Gas-phase synthesis of pyrazolo[3,4- b ]pyridin-4-ones

Abstract

Flash vacuum pyrolysis (FVP) at 500-600 °C of 1-substituted pyrazolylaminomethylene derivatives of Meldrum's acid provides 1-substituted pyrazolo[3,4-b]pyridin-4-ones in high yields. If the 1-substituent is a tert-butyl group, FVP at 750-850 °C causes elimination of 2-methyl-1-propene to give the parent pyrazolo[3,4-b]pyridin-4-one.