Gold‐Catalyzed Synthesis of Functionalized Pyridines by Using 2H‐Azirines as Synthetic Equivalents of Alkenyl Nitrenes

2H‐Azirines are easily synthesized from the corresponding ketones and, despite possessing a C?N bond embedded in a strained three‐membered cycle, they are sufficiently stable to be isolated, stored, and manipulated. 2H‐Azirines can be regarded as valuable synthetic equivalents of alkenyl nitrenes, however, reactions capitalizing on the cyclic strain of the heterocyclic motif and involving the cleavage of the C? N single bond remain surprisingly limited. A gold‐catalyzed reaction that allows the formation of polysubstituted functionalized pyridines from easily accessible 2‐propargyl 2H‐azirine derivatives was developed. This transformation, which corresponds to an unprecedented intramolecular transfer of an alkenyl nitrene to an alkyne, proceeds with low catalyst loading, is efficient, and exhibits a high functional‐group tolerance and a wide substrate scope.     

Microwave Promoted,Sodium Acetate Catalyzed One Pot Synthesis of Poly Functionalized 4H‐Pyrans

A clean and efficient one pot synthesis of 4H‐pyran derivatives through condensation of aromatic aldehydes, malononitrile and dicarbonyl compounds under microwave irradiation in presence of Sodium acetate as a catalyst is described.     

A Pd‐Catalyzed Synthesis of Functionalized Piperidines

A readily available cyclic carbamate 1 functions as a general precursor to a range of functionalized piperidine products via a new Pd‐catalyzed annulation strategy. An asymmetric catalytic variant provides a rapid and efficient means to access these heterocycles with high to excellent levels of enantiocontrol. Finally, these richly functionalized compounds are amenable to further chemoselective elaboration.     

Palladium‐Catalyzed Oxidative Synthesis of Highly Functionalized Ortholactones

A palladium‐catalyzed oxidative reaction is reported which converts dihydropyrans to their corresponding ortholactone. The products are formed in good to excellent yields with a very high level of chemoselectivity and functional group tolerance. Mechanistic studies confirm that the reaction proceeds by a Wacker‐type mechanism.     

One‐pot Three‐component Route for the Synthesis of Functionalized 4H‐chromenes Catalyzed by ZrOCl2·8H2O in Water

An efficient method for the synthesis of functionalized 4H‐chromenes via a one‐pot three‐component condensation reaction of a 2‐hydroxybenzaldehyde with an active methylene compound and a carbon‐based nucleophile in the presence of a catalytic amount of ZrOCl₂·8H₂O in water under thermal condition has been described. High yields, simple work‐up procedure, performing reactions in water and synthesis of complex molecules with a one‐pot procedure are the main advantages of this procedure. In addition, the structure of the product from the condensation of salicylaldehyde, 2‐naphthol, and dimedone was confirmed by X‐ray crystallography.     

Efficient Synthesis of Functionalized Thienocarbazoles Catalyzed by l‐proline

A new synthetic route has been developed for the synthesis of highly substituted thienocarbazoles via l ‐proline mediated Gewald reaction. The approach offers the advantages of clean reaction, simple methodology, high yield, easy purification, and economic availability of the catalyst.     

Copper(I)‐Catalyzed Interrupted Click Reaction: Synthesis of Diverse 5‐Hetero‐Functionalized Triazoles

The 5‐heterofunctionalized triazoles are important scaffolds in bioactive compounds, but current click reactions (CuAAC) cannot produce these core structures. A copper(I)‐catalyzed interrupted click reaction to access diverse 5‐functionalized triazoles is reported. Various 5‐amino‐, thio‐, and selenotriazoles were readily assembled in one step in high yields. The reaction proceeds under mild conditions with complete regioselectivity. It also features a broad substrate scope and good functional group compatibility.     

Pt‐Catalyzed Synthesis of Functionalized Symmetrical and Unsymmetrical Disilazanes

In nearly every total synthesis, silylating agents are employed in synthetic steps to protect sensitive functional groups. A Pt‐catalyzed hydrosilylation of various unsaturated substrates to prepare novel symmetrical and unsymmetrical disilazanes is described. The developed synthetic methodology is widely applicable and tolerates all manner of functional groups (e.g., amines, ethers, esters, halogens, silanes, etc.). To demonstrate the value of the described method, mono‐substituted 1,1,3,3‐tetramethyldisilazanes were further selectively converted to completely new unsymmetrical derivatives.     

