Single coupling reactions with amines

We have noticed a correlation between the logarithm of the selfexchange rate constant for a series of [CoNe] couples and the degree of substitution at the coordinated amines as judged by the number of amine protons in the complex (Fig. 12). It should be noted that more than half the points that fall on the line have been estimated by application of the cross relationship to the rate of a single cross reaction with (102). Not all the points in the plot are homoleptic complexes some mixed ligand CoNe complexes were included because of the need to try to verify the unexpected observation. The line in Fig. 12 was... 

Azo Coupling. The coupling reaction between an aromatic diazo compound and a coupling component is the single most important synthetic route to azo dyes. Of the total dyes manufactured, about 60% are produced by this reaction. Other methods iaclude oxidative coupling, reaction of aryUiydraziae with quiaones, and oxidation of aromatic amines. These methods, however, have limited iadustrial appHcations. 

The same type of modification with carboxylate molecules can be done in aqueous solution using EDC. If the ligand to be coupled only has a single carboxylate with no amines or other nucleophiles present, then the dendrimer and ligand may be dissolved at a similar molar ratio in aqueous buffer and EDC added to facilitate the coupling reaction. 

Lam and coworkers292 and Antilla and Buchwald297 expanded the scope of this type of catalytic coupling to encompass reactions of amines. Lam reported the coupling of aliphatic and aromatic amines, as well as heterocycles with N—H bonds with a combination of Cu(OAc)2 (10 mol%) and co-oxidants like pyridine A-oxide (PNO) or TEMPO in air. No single set of conditions led to coupling of all substrates. Concurrently, Buchwald reported reactions at room temperature catalyzed by Cu(OAc)2 (5-10 mol%) and myristic acid with stoichiometric amounts of 2,6-lutidine as base. Substituted anilines, as well as primary and secondary amines, reacted with a series of arylboronic acids. Excellent yields of arylated products were obtained for reactions of anilines, but only moderate yields were obtained for reactions of aliphatic amines. Yudin and coworkers employed this protocol to prepare A-aryl aziridines (equation 72)298. 

Topics reviewed during the year include the photochemistry of indoles, sulfoxides, pyrazoles and isothiazoles, (S-hetero)cyclic unsaturated carbonyl compounds, photoinduced single electron transfer (SET) reactions of amines and of azo compounds, SET reactions of organosilanes and organostannanes with Qo and ketones, photochromic polypeptides and di(hetero)arylethenes, processes in chromophore sequences on a-helical polypeptides,aryl-aryl coupling in furans, thiophenes and pyrroles," [3+2]cycloaddition of aromatic nitriles (and esters) with alkenes, and reactions of benzylsilane derivatives. ... 

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