The ºC) and large amounts of copper reagents

The
aryl amine moiety is frequently found as a key structural element in compounds that
are of biological, pharmaceutical and materials interest. C-N bond-forming
processes are already utilized in the medicinal chemistry and process
development groups of pharmaceutical companies and in academic laboratories.1–3
Metal promoted transformation of aryl halides to various heteroatomic
functional group is an ever-expanding class of reaction in synthetic chemistry.
These reactions provide new route to many compounds of medicinal and industrial
importance.4 Their widespread importance has led to the development
of many synthetic methods for the formation of arylnitrogen bonds.1,5
Amongst them, the classical copper-mediated Ullmann coupling and palladium-catalyzed
aryl coupling are the more commonly used methods.6–13 Classical
copper-mediated aryl coupling reactions have few drawbacks. Most copper (I)
salts are insoluble in organic solvents, and hence, the reactions are often
heterogeneous and require high reaction temperatures (200 ºC) and large amounts
of copper reagents than stoichiometric amounts.14 The reaction is
also very sensitive to the substitution on the aryl halide. Palladium-catalyzed
aryl amine also has some problem of extreme reaction temperatures and high cost
of palladium.15 An important alternative Copper-catalyzed methods has
been reported recently where triarylbismuth16 aryl lead triacetates17
aryl boronic acids18 and hypervalent aryl siloxanes19 are
used as arylating agents instead of aryl halides, the utility of these variants
is limited since the preparation of highly functionalized substrates usually
requires multistep sequences and suffers from high cost, toxicity and limited
scope of the process.

A
recent report also described the solid phase preparation of aryl amines via
displacement of aromatic bromides by various amines in reflux condition.20,21
The synthesis of aryl amines usually need metals for arylation, requires
high temperature22 or functionalizations of any functional group into
more active derivatives (eg., halides, triflates, tosylates, carbamate
derivatives)23 followed by cross coupling reactions. 

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