Aryl halides with alkylamines

The amination of aryl halides and triflates catalyzed by palladium complexes is suitable for use in complex synthetic problems. Many substrates will produce high yields of mixed arylamines with one of the existing catalyst systems. Nevertheless, there are many combinations of substrates for which the amination chemistry may be substantially improved. For the most part, these reactions involve nitrogen centers, such as those in pyrroles, indoles, amides, imidazoles and other heterocyclic groups that are less basic than those in standard alkylamines. Although mild reaction conditions have been developed for many substrates, the harsh conditions used in many of the applications indicate that continued studies on developing mild condi-... 

Phosphines that are tightly chelated to the metal center often achieve high selectivity of secondary over tertiary amine products in reactions of primary alkylamines with unhindered aryl halides. The chelation helps prevent competing /3-hydrogen elimination of the aryl palladium amido intermediate (vide infra). Additionally, the greater steric hindrance of bisphosphine palladium complexes, when compared to mono phosphine palladium complexes, prevents diarylation. Some ligands originally introduced by... 

The reactions of diarylamines with aryl halides is more straightforward than the reaction of secondary alkylamines because these substrates possess no hydrogens on the a carbon and cannot, therefore, nndergo /3-hydrogen elimination as palladium amides. However, competitive formation of arene by an nnknown mechanism remains one side prodnct. For the most part, the synthesis of triarylamines has focused on the preparation of discrete molecules and polymers that are important for electronic materials applications,... 

The reactions of primary arylamines with aryl halides are simpler to catalyze than those of primary alkylamines because /3-hydrogen elimination will not compete with reductive elimination. However, diarylation of the aniline can be a competing process, and for some reason the original catalyst system containing P(o-tolyl)3 showed low activity for the reactions of aniline with aryl halides. 

The heterofunctionalization of haloarenes on a solid support is a versatile method to create smaU-molecule libraries of high diversity. Starting with simple resins, aryl amines can be prepared in good to excellent yield by amination of polymer-bound aryl halides employing either the Hartwig or the Buchwald protocol (BINAP or P(o-Tol)3, t-BuONa (Scheme 16) for a review see Ref. Primary and secondary alkylamines... 

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