*Article* **Convenient Access to Functionalized Non-Symmetrical Atropisomeric 4,4***-***-Bipyridines**

**Emmanuel Aubert 1, Emmanuel Wenger 1, Paola Peluso 2,\* and Victor Mamane 3,\***


**Abstract:** Non-symmetrical chiral 4,4--bipyridines have recently found interest in organocatalysis and medicinal chemistry. In this regard, the development of efficient methods for their synthesis is highly desirable. Herein, a series of non-symmetrical atropisomeric polyhalogenated 4,4--bipyridines were prepared and further functionalized by using cross-coupling reactions. The desymmetrization step is based on the *N*-oxidation of one of the two pyridine rings of the 4,4--bipyridine skeleton. The main advantage of this methodology is the possible post-functionalization of the pyridine *N*-oxide, allowing selective introduction of chlorine, bromine or cyano groups in 2- and 2--postions of the chiral atropisomeric 4,4--bipyridines. The crystal packing in the solid state of some newly prepared derivatives was analyzed and revealed the importance of halogen bonds in intermolecular interactions.

**Keywords:** atropisomerism; 4,4--bipyridine; pyridine *N*-oxidation; halogenation; halogen bond; cyanation; Finkelstein reaction; Suzuki coupling
