Recent Advances in the Synthesis of 2,2′-Bipyridines and Their Derivatives

Abstract

The sustained interest in the synthesis of new analogues of 2,2′-bipyridines is supported by the importance of compounds featuring bipyridine core in diverse areas of chemical, biomedical and materials research, which is relayed into the development of new approaches and the expansion of existing synthetic methods. This short review covers advances in the synthesis of 2,2′-bipyridines, including both the synthesis of compounds with a given substitution pattern and the development of new methods for assembling the bipyridine core. Special attention is directed toward the use of pyridine N-oxides and metal-free protocols to facilitate the formation of bipyridines. This short review focuses primarily on reports published in the last 5–6 years.1 Introduction2 Ullmann-Type Homocoupling Reactions3 Cross-Coupling Reactions in the Synthesis of Bipyridines4 Coupling Reactions Employing Pyridine N-Oxides5 Other Methods for the Synthesis of 2,2′-Bipyridines6 Conclusions and Outlook

Efficient emission of Zn(ii) and Cd(ii) complexes with nopinane-annelated 4,5-diazafluorene and 4,5-diazafluoren-9-one ligands: how slight structural modification alters fluorescence mechanism

“…2,2′-Bipyridine ( bipy ) has become one of the most recognizable and commonly used bidentate N , N -chelating ligands in coordination chemistry since its discovery by Fritz Blau in 1888. 1–14 Pioneering works on coordination compounds with bipy provided chemists with first insights into the thermodynamics and kinetics of metal ion complexation, metal–ligand bonding properties, and photo-, magneto-, and electrochemistry of metal complexes. Over two centuries, all these studies have played a pivotal role in the development of our modern understanding of the fundamental aspects of coordination chemistry.…”

De Novo Synthesis of 2,2′-Bipyridines and Related Bis-azines via Cascade Coupling and Double Pyridannulation of Isocyanides

“…Another strategy for the synthesis of 2,2′-bipyridines is based on the creation of one of the two pyridine rings by cyclization reactions, such as Kröhnke cyclization, [2 + 2 + 2], [4 + 2], and rearrangement (Scheme b). Although great progress has been made in this area, − these methods predominantly rely on the coupling or cyclization of specific pyridine derivatives, wherein the products are often provided with restricted substitution pattens. Therefore, the development of an efficient and more flexible method that features the simultaneous formation of two pyridine rings in a single operation remains highly desirable.…”

“…Bipyridines, 2-(2-pyridyl)-quinolines, 2-(2-pyridyl)-quinoxalines, and related bis-azines represent a ubiquitous and significant class of N -containing biheteroaryls (Figure ). In this regard, 2,2′-bipyridines are one of the most representative examples of biheterocycles that draw considerable attention in the research areas of catalysis, coordination chemistry, supramolecular chemistry, and photochemistry. , Since its synthesis by distillation of copper­(II) pyridine-2-carboxylate in 1888, numerous protocols toward 2,2′-bipyridines have been continually disclosed . One of the most widely used approaches is construction of the heterobiaryl C–C bond by transition-metal-catalyzed homo- or cross-coupling of preformed pyridine derivatives (Scheme a, top). , The couplings of sulfur/phosphine-mediated pyridine salts are viable alternatives for the aforementioned metal-catalyzed reactions (Scheme a, bottom) .…”

“… In this regard, 2,2′-bipyridines are one of the most representative examples of biheterocycles that draw considerable attention in the research areas of catalysis, coordination chemistry, supramolecular chemistry, and photochemistry. , Since its synthesis by distillation of copper­(II) pyridine-2-carboxylate in 1888, numerous protocols toward 2,2′-bipyridines have been continually disclosed . One of the most widely used approaches is construction of the heterobiaryl C–C bond by transition-metal-catalyzed homo- or cross-coupling of preformed pyridine derivatives (Scheme a, top). , The couplings of sulfur/phosphine-mediated pyridine salts are viable alternatives for the aforementioned metal-catalyzed reactions (Scheme a, bottom) . Another strategy for the synthesis of 2,2′-bipyridines is based on the creation of one of the two pyridine rings by cyclization reactions, such as Kröhnke cyclization, [2 + 2 + 2], [4 + 2], and rearrangement (Scheme b).…”