Purely aqueous-phase chemoselective reduction of a wide range of aromatic and aliphatic nitro substrates has been performed in the presence of inexpensive Ni- and Co-based nanoparticle catalysts using hydrazine hydrate as a reducing agent at room temperature. Along with the observed high conversions and selectivities, the studied nanoparticle catalysts also exhibit a high tolerance to other highly reducible groups present in the nitro substrates. The development of these potential chemoselective reduction catalysts also provides a facile route for the synthesis of other industrially important fine chemicals or biologically important compounds, where other highly reducible groups are present in close proximity to the targeted nitro groups.

An efficient NaNO2 /I2 -mediated one-pot transformation of Morita-Baylis-Hillman (MBH) acetates into alkyl 3-nitro-5-(aryl/alkyl)isoxazole-4-carboxylates is described. In a cascade event, initial Michael addition of NaNO2 to the MBH acetate furnishes the allylnitro intermediate which undergoes I2 -catalyzed oxidative α-CH nitration of the nitromethyl subunit followed by [3+2] cycloaddition to afford the title compounds. Structural elaborations of these highly substituted isoxazoles by SN Ar reactions and hydrogenolysis allows access to useful products.

A one-pot universal approach for transforming arylamines to aryl halides via reaction with sodium nitrite (NaNO ) and N-halosuccinimide (NXS) in DMF at room temperature under metal- and acid-free condition is described. This new protocol that is complementary to the Sandmeyer reaction, is suggested to involve the in situ generation of nitryl halide induce nitrosylation of aryl amine to form the diazo intermediate which is halogenated to furnish the aryl halide.

A metal-free nitration of the α-C-H to carbonyl in propiophenones was achieved with I2/NaNO2 in the presence of an oxidant in dimethyl sulfoxide (DMSO) as the medium. Conversely under similar conditions, reaction of acetophenones produced thiohydroximic acids via a radical-based cascade event which involves oxidative nitration of the α-carbon to a carbonyl followed by Michael addition of the thiomethyl group from DMSO and subsequent rearrangement. Besides DMSO, the scope of the reaction encompasses other symmetrical and unsymmetrical dialkylsulfoxides.

The antileishmanial activity of a variety of 3-nitro and 3-amino-isoxazoles against promastigote and amastigote stages of L. donovani is described.

Sodium nitrite (NaNO2) is a cheap inorganic reagent that has wide applications in synthetic organic chemistry. The Sandmeyer reaction for transforming amines into diazo derivatives and nitration, including the oxidative ones, are well known and globally used in several industrial processes too. Sodium nitrite is also used in the Nef reaction and Abidi transformation besides several other important reactions. The ability of NaNO2 to produce NO·, NO2, and N2O4 under oxidative conditions has considerably assisted in the discovery of its newer applications. Strikingly, this has resulted in remarkable development in reactions involving NaNO2 as either catalyst or reagent, and this review is an attempt to assimilate them. Wherever possible the mechanistic details associated with the reported reaction/transformation is provided.

An efficient protocol for transforming alkyl 3‐nitro‐5‐(aryl/alkyl)isoxazole‐4‐carboxylates into 3‐amino‐ and 3‐hydrazinyl‐5‐aryl/alkyl‐isoxazole‐4‐carboxylates is described. The reaction that is carried out in aqueous acetonitrile solution generally afford the products without any chromatographic purification. Investigations with the substrate scope reveal that this protocol is compatible only when the ester group is present at the C‐4 position of the isoxazole ring.magnified image

tert‐Butyl hydroperoxide (TBHP) served as the methyl source under metal‐free aerobic conditions in the oxidative amination of the C(sp3)–H bond to synthesize quinazolin‐4(3H)‐ones and quinazolines from 2‐aminobenzamides and 2‐carbonyl‐substituted anilines, respectively.