Carbon-nitrogen bond formations

Low concentrations of alkynylamines lead to good yields of cyclic product but high concentrations lead to precipitation of gold and low yields. 

Less than 1 mol% of catalyst is required and the only by-product is water. Au1 and Aum halides were active, with Au111 being slightly more active. 

The use of NaAuCLi (4mol%) as catalyst with the following substituted anilines in ethanol or aqueous ethanol at room temperature gives indoles in good to high yields 29 

---

Azide ion ( N=N=N ) Sodium azide IS a reagent used for carbon-nitrogen bond formation The product IS an alkyl azide... 

Methods for Carbon-Nitrogen Bond Formation Discussed in Earlier Chapters... 

The preparation of amines by the methods described m this section involves the prior synthesis and isolation of some reducible material that has a carbon-nitrogen bond an azide a nitrile a nitro substituted arene or an amide The following section describes a method that combines the two steps of carbon-nitrogen bond formation and reduction into a single operation Like the reduction of amides it offers the possibility of prepar mg primary secondary or tertiary amines by proper choice of starting materials... 

B. Carbon—Carbon and Carbon—Nitrogen Bond Formation. 208... 

Jiang L, Buchwald SL (2004) Palladium-catalyzed aromatic carbon-nitrogen bond formation. In de Meijere A, Diedeiich F (eds) Metal-catalyzed cross-coupling reactions, 2nd edn. Wiley-VCH, Weinheim... 

Transition metal complex-catalyzed carbon-nitrogen bond formations have been developed as fundamentally important reactions. This chapter highlights the allylic amination and its asymmetric version as well as all other possible aminations such as crosscoupling reactions, oxidative addition-/3-elimination, and hydroamination, except for nitrene reactions. This chapter has been organized according to the different types of reactions and references to literature from 1993 to 2004 have been used. 

An important variant for transition metal-catalyzed carbon-nitrogen bond formation is allylic substitution (for reviews, see1,la lh). Nucleophilic attack by an amine on an 7r-allyl intermediate, generated from either an allylic alcohol derivative,2 16,16a 16f an alkenyloxirane,17-19,19a-19d an alkenylaziridine19,19a 19d, or a propargyl alcohol derivative,21,21a 21d gives an allylic amine derivative. 

Carbon-Nitrogen Bond Formation A carbon-nitrogen bond can result either from the reaction between an anodically produced cationic center and an amino group or from the reaction between a nucleophilic center and an electrogenerated electrophilic nitrogen... 

Carbon-Nitrogen Bond Formation The cathodic reduction, in protic media, of aromatic nitro compounds produces nucleophilic centers, either... 

Carbon-Nitrogen Bond Formation Based on Hydrogen Transfer 123 Table 5.9 Transfer hydrogenation of aromatic aldehydes with HCOONa in water. ... 

Carbon-Nitrogen Bond Formation Based on Hydrogen Transfer... 

The cyclizahon of amino alcohols should be an attractive method for the synthesis of N-heterocyclic compounds, mainly because they can be obtained in a single step and without the generation of wasteful byproducts. Carbon-nitrogen bond formation catalyzed by Cp lr complexes has been extended to the synthesis of N-hetero-cyclic compounds by the cyclization of amino alcohols. 

Carbon-nitrogen bond formation, by reductive amination, 59, 1 Carbon-phosphorus bond formation, 36, 2 Carbonyl compounds, addition of... 

The reactions are complex, and ordinarily the first step involves carbon-nitrogen bond formation while the final products are the corresponding hydroxamic acids. 

The kinetic and other evidence obtained suggest that the carbon-nitrogen bond formation is the consequence of a nucleophilic interaction of an Af-phenylchlorohydroxylamine intermediate 135, formed in the second reaction step from 134, and the acyl halide, which leads to an Af-acyl-Af-chlorophenylhydroxylamine cation intermediate 136. The latter loses chlorine with the formation of 137. 

In the case of thiocyanogen chloride and thiocyanogen, the formal electrophile is [NCS]+. The presumed intermediate is a cyanosulfonium ion. The thiocyanate anion is an ambident nucleophile, and both carbon-sulfur and carbon-nitrogen bond formation can be observed, depending upon the reaction conditions (see entry 9 in Scheme 4.5). 

On the other hand, intramolecular carbon—nitrogen bond formation leading to N-substituted-3-acylpyrroles 5 smoothly occurs in 79-96% yield by heating a solution of azadiene 2 having a propargyl appendage at the enamine carbon atom (R3 = CH2—-C C—R5) in toluene or ethanol/... 

Not only acetylene derivatives do undergo palladium catalysed intarmolecular carbon-nitrogen bond formation with amines. The similar reaction of olefins in a Wacker-type process also leads to ring closure. (0-Aminopentenes bearing a suitable leaving group in the 4-position were converted to pyrroles in a cyclization-isomerisation-elimination sequence (3.65.),82... 

In certain cases, when the palladium or nickel catalyzed coupling is not efficient or fails completely, an alternate solution is provided by the use of copper based catalyst systems. The 5-iodouracil derivative shown in 7.77. was unreactive towards imidazole using either the Buchwald-Hartwig conditions or the copper(I) triflate promoted the carbon-nitrogen bond formation reported by Buchwald98 These latter conditions, however, were effective in coupling the iodouracil with a series of other amines (7.77.), The optimal catalyst system consisted of copper(I) triflate, phenantroline and dibenzylideneacetone (dba).99... 

Reactions Leading to Carbon-Nitrogen Bond Formation 1013... 

Dinitrogen complexes of tungsten have been studied in great detail in relation to the function of nitrogenase. They show considerable versatility both with respect to reduction of the coordinated N2 and in reactions leading to carbon-nitrogen bond formation. 

There are two types of interesting and important reactions involving the coordinated dinitrogen, its reduction to hydrazine and ammonia, and the reactions leading to carbon-nitrogen bond formation. 

---