Abstract
Pyrazole, a member of the structural class of azoles, exhibits molecular properties of interest in pharmaceuticals and materials chemistry, owing to the two adjacent nitrogen atoms in the five-membered ring system. The weakly basic nitrogen atoms of deprotonated pyrazoles have been applied in coordination chemistry, particularly to access coordination polymers and metal-organic frameworks, and homocoupling reactions can in principle provide facile access to bipyrazole ligands. In this context, we summarize recent advances in homocoupling reactions of pyrazoles and other types of azoles (imidazoles, triazoles and tetrazoles) to highlight the utility of homocoupling reactions in synthesizing symmetric bi-heteroaryl systems compared with traditional synthesis. Metal-free reactions and transition-metal catalyzed homocoupling reactions are discussed with reaction mechanisms in detail.
Highlights
Heterocyclic compounds containing two or more nitrogen atoms display unique molecular properties, which can be extended to macroscale properties in materials chemistry [1]
The utility of bipyrazole materials in materials chemistry is discussed in Section 3.3, where we provide ample information on constructing metal–organic frameworks based on bipyrazole ligands
1,1,2,2-ethanetetracarbaldeyde, which was converted to bipyrazole by a condensation reaction with bipyrazoles via lengthy synthetic steps starting from diethyl succinate via a 3,4-carbonyl furan hydrazine (Scheme 1C) [9]
Summary
Heterocyclic compounds containing two or more nitrogen atoms display unique molecular properties, which can be extended to macroscale properties in materials chemistry [1]. Symmetric, multiply-functionalized organic ligands are required to construct ordered materials, preferably in high crystallinity [2]. Ullmann coupling reactions can enable facile access to symmetric biaryl compounds using copper reagents with or without ligands at high reaction temperatures [4,5]. Based on this method, a plethora of reports was dedicated to the homocoupling of aromatic compounds, accessing symmetric molecules starting from simple aryl halides and derivatives. Milder and more practical reaction conditions are required To this end, this review summarizes recent development in (catalytic)homocoupling reactions of.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
