Microwave mediated reduction of heterocycle and fluorine containing nitroaromatics with Mo(CO)6 and DBU

Metal-Free, Rapid, and Highly Chemoselective Reduction of Aromatic Nitro Compounds at Room Temperature

In this study, we developed a metal-free and highly chemoselective method for the reduction of aromatic nitro compounds. This reduction was performed using tetrahydroxydiboron [B₂(OH)₄] as the reductant and 4,4'-bipyridine as the organocatalyst and could be completed within 5 min at room temperature. Under optimal conditions, nitroarenes with sensitive functional groups, such as vinyl, ethynyl, carbonyl, and halogen, were converted into the corresponding anilines with excellent selectivity while avoiding the undesirable reduction of the sensitive functional groups.

Microwave-assisted, Copper-free Sonogashira Coupling Between Aryl Halides and Terminal Alkynes Using Recyclable Ionic Liquid and Catalyst

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An efficient method for the Sonogashira coupling reaction between aryl halides and terminal alkynes has been developed. The reaction was performed in ionic liquid 1-butyl-3- methylimidazolium tetrafluoroborate ([Bmim][BF4]) under microwave irradiation. High yields of products were obtained in a very short reaction time. Moreover, the medium and catalyst could be recovered and reused three times without considerable decrease in reaction yields.

Nitroarenes as the Nitrogen Source in Intermolecular Palladium-Catalyzed Aryl C-H Bond Aminocarbonylation Reactions

A three-component palladium-catalyzed aminocarbonylation of aryl and heteroaryl sp² C-H bonds using nitroarenes as the nitrogen source was achieved using Mo(CO)₆ as the reductant and origin of the CO. This intermolecular C-H bond functionalization does not requires any exogenous ligand to be added, and our mechanism experiments indicate that the palladacycle catalyst serves two roles in the aminocarbonylation reaction: reduce the nitroarene to a nitrosoarene and activate the sp² C-H bond.

Pd-Catalyzed cycloisomerization/nucleophilic addition/reduction: an efficient method for the synthesis of spiro-pseudoindoxyls containing N,N′-ketal

An efficient method for the synthesis of C2-spiropseudoindoxyls was developed and a possible mechanism was given.

Environmentally benign selective hydrogenation of α,β-unsaturated aldehydes and reduction of aromatic nitro compounds using Cu based bimetallic nanoparticles supported on multiwalled carbon nanotubes and mesoporous carbon

The catalytic activity of these materials was investigated in the hydrogenation of α,β-unsaturated aldehydes and reduction of aromatic nitro compounds using different hydrogen sources.

Synthesis of hybrid anticancer agents based on kinase and histone deacetylase inhibitors

A HDAC, kinase inhibitor hybrid, (Z)-N1-(3-((1H-pyrrol-2-yl)methylene)-2-oxoindolin-5-yl)-N8-hydroxyoctanediamide, 6, showed impressive anticancer action in a number of biochemical and cell-based assays.

Quinoline and phenanthroline preparation starting from glycerol via improved microwave-assisted modified Skraup reaction

An efficient “green” modified Skraup reaction in neat water was developed using inexpensive, abundant and environmentally-friendly glycerol under microwave irradiation conditions.

Phosphane-free green protocol for selective nitro reduction with an iron-based catalyst

Iron phthalocyanine with iron sulfate has been successfully applied for high chemo- and regioselective reduction of aromatic nitro compounds to give the corresponding amines in a green solvent system without using any toxic ligand. The catalytic systems were also compatible with a large range of other reducible functional groups, such as keto, acid, amide, ester, halogen, lactone, nitrile, N-benzyl, O-benzyl, hydroxy, and heterocycles. In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield. In most of the cases the conversion and selectivity was greater than 99% as determined by GC-MS analysis.

Synthesis and biological evaluation of 1,4-benzodiazepin-2-ones with antitrypanosomal activity

A library of 1,4-benzodiazepines has been synthesized and evaluated against Trypanosoma brucei, a causative parasite of Human African trypanosomiasis. Benzodiazepines possessing a P2- transporter motif were found to have MIC values as low as 0.78 μM.

Microwave-mediated synthesis of an arylboronate library

A series of arylboronates has been synthesized from the reaction of 2-(2-, (3-, or (4-(bromomethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 1{1-3} respectively with a range of N-, S-, and O-nucleophiles, using microwave-mediated chemistry. For the synthesis of N- and S-substituted boronates, a supported base, PS-NMM, was employed, and many reactions were complete within 15 min. With O-nucleophiles, a mixture of tetrabutylammonium bromide, potassium carbonate, and sodium hydroxide was employed. The resulting aminomethyl, mercaptomethyl, or alkoxy-/phenoxymethyl-arylboronates were subjected to microwave-mediated Suzuki Miyaura coupling reactions to afford a range of biaryls in moderate to good yields. The X-ray structures of five boronates were determined.

Research Spotlight: Microwave chemistry enabling the synthesis of biologically relevant amines

Microwave-mediated chemistry, involving the reduction of nitroarenes with molybdenum hexacarbonyl as a stoichiometric reducing agent, has been employed in the synthesis of a range of anilines. Many of these reactions exhibit high levels of chemoselectivity, tolerating unsaturation, steric hindrance and halide substituents (I, Br, Cl or F), although the latter, under certain circumstances, can be displaced in concomitant SNAr/reduction processes. The reduction chemistry has been combined with palladium-catalyzed coupling and also used in the synthesis of important intermediates to kinase inhibitors or molecules with submicromolar antitrypanosomal activity. In selected cases, microwave-mediated routes have been compared with thermal (traditional oil bath) and flow reactor-mediated chemistries.

Highly chemo- and regioselective reduction of aromatic nitro compounds using the system silane/oxo-rhenium complexes

The reduction of aromatic nitro compounds to the corresponding amines with silanes catalyzed by high valent oxo-rhenium complexes is reported. The catalytic systems PhMe(2)SiH/ReIO(2)(PPh(3))(2) (5 mol %) and PhMe(2)SiH/ReOCl(3)(PPh(3))(2) (5 mol %) reduced efficiently a series of aromatic nitro compounds in the presence of a wide range of functional groups such as ester, halo, amide, sulfone, lactone, and benzyl. This methodology also allowed the regioselective reduction of dinitrobenzenes to the corresponding nitroanilines and the reduction of an aromatic nitro group in presence of an aliphatic nitro group.