Nitrogen-Containing Substrates

The incorporation of nitrogen-containing substrates into syngas chemistry offers a route to valuable nitrogen compounds. This field has not been explored extensively. By reacting syngas with ammonia the synthesis of acetonitrile is reported with 40 % conversion and 40-45 % selectivity ( ). Other possible reactions are listed... 

Unlike the case of metal amides where it was convenient to discuss synthesis in terms of the metal substrate, it is more informative for organoimido groups to consider synthetic methods as a function of the nitrogen-containing substrate or ligand that ultimately generates the NR groups. 

Redox Combined Photocatalytic Processes for Nitrogen-containing Substrates... 

This reaction was applied to a mixture of diastereoisomeric diols [113], For instance, a,cx -dimethyl-l,4-benzenedimethanol was treated with Ru complex 30 (S/C=25), Novozyme 435, and 4-chlorophenyl acetate (3 equiv) in toluene at 70 °C to give the R,R diacetate in >99% ee and the meso isomer (R,R meso=98 2) in 77% yield (Scheme 40). Reaction of 1,3-pentanediol and 1,4-hexanediol gave the corresponding R,R diacetate in >99% ee, while the R,R to meso ratio was lower than that of the aromatic diacetate. Nitrogen-containing substrates also gave the desired products in optically pure form. 

HLADH was applied for the reduction of a broad variety of substrates. The regeneration of NADH can be achieved by the ethanol coupled-substrate method [239]. Cyclic ketones are good substrates for this enzyme [137, 240, 241]. Heterocyclic compounds containing oxygen or sulfur are accepted, too [242 246], but nitrogen-containing substrates are inhibitors of HLADH, because they apparently complex with zinc in the active site of the enzyme [247],... 

Nitrogenase reduces N2 and several nitrogen-containing substrates to ammonia and amines. This assay uses a dabsyl precolumn derivatization method in quantitating the products. 

The synthesis of aziridine derivatives has received much attention in recent years, because these are versatile building blocks for synthesis for a wide range of nitrogen-containing substrates. Oxidation of N-aminophthalimide with lead tetraacetate in the presence of a variety of electrophilic and nucleophihc olefins is a useful, stereospecific route to aziridines (Scheme 13.46) [67]. 

The application of ligand 102 has successfully been extended to derivatiza-tions of nitrogen containing substrates. Arylation of the 2,3-dihydropyrrole 63 with phenyl triflate catalyzed by the 102-palladium complex [R=C(CH3)3] produced the single isomer 65 with 88% yield and in 85% ee [81]. 

If any of the urea cycle enzymes is missing, ammonia (the nitrogen-containing substrate of the cycle) cannot be metabolized. If any of the enzymes is defective (i.e., it does not catalyze its reaction at an appropriate rate), ammonia is metabolized slowly. Under both circumstances the body s ammonia concentration is excessively high. 

This reaction can be applied to several other diynes, including nitrogen-containing substrates and the enantiomerically pure diyne 4 derived from tartaric acid60. 

Typical examples for an oxygen- and nitrogen-containing substrate are given in reactions 70 and 71. 

Furthermore, it can be seen that reduction of CO2 can lead to various Cj-fuel products, and that carbon dioxide fixation in aqueous media is accompanied by the competitive H2-evolution process. Thus the developed catalysts must exhibit selectivity toward the desired product and respective substrate. In addition to carbon dioxide and water, nitrogen-containing compounds can be used as substrates for the reduced photoproduct. Several reduction processes of nitrogen-containing substrates are summarized as follows ... 

Very interesting results were obtained by Borszeky, Mallat, Baiker et al. in the enantioselective hydrogenation of nitrogen containing substrates. It was found that on Pd-alumina catalyst modified with Cnd, Cn, or ephedrine, the C=N bond in pyruvic acid oxime can be hydrogenated into... 

Thus, reaction of carbonimidoyl dihalides with a wide variety of nitrogen-containing substrates can be achieved, and the products obtained range from linear chloroformamidines, guanidines, and carbodiimides to five- and six-membered heterocycles. 

Two further examples for arylation reactions catalyzed by phosphinooxazoline-palla-dium complexes are shown in Scheme 31 with the formation of 129 and 131 as nitrogen-containing substrates arylation of the 2,3-dihydropyrrole 63 with phenyl triflate catalyzed by the palladium complex 120 (R = CMcs) gave the single isomer 65 in 88% yield and with 85% ee.[ i... 

Despite the stoichiometric requirements of expensive palladium salts, this reaction can be useful in the synthesis of ortho-foxmy -, A,A-dialkylaminomethyl-, and amino-substituted biaryls since variuos nitrogen containing substrates at benzylic position readily form palladacycles, e.g. A,A-dimethylbenzylamine, A-benzylidene-A ,A -dimethylhydrazone, O-methylbenzaldoximes, and A-acylanilines [17,18]. 

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