Abstract
Efficient chemical pathways leading to differently substituted 3-aminopyridazines have been reviewed with the general objective to help to design the most straightforward chemical pathways to produce libraries of compounds with largest chemical diversity. Thus 3-chloropyridazines bearing at different positions halogens may offer opportunities, when submitted two tandem of selected reactions leading to the expected compounds (amination vs. palladium cross coupling reactions (PCCR)). As a result of its electron-deficient system, the commercially available 3,6-dichloropyridazine offers a large panel of reactivities in particular the access to 4-functionalized systems (vicarious nucleophilic substitution, halogenation, metalation/alkylation, arylation using Lewis acid catalyst). In other cases, the functionalized pyridazin-3- one precursors may be helpful as the free amide could also deal with PCCR by means of its O-Triflate derivative. A particular attention was given to opportunities offered by electron deficient 3,6, 3,4,6, 3,4,5, and 3,4,5,6- polychloropyridazines. However increasing the number of chlorines increased the number of possible combinations toward both amination and PCCR, and in general, led to a loss of regioselectivity. Thus introduction of different functionalities (bromine, iodine, enol, nitro, cyano, methyl and other carbon acids) at the pyridazine ring significantly increased their potentials, (increased reactivity and regioselectivity). Finally tetra-functionalized pyridazines were briefly introduced. They may constitute the most suitable scaffolds for building in an expeditive manner different 3- aminopyridazine sub-series by means of combinatorial chemistry.
Keywords: Sonogashira reaction, Diels-Alder reactions, vicarious nucleophilic substitution, benzodiazepine receptor, Anti-angiogenic, pyridazine drugs
Call for Papers in Thematic Issues
Catalytic C-H bond activation as a tool for functionalization of heterocycles
The major topic is the functionalization of heterocycles through catalyzed C-H bond activation. The strategies based on C-H activation not only provide straightforward formation of C-C or C-X bonds but, more importantly, allow for the avoidance of pre-functionalization of one or two of the cross-coupling partners. The beneficial impact of ...read more
Related Books
Advances in Organic Synthesis
The Synthetic Methods, Structures, and Properties of the Ca-C σ Bond Organocalcium Containing Compounds
Advances in Organic Synthesis
Chemistry of Bipyrazoles: Synthesis and Applications
Advances in Organic Synthesis
Advanced Nanocatalysis for Organic Synthesis and Electroanalysis
Advances in Organic Synthesis
Advances in Organic Synthesis
6