Carbonyl compounds nitrogen derivatives

Usually, the reactions of carbonyl compounds and derivatives of ammonia are considered to be concluded with the formation of the imino derivative (156), but there is evidence that the C=N double bond may react faster than the C=0 group with nitrogen nucleophiles to form 1,1-diamino derivatives (Scheme 47). 

In the oxaziridines (1) ring positions 1, 2 and 3 are attributed to oxygen, nitrogen and carbon respectively. The latter almost always is in the oxidation state of a carbonyl compound and only in rare cases that of a carboxylic acid. Oxaziridinones are not known. The nitrogen can be substituted by aryl, alkyl, H or acyl the substituent causes large differences in chemical behavior. Fused derivatives (4), accessible from cyclic starting materials (Section 5.08.4.1), do not differ from monocyclic oxaziridines. 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

Nitro compounds are versatile precursors for diverse functionalities. Their conversion into carbonyl compounds by the Nef reaction and into amines by reduction are the most widely used processes in organic synthesis using nitro compounds. In addition, dehydration of primary nitro compounds leads to nitrile oxides, a class of reactive 1,3-dipolar reagents. Nitro compounds are also good precursors for various nitrogen derivatives such as nitriles, oximes, hydroxylamines, and imines. These transformations of nitro compounds are well established and are used routinely in organic synthesis. 

As discussed in Chapter 6, nitro compounds are converted into amines, oximes, or carbonyl compounds. They serve as useful starting materials for the preparation of various heterocyclic compounds. Especially, five-membered nitrogen heterocycles, such as pyrroles, indoles, and pyrrolidines, are frequently prepared from nitro compounds. Syntheses of heterocyclic compounds using nitro compounds are described partially in Chapters 4, 6 and 9. This chapter focuses on synthesis of hetero-aromatics (mainly pyrroles and indoles) and saturated nitrogen heterocycles such as pyrrolidines and their derivatives. 

The carbonylation of imidazole derivatives with several olefins takes place in high yields with the aid of an Ru3(CO)i2 catalyst.112,112a The carbonylation occurs exclusively at the a-position to the sp2 nitrogen (Equation (85)). A wide range of olefins can be utilized in this reaction, and a variety of functional groups are compatible under the reaction conditions. The (/i-H)triruthenium clusters such as 12 are proposed as a key species in this carbonylation reaction. Other five-membered A-heteroaromatic compounds, such as pyrazoles, oxazoles, and thiazoles, can be used for the carbonylation reactions, where the carbonylation takes place at the a-C-H bond to the sp2 nitrogen. 

In contrast to the rich chemistry of alkoxy- and aryloxyallenes, synthetic applications of nitrogen-substituted allenes are much less developed. Lithiation at the C-l position followed by addition of electrophiles can also be applied to nitrogen-containing allenes [10]. Some representative examples with dimethyl sulfide and carbonyl compounds are depicted in Scheme 8.73 [147, 157]. a-Hydroxy-substituted (benzotriazo-le) allenes 272 are accessible in a one-pot procedure described by Katritzky and Verin, who generated allenyl anion 271 and trapped it with carbonyl compounds to furnish products 272 [147]. The subsequent cyclization of 272 leading to dihydro-furan derivative 273 was achieved under similar conditions to those already mentioned for oxygen-substituted allenes. 

A wide range of carbon, nitrogen, and oxygen nucleophiles react with allylic esters in the presence of iridium catalysts to form branched allylic substitution products. The bulk of the recent literature on iridium-catalyzed allylic substitution has focused on catalysts derived from [Ir(COD)Cl]2 and phosphoramidite ligands. These complexes catalyze the formation of enantiomerically enriched allylic amines, allylic ethers, and (3-branched y-8 unsaturated carbonyl compounds. The latest generation and most commonly used of these catalysts (Scheme 1) consists of a cyclometalated iridium-phosphoramidite core chelated by 1,5-cyclooctadiene. A fifth coordination site is occupied in catalyst precursors by an additional -phosphoramidite or ethylene. The phosphoramidite that is used to generate the metalacyclic core typically contains one BlNOLate and one bis-arylethylamino group on phosphorus. 

Varieties of primary and secondary alcohols are selectively oxidized to aldehyde or carbonyl compounds in moderate to excellent yields as summarized in Table 3. As can be seen, /(-substituted benzyl alcohols (e.g., -Cl, -CH3, -OCH3, and -NO2) yielded > 90% of product conversion in 3-4 h of reaction time with TOP in the range of 84-155 h (entries 2-5, Table 3), Heterocyclic alcohols with sulfur- and nitrogen-containing compoimds are found to show the best catalytic yield with TOP of 1517 and 902 h for (pyrindin-2-yl)methanol and (thiophene-2-yl) methanol, respectively (entries 9 and 10, Table 3). Some of aliphatic primary alcohols (long chain alcohols) and secondary alcohols (cyclohexanol, its methyl substituted derivatives and norboman-2-ol) are also selectively oxidized by the membrane catalyst (entries 11-14 and 15-17, Table 3) with TOP values in the window of 8-... 

This methodology is also an important and potentially valuable method for C—N bond formation using the amination of carbon nucleophiles with electrophilic nitrogen transfer reagents (Scheme 1) Amination of ordinary carbanions and a-carbanion derived from carbonyl compounds and nitriles provides an important method for the synthesis of amines and a-amino carbonyl compounds and nitriles", respectively. For this purpose, a number of electrophilic amination reagents, which are synthetic equivalents of the R2N+ synthon, have been developed and the synthetic potential of electrophilic amination of carbon nucleophiles has been studied in detail . ... 

However, these compounds are generally unstable. Most imines with a hydrogen on the nitrogen spontaneously polymerize.143 Stable hemiaminals can be prepared from polychlorinated and polyfluorinated aldehydes and ketones, and diaryl ketones do give stable imines Ar2C=NH.144 Aside from these, when stable compounds are prepared in this reaction, they are the result of combinations and condensations of one or more molecules of 12 and/or 13 with each other or with additional molecules of ammonia or carbonyl compound. The most important example of such a product is hexamethylenetetramine145 (11), prepared from ammonia and formaldehyde.146 Aromatic aldehydes give hydrobenzamides ArCH(N=CHAr)2 derived from three molecules of aldehyde and two of ammonia.147... 

The dithioacetal (0.01 mol) was stirred for a few hours at room temperature with clayfen (4) (10.4 g, 11 mmol of ferric nitrate) or with claycop (12.1 g, 20 mmol of copper nitrate) in toluene, n-pentane or, preferably, dichloromethane (120ml). Evolution of nitrogen oxides occurred rapidly. Stirring was maintained until gas evolution ceased. The clay was then filtered off and washed twice with portions (50 ml) of the solvent. The resulting pale-yellow or slightly green solution was filtered through a small quantity of neutral aluminium oxide and the solvent was evaporated under vacuum. In the case of dithiane and dithiolane derivatives, this afforded the pure carbonyl compound in excellent yield. 

Ylides based upon sulfur are the most generally useful in these cyclopropane-forming reactions.133 Early work in this area was done with the simple dimethyloxysulfonium methylide (9) derived from dimethyl sulfoxide. The even simpler dimethylsulfonium methylide (10) was studied at the same time as a reagent primarily for the conversion of carbonyl compounds into epoxides.134 Somewhat later, other types of sulfur ylides were developed, among which the nitrogen-substituted derivatives such as (11) are... 

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