[3+2] Cycloaddition of Aryl Diazo Ketones: An Access to Bioactive 4-Hydroxy Pyrazoles

Abstract

We designed a novel and straightforward route for constructing 4-hydroxypyrazole frameworks via a Lewis acid mediated [3+2] cycloaddition of aryl diazoketones. Pyrazoles are very useful heterocycles and the pyrazole framework is usually found in various biologically active scaffolds and it’s been used as the important core in building different useful compounds as well. The aim of the thesis is to synthesize the hydroxy pyarzoles under mild and transition-metal free conditions using commercially viable reagents. In this regard, we have synthesized diazo carbonyl compounds and they were subjected for the screening with a few Lewis acids. Gratifyingly, tert-butyldimethylsilyl Trifluoromethanesulfonate (TBSOTf) proved to be efficient for the cyclization of the diazo ketone to afford the corresponding the hydroxy Pyrazoles.