TBD-Organocatalysed Synthesis of Pyrazolines

TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene) catