Improved synthesis of 1H-pyrazole-4-carbaldehyde

A simple and convenient two-step method for the synthesis of the title compound 1 was developed using N-protected 4-pyrazolilmagnesium bromide 9 as a key intermediate. Laborious procedures for purification or isolation of target compound are not required, therefore, up to 20g of 1 could be obtained in a single run. © 2011 Taylor & Francis Group, LLC.