A simple new hydrazine-free synthesis of methyl 1,4,5-trisubstituted 1H-pyrazole-3-carboxylates
作者:Břetislav Brož、Zdeňka Padělková、Valerio Bertolasi、Petr Šimůnek
DOI:10.1007/s00706-013-0962-2
日期:2013.7
Conditions for successful syntheses of polysubstituted pyrazole-3-carboxylates have been found. The methodology consists in mixing equimolar amounts of diazonium tetrafluoroborates and enaminoesters in presence of sodium acetate. 1-Methylpyrrolidone has appeared to be the solvent of choice. The compounds prepared have been characterized by means of nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and in two cases, also by X-ray diffraction. The advantage of the methodology is a simple implementation without necessity of working under inert atmosphere. The presence of other functional groups enables further synthetic transformations of the products.