C-N Coupling

Four classes of catalysts have been used for the coupling of amines and related nitrogen nucleophiles witii aryl halides. Initially, complexes of the hindered monodentate aromatic tri-ortlio-tolylphosphine catalyzed the reaction of aryl bromides with secondary amines in the presence of an alkoxide or silylamide base. The use of this catalyst for this type of coupling to form C-N bonds was based on an earlier report of the reaction of aryl bromides with tin amides in the presence of a palladium complex of the same ligand as catalyst. - Later, complexes containing aromatic bisphosphines, such as BINAP and dppf, were 

A selection of ligands that generate catalysts for the coupling of amines with aryl chlorides. 

In many cases, complexes of hindered monodentate alkylphosphines and N-heterocy-clic carbenes are less stable as catalysts for reactions of primary amines than for reactions of secondary amines and are less stable for coupling of halogenated heterocycles, such as pyridines, than they are for coupling of haloarenes. One factor that could lead to this reduced activity is the displacement of the ligand by the primary amine and the basic heterocycle. This point has been debated, but turnover numbers for coupling of these two classes of substrate have tended to be higher for reactions catalyzed by complexes of bisphosphines.  

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Cyanoisopropyl radicals (15) undergo unsymmetrical C-N coupling in preference to C-C coupling.11 1 The preferential formation of the ketenimine is a reflection of the importance of polar and steric influences.1"1 However, the ketenimine is itself thermally unstable and a source of 15, thus the predominant isolated product is often from C-C coupling. 

Preferential C-N coupling is also observed for oligomeric radicals (Scheme 5.9).117 A ketenimine (21) is the major product from the reaction of the "dimeric" MAN radical 18 with cyanoisopropyl radicals (15). Only one of the two possible ketcnimincs was observed a result which is attributed to the thermal lability of ketenimine 19. If this explanation is correct then, although C-N coupling may... 

The presence of two types of catalytic centers (e.g., oxidative and reductive) in the same material can give rise to the possibility of multi-step photocatalysis in a one-pot procedure. C-C coupling, for example, is a field of great interest and a recent very good review was published [221]. C-N coupling reactions are also of interest. 

Blaser, H.-U., Indolese, A.,Naud, F. etal. (2004) Industrial R D on catalytic C—C and C—N coupling reactions apersonal account on goals, approaches and results. Advanced Synthesis and Catalysis, 346 (13-15), 1583-1598. 

Equation 11.44 Solid support aryl/heteroaryl C-N coupling reactions. 

The two-bond HNC dipolar coupling is observable in a 15N-HSQC experiment in which the J coupling between the carbonyl atom C and the 15N amide is active. The doublet components in the 15 N dimension that represent the C N coupling are displaced with respect to one other in the H dimension as in an E.COSY [39] because of this two-bond coupling. 

Campbell and Johnson offered an Sn2 mechanism for the Cu(I)-catalyzed amination of diorganozinc reagents with iV,iV-disubstituted 0-benzoylhydroxylamines, showing that the configuration at the nucleophilic carbon is retained in the C—N coupling . 

A mechanism involving formation of the Af-lithinm derivative of 5h by proton abstraction with higher-order cyanocnprate, followed by C—N coupling of cyano cuprate, was suggested (Scheme 49) ". ... 

In this chapter, C—N couplings, e.g. substitution reactions of carbanions on nitrogen atom of oximes to yield primary amines, have been reviewed. A list of oximes and 0-sulfonyloximes used for electrophilic amination is given in Table 6. These reagents aminate carbanions to A-organylimines as isolable intermediates which are hydrolyzed to primary amines (Scheme 53, path d Scheme 54). Depending on the organometaUic... 

The NMR analysis of N-substituted 11-azaartemisinin analogs 9b was enhanced by additional data acquired by preparing the N-labeled 11-azaartemisinin from artemisinin and NH3 < 1995JME5045>, which showed 7 C-N coupling to C-12 and C-10 and a long range ( 7) coupling to C-9. 

In 2008, Zhao and coworkers have reported a general and highly efficient method for the synthesis of 4-alkyliden-2-azetidinones via copper-catalyzed intramolecular C-N coupling of 3-bromobut-3-enamides [241]. Under Cu(I) catalysis... 

Scheme 5.12 Iron-catalyzed C-N coupling reaction developed by Taillefer et al.

Tetraphenylethylene cyclizes anodically to 9,10-diphenylphenanthrene analogously to its photooxidative cyclization. The attempted anodic cyclization of cis- or frans-stilbene to phenanthrene however failed due to electrophilic reaction of the intermediate radical cation with the solvent 37S Primary aromatic amines are oxidized to radical cations which, depending on the pH of the electrolyte couple to aminodiphenylamines (C-N coupling (84) in Eq. (172) ), yield benzidines (85) at low pH (C-C coupling) or dimerize to hydrazobenzene (86) (N-N coupling) which is subsequently oxidized to azobenzene (Eq. (172) ) 2 5,376,377)... 

Scheme 8.4 Stepwise synthesis of the tetrapeptide 18, containing the sequence 14-17 of the human proinsulin C-peptide, from the methoxy(phenyl)carbene complex 16 via the carbene chromium derivative 17 as the intermediate (Gly-OMe and Pro-OMe were the methyl esters of glycine and proline). The C—N coupling reactions in steps (1)—(4) were carried out using the DCCD/HOSU method, explained in [35]...

The infrared spectrum of l,5-diamino-l,2,4-triazolo[l,5-c]quinazolinium bromide (75) showed two intense absorptions near 1700 cm-1. These absorptions were interpreted, on the basis of deuteration experiments, to be due to v C=N+ coupled with 8 NH2 and other ring modes [79JCS(P2)1708]. 

Calculate the scalar coupling contribution to R] and R2 of the nitrile carbon in acetonitrile, CH313C14N. Take (14N) = 1.8 ms. The C—N coupling constant was measured in the isotopomer CH313C15N, and 1J(13C15N) = —17 Hz. What is the resulting width of the 13C resonance for this carbon ... 

Hartwig has reported a DPPF/Pd-catalyzed C-N coupling reaction between a diarylamine and an aryl nonaflate, Eq. (63) [64bj. The coupling below proceeded in 95 -100% yield (NMR) and was used in a strategy to prepare oligo(m-aniline) compounds. 

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