Chemoselective Reaction of Aaldehydes and 2-Methyl-5-pyrazolone in Different Basic and Acidic Choline chloride-based Deep Eutectic Solvents

Solvents play a key-role for the development of more efficient chemical transformations and industrial processes. A new generation of solvents, named Deep Eutectic Solvents (DESs), was presented as suitable alternative solvents compared to conventional and unconventional solvents, such as ionic liquids (ILs).1,2 Pyrazoles are an important class of bio-active drug targets in the pharmaceutical industry, as they are the core structure of numerous biologically active compounds.3 In this work, the chemoselectivity of the reaction of aromatic aldehydes and 2-methyl-5-pyrazolone, as active methylene compound, for the tandem synthesis of bis(pyrazolyl)methanes 1 and dipyrazolopyrane hybrids 2 in different basic and acidic Choline chloride-based deep eutectic solvents (DESs) has been investigated (Figure 1).

Keywords:

Chemoselectivity , Deep Eutectic Solvents , Pyrazole , Choline chloride/ZnCl2 , Choline chloride/Triflouroacetic acid