synthesis of pyrazole anchored 1, 4-dihydropyridine analogs using pumice-based sulfonic
acid (pumice@ SO 3 H) as a recyclable solid acid catalyst under simple stirring at room
temperature. The present protocol proceeded smoothly with 1, 3-diaryl pyrazole-4-
carbaldehydes, ethyl acetoacetate, and NH 4 OAc in ethanol as a solvent with excellent
yield. The pumice-based sulfonic acid catalyst is easily prepared from naturally occurring …