of 1,3-dicarbonyl compounds using methyl iodide.

The first additive-free method for the formation of bromo-substituted alkynyl sulfides (III) is reported.

A new silver-catalyzed heteroaromatization of propargylic alcohols with p-toluenesulfonylmethyl isocyanide (TosMIC) has been developed that provides an efficient and modular approach to sulfonyl benzoheteroles. For the first time, TosMIC plays a dual role in one reaction: sulfonyl source and ligand. An unprecedented deoxysulfonylation/hydration/condensation reaction pathway is disclosed.

Combination of iron(III) chloride and diorganyl diselenides was used for cyclization of arylpropiolates and arylpropiolamides in formation of 3-organoselenyl-2H-coumarins and 3-organoselenyl-quinolinones, respectively. Systematic study to determine the ideal conditions revealed that the two substrates reacted in the same way using identical reaction conditions. The versatility of this method has been demonstrated by extension of the best reaction conditions to substrate having a variety of substituents. Analyses of the optimization reaction also showed that diorganyl diselenides have a dual role by acting as cycling agent and base to restore the aromatic system. Mechanistic investigation studies and analyses of the products obtained have revealed that the cyclization reactions follow an initial 6-endo-dig process to give the six-membered heterocycles without involving an intramolecular ipso-cyclization route.

Glyoxylic acid (II) serves as a reactant and the catalyst, thus playing a dual role in this novel and robust metal-free reaction.

Quinoline N-oxides were found to undergo Cp*Rh(III)-catalyzed coupling with internal diarylalkynes to provide 8-functionalized quinolines through a cascade process that involves remote C–H bond activation, alkyne insertion, and intramolecular oxygen atom transfer. In this reaction, the N-oxide plays a dual role, acting as a traceless directing group as well as a source of oxygen atom, as confirmed by an 18O-labeling experiment.

Magnetic nanoparticles have become increasingly attractive in the field of catalysis over the last decade as they combine interesting reactivity with an easy, economical and environmentally benign mode of recovery. Early strategies focused on the use of such nanoparticles as a vehicle for supporting other catalytic nanomaterials or molecules to facilitate recovery. More recently, research has shown that bare magnetic nanoparticles may serve the dual role of a catalyst and a magnetically recoverable entity. At the same time, emerging sustainability concepts emphasize the utility of earth abundant and less toxic resources, especially iron. Herein, we review the recent progress made in the assembly of such systems and their direct application in catalysis. Examples of such bare nanoparticles include iron oxide (Fe2O3 and Fe3O4), metal ferrites (MFe2O4, M = Cu, Co and Ni), Fe(0), Co(0), Ni(0), and multi-component nanoparticles. Features such as reactivity, recoverability and leaching are discussed in a critical fashion.

Chloromethyllithium carbenoid has been chemoselectively added to cyclic enones (5-, 6- and 7-membered systems, including two natural products) to provide chloromethyl allylic alcohols. Under the optimized reaction conditions neither concomitant (n+1) homologation nor conjugate addition or Simmons–Smith-like cyclopropanation takes place. The presence of LiBr is estimated to play a dual role, namely as a carbenoid stabilizer and mild Lewis acid activator of the CO group. Notably, the mesomeric effect caused by β-heteroatom-containing substituents promotes the attack of the reagent at the most activated position.

Water-promoted ortho-selective monohydroxymethylation of phenols in the NaBO2 system generates salicyl alcohols in 65–97% yields. A remarkable rate-enhancement by water was observed, and NaBO2 appeared to serve the dual role of a suitable base and an efficient chelating reagent. This protocol possesses many advantages such as short reaction times, expanded substrate scope, and high mono- and regio-selectivities. The experimental results were explained by the calculations based on local ionisation energy minima, leading to a possible reaction mechanism.

The title compounds (IV) (18 examples) are obtained via a multicomponent reaction in the presence of the task-specific ionic liquid [DBU][AcOH], which plays the dual role of both catalyst and reaction medium.

The solid support plays a dual role as it eliminates the use of an organic solvent as well as a Pd-catalyst.

An alternative convenient approach for the bromination of various poly-substituted 4-pyridones has been developed via an oxidative nuclear bromination in the presence of sole pyridinium bromochromate (PBC). The PBC performs the dual role of oxidant and source of Br+ during the process. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

cis-1,4-Disubstituted morpholines are stereoselectively obtained by Bi(O-Tf)3-catalyzed ring closing O-allylation under mild reaction conditions without the need of any base.

It is assumed that copper is involved both in the generation of “CN” units from DMF-ammonia and in the cyanation of aryl iodides (I).

Copper plays a dual role: to coordinate both the aryl and fluoride ligands and to serve as an oxidant generating the reactive Cu(III) key intermediate.

A series of terminal alkenes (III) is synthesized by reaction of allylsamarium bromide (II) with aldehydes (I).

BF3·H2O plays a dual role, as an efficient non-oxidizing Broensted acid catalyst as well as an effective solvent making the reaction more economic and environmentally safe.

A virtually salt-free and straightforward bimolecular assembly giving N-unsubstituted pyrroles through fully unmasked intermediately formed α-amino aldehydes, which is enabled by the dual effects of a catalytic ruthenium complex and an alkali metal base, is reported.

A one-pot protocol is developed for the synthesis of various title systems via three- component domino coupling of 6-aminouracil or 4-aminocoumarin with 1,3-diketo compounds and isatins.

Phthalimide (I) plays a dual role in the oxidative cross-coupling reaction with alkylarenes (II) and (IV).

CaCO3 plays a dual role in the hydrogenation reaction - removing the acid generated during the formation of the catalyst and maintaining the activity of the catalyst.

We present a simple, mild, and highly effective method for the direct conversion of primary alcohols to carboxylic acids. TPAP serves as the catalyst, and NMO·H2O plays a dual role, acting as the co-oxidant and as a reagent for aldehyde hydrate stabilization. This previously unknown stabilizing effect of geminal diols by N-oxides is the key for the efficiency of the overall transformation.

The dual role of Selectfluor both as an oxidant and a source of fluoride to activate the arylsilanes avoids the need of an additional activator.

The ionic liquids play a dual role of green solvent as well as efficient and recyclable catalyst.

The title compound displays the dual role of an α,α′-acetone dianion4 and an allene 1,2-dipole5 equivalent allowing the preparation of versatile synthetic intermediates10a-c and11a-d (Tables 1 and2).

The diastereoselectivity of radical processes involving 1,3-diols is increased significantly with a simple and efficient strategy using the exocyclic effect. Boronate derivatives are successfully formed in situ by treatment of an equimolar amount of Et3B in the presence of oxygen. This step is followed by the mediation of a carbon-centered radical α to the cyclic boronate to give the anti reduced product with high stereocontrol. The sequence is also extended to β-amino alcohols.

Regioselective double bond cleavage within 5, required for access to the trans-fused perhydroazulene framework of pseudolaric acid A (1), has been accomplished via a highly diastereoselective intramolecular bromoetherification process, the latter serving a dual role as a protecting group tactic.

Results obtained over the past decade towards the preparation of multitopic carbohydrate architectures combining the molecular inclusion capabilities of cyclomaltooligosaccharide receptors (cyclodextrins, CDs) and the recognition properties of saccharide ligands towards biological receptors are discussed. The potential of these new sugar-based "intelligent" transporters for site specific delivery of therapeutics is outlined.