1-Cyanoacetyl-3,5-dimethylpyrazole

Abstract

1-Cyanoacetyl-3,5-dimethylpyrazole (1) is a white crystalline solid with a melting point of 118–121 °C,[1] stable at room temperature in air. In the 1950s, Ried and Meyer[1] were the first to describe it as a mild cyanoacetylating reagent, being more reactive than ethyl cyanoacetate. Pyrazole 1 is a cheap, handy, and non-toxic reagent that proved to be superior to cyanoacetyl chloride and cyanoacetyl azide in terms of stability and convenience. It is commercially available and can be prepared in about 90% yield by condensation of acetylacetone (2) with cyanoacetohydrazide (3) in aqueous hydrochloric acid (Scheme [1]).[2]