Nitrogen iron catalyzed

Recently, Taillefer et al. reported an Fe/Cu cooperative catalysis in the assembly of N-aryl heterocycles by C—N bond formation [90]. Similarly, Wakharkar and coworkers described the N-arylation of various amines with aryl halides in the presence of Cu—Fe hydrotalcite [91]. Interestingly, Correa and Bolm developed a novel and promising ligand-assisted iron-catalyzed N-arylation of nitrogen nucleophiles without any Cu co-catalysts (Scheme 6.19) [92]. Differently substituted aryl iodides and bromides react with various amides and N-heterocycles. The new catalyst system consists of a mixture of inexpensive FeCl3 and N,N -dimethylethylenediamine (dmeda). Clearly, this research established a useful starting point for numerous future applications of iron-catalyzed arylation reactions. 

An iron-catalyzed multicomponent reaction of aldehyde 4a, acetophenone, acetyl chloride and acetonitrile, which was used as the solvent, gave P-amino ketones such as 32 (Scheme 8.11) [41]. It was assumed that the sequence starts with an aldol reaction of aldehyde and ketone and then proceeds further with a displacement of a P-acetoxy group by the nucleophilic nitrile-nitrogen. 

Currently, all accumulating evidence indicate that asbestos is directly genotoxic by inducing DNA strand breaks by mechanisms that may include the generation of reactive oxygen and nitrogen species (catalyzed by iron), alteration in the mitochondrial function, and activation of death receptor pathway. Asbestos activates DNA repair enzymes such as, apurinic endonuclease and poly(ADP-ribose) polymerase (Upad-hyay and Kamp 2003). 

Efficient and regioselective iron-catalyzed aerobic oxidative reactions afforded 3,5-disubstituted isoxazoles 5 from homopropargylic alcohols 4, r-BuONO as the nitrogen source, and H2O under mild conditions (140L6298).A transition metal-free one-pot synthesis of 3,5-disubstituted isoxazoles used terminal alkynes by treatment with -BuLi, then aldehydes and iodine to afford intermediate a-alkynyl ketones 6 converted into isoxazoles 7 with hydroxylamine (14JOC2049). 

Finished product is stored in stainless steel or phenolic-lined carbon steel tanks, generally blanketed with nitrogen, all in an effort to avoid product discoloration associated with iron-catalyzed contact and oxidation. Narrow-range temperature control of the contents of the tank is vital to maintain the product in the molten state in case of those products with high freeze point (e.g., p-tcrt-butyl phenol) or a pumpable viscosity in the case of a long, branched-chain product (e.g., nonylphenol) while preventing thermal dealkylation. 

Because it can take two possible forms, iron is a sort of switch-hitter that can both absorb and eject electrons. This helps iron catalyze all sorts of reactions. Iron s central location in the Irving-Williams series makes it moderately sticky to oxygen, nitrogen, and sulfur. In chemistry, moderately sticky atoms are the best catalysts they bind to something, change it, then let it go. 

Nitrogen-directed C—H activation to form C—C bonds like aryl-aryl is a relatively recent class of reactions. In 2008, Nakamura and coworkers presented the first report of an iron-catalyzed C—H arylation reaction—a homogeneous iron catalysis featuring C—C bond formation via C—H activation. As an overall synthetic transformation, it was a formal nucleophilic displacement of the ort/ o-hydrogen atom by... 

Iron is an abundant, inexpensive, and environmentally benign metal in the first transition series with numerous important applications in a wide range of organic transformations and enzyme chemistry. In recent years, researchers have made impressive advances in the iron-catalyzed C-H bond activation [1]. These methods are successful through the formation of various C-C, C-N, and C-O bonds and have become prevalent and efficient tools to assemble valuable nitrogen- and oxygen-containing heterocycles. 

Iron-Catalyzed Synthesis of Nitrogen-Containing Heterocycles... 

Imidazopyridines are important nitrogen-containing heterocycles that show a wide range of bioactivities. Hajra and coworkers have developed an iron-catalyzed oxidative diamination of nitroalkene with 2-aminopyridine to access 2-nitro-3-arylimidazo[l,2- ]pyridines under mild and aerobic reaction conditions (Scheme 9.6) [8]. In particular, the method allows the formation of two new C-N bonds through sequential Michael addition and vinyl C(sp )-H/N-H functionalizations and represents the first example of employing molecular oxygen as the terminal oxidant for the selective C-H amination. 

Oxidation of sulfur dioxide in aqueous solution, as in clouds, can be catalyzed synergistically by iron and manganese (225). Ammonia can be used to scmb sulfur dioxide from gas streams in the presence of air. The product is largely ammonium sulfate formed by oxidation in the absence of any catalyst (226). The oxidation of SO2 catalyzed by nitrogen oxides was important in the eady processes for manufacture of sulfuric acid (qv). Sulfur dioxide reacts with chlorine or bromine forming sulfuryl chloride or bromide [507-16 ]. 

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