Synthesis of Functionalized Vinylgermanes through a New Ruthenium‐Catalyzed Coupling Reaction

Vinyl‐substituted germanes react stereo‐ and regioselectively with olefins in the presence of complexes containing Ru? H and Ru? Ge bonds with the formation of functionalized vinylgermanes that cannot be synthesized by olefin cross‐metathesis procedures. The reaction opens a new catalytic route for preparation of a class of organogermanes that are potent organometallic reagents for organic synthesis because they show very low toxicity and could replace organotin compounds. The mechanism of this new catalytic route was proven to involve an interesting insertion of the vinylgermane into the Ru? H bond and β‐Ge transfer to the metal with elimination of ethylene and generation of an Ru? Ge bond, followed by insertion of the alkene into the Ru? Ge bond and β‐H transfer to the metal to eliminate the substituted vinylgermane.     

Palladium‐Catalyzed Oxidative Cycloisomerization of 2‐Cinnamyl‐1,3‐Dicarbonyls: Synthesis of Functionalized 2‐Benzyl Furans

A new palladium‐catalyzed intramolecular oxidative cycloisomerization of readily available starting materials, 2‐cinnamyl‐1,3‐dicarbonyls, has been demonstrated for the creation of structurally diverse 2‐benzyl furans. The cycloisomerization occurs by a regioselective 5‐exo‐trig pathway. The reaction shows a broad substrate scope with good to excellent yields. Furthermore, a one‐pot procedure has been executed by using readily available cinnamyl alcohols and 1,3‐diketones.     

Iron Salts in the Catalyzed Synthesis of 5‐Substituted 1H‐Tetrazoles

Clicking iron : Cheap and environmentally friendly [Fe(OAc)₂] is used for the catalysis of cycloadditions between aryl nitriles and trimethylsilyl azide to prepare substituted 1H‐tetrazoles in good yield (see scheme).

     

A Novel and Regiospecific Synthesis of 1‐Aryl‐1H‐benzotriazoles via Copper(I)‐Catalyzed Intramolecular Cyclization Reaction

1‐Aryl‐1H‐benzotriazole derivatives were synthesized via intramolecular cyclization of easily obtained triazenes, using CuI as the catalyst, DMSO as the solvent, t‐BuONa as the base, and 1,10‐phenanthroline as the ligand, in up to 97% yield. The synthesis is regiospecific and functional group‐tolerant.     

Synthesis of 1H‐Imidazoles Catalyzed by Cu‐Nanoparticle and Its Physicochemical Properties

Series of 1‐arylmethyl‐4, 5‐dihydro‐2‐aryl‐1H‐imidazole were synthesized expeditiously in good yields from 1,2‐diaminoethane and aromatic aldehydes in the presence of Cu nanoparticle under microwave irradiation in solvent‐free method. Monodisperse spherical Cu nanoparticles with a diameter range of 45 ± 8 nm were synthesized by polyol process. The particle size and elemental structure of copper nanoparticles were confirmed by XRD data and was found to be having a face‐centered cubic structure. The resulting substituted imidazoles have been studied in the achievement of degree of drug absorption enhancement as well as the potential associated toxicity on the basis of hypothetical antibacterial pharmacophores and structures that were designed to interact with both of gram‐positive and gram‐negative bacteria. All the synthesized molecules were characterized on the basis of 1H NMR, 13C NMR, mass spectrometry, and elemental data.     

Palladium‐Catalyzed Carbonylation of 2‐Bromoanilines with 2‐Formylbenzoic Acid and 2‐Halobenzaldehydes: Efficient Synthesis of Functionalized Isoindolinones

A concise and highly versatile method for the synthesis of functionalized isoindolinones is reported. Various 2‐bromoanilines undergo palladium‐catalyzed carbonylation with 2‐formylbenzoic acid under a convenient and mild procedure to give good to excellent yields of the corresponding isoindolinones. Additionally, 2‐halobenzaldehydes can be applied as substrates in palladium‐catalyzed double‐carbonylation to provide identical compounds in moderate to good yields.