Nitro-heterocycles

The polarographic half-wave reduction potential of 4-nitroisothiazole is -0.45 V (pH 7, vs. saturated calomel electrode). This potential is related to the electron affinity of the molecule and it provides a measure of the energy of the LUMO. Pulse radiolysis and ESR studies have been carried out on the radical anions arising from one-electron reduction of 4-nitroisothiazole and other nitro-heterocycles (76MI41704). 

Typical VNS reacdon of nitro heterocycles are presented in Eq. 9.28-9.31. Nitrofurans and nitropyrroles are less reacdve toward VNS reacdons than nitrothiophenes. 

A recent communication is based on the nucleophilic substitution of N-silylated iminophosphoranes (Scheme 8), where activated chloro- (12) and nitro heterocycles (13) (triazines, pyrazines, and pyridines) are transformed into monosubstituted iminophosphoranes (14). Of special advantage are the mild reaction conditions and the preferential formation of monosubstituted... 

Olah" has conducted extensive studies into transfer nitration with A-nitro heterocycles. Studies were conducted into the effect of the heterocycle and its counterion on reactivity towards aromatic substrates. 

The arylation of nitrite and azide anions as well as some amines can be of synthetic interest in some instances for example, difuryl, dithienyl and diselenophyl iodonium salts were useful substrates for the preparation of the corresponding nitro heterocycles [61]. Diphenyliodonium 2-carboxylate transferred its carboxy-late-bearing ring with high specificity to several anilines in a reaction especially suitable for the preparation of weakly basic and sterically hindered A-arylanthranilic acids. 

A great number of publications deal with the reaction of nitration [7-20], At the same time, volumes literature on nitro heterocycles has not been systematized until the present time. Direct nitration of some five-membered heterocycles such as pyrroles, furans, thiophenes, pyrazoles, imidazoles, and thiazoles has been discussed by Katritzky [21, 22], Some synthetic routes to nitrated six-membered nitrogen-containing aromatic heterocycles [23], as well as the nitration of oxo-pyrimidines and -imidazoles [24], and quantum-chemical studies of the nitration of benzazoles [25] have been reported. 

In view of the usefulness of a variety of nitro-heterocycles, especially as antiprotozoal and antibacterial agents, some of these otherwise inaccessible derivatives might exhibit advantageous therapeutic properties. 

Nitrobenzofurans (21) have been obtained by the condensation of substituted salicylaldehydes with bromonitromethane,18,19 a versatile reagent useful for the synthesis of various other nitro-heterocycles. The yields however, are variable (5-52%) [Eq. (3)]. 

Low reactivity of pyridine compared with benzene at carbon Reaction at nitrogen prevails Formation of stable complexes with electrophiles A-Nitro Heterocycles as Nitrating Agents... 

Rocheleau S et al., Toxicity of Nitro-Heterocyclic and Nitroaromatic Energetic Materials to Terrestrial Plants in a Natural Sandy Loam Soil, Technical Report No. ECBC-TR-351, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, 2005. 

Simini M et al., Reproduction and survival of Eiseniafetida in a sandy loam soil amended with the nitro-heterocyclic explosives RDX and HMX, Pedobiologia, 47, 657, 2003. 

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