Reviews and Accounts ARKIVOC 2012 (i) 491-545 Page 491 © ARKAT-USA, Inc Synthesis and applications of bipyrazole systems Bakr F. Abdel-Wahab a and Kamal M. Dawood b* a Applied Organic Chemistry Department, National Research Centre, Dokki, Giza, Egypt b Chemistry Department, Faculty of Science, Cairo University, Giza 12613, Egypt E-mail: dr - dawood@yahoo.com Abstract This review focuses on the synthetic methodologies towards ten main classes of bipyrazole systems (according to the type of connection between them): 1,1'-, 1,3'-, 1,4'-, 1,5'-, 3,3'-, 3,4'-, 3,5'-, 4,4'-, 4,5'- and 5,5'-junctions. The research and industrial applications of these bipyrazoles are reported as well. Keywords: Pyrazoles, bipyrazoles, synthesis, cycloaddition, heterocycles Table of Contents 1. Introduction 2. Synthesis and Reactions of Bipyrazoles 2.1. 1,1'-Bipyrazoles 2.2. 1,3'-Bipyrazoles 2.3. 1,4'-Bipyrazoles 2.4. 1,5'-Bipyrazoles 2.5. 3,3'-Bipyrazoles 2.6. 3,4'-Bipyrazoles 2.7. 3,5'-Bipyrazoles 2.8. 4,4'-Bipyrazoles 2.9. 4,5'-Bipyrazoles 2.10. 5,5'-Bipyrazoles 3. Applications of Bipyrazoles 4. References 1. Introduction Three main types of connections between two pyrazole moieties can be considered; N,N-, C,N-, and C,C-linked bipyrazoles. According to numbering there are pertinent ten systems of bipyrazole which differ in the position of the bond between the two pyrazole rings as shown in Figure 1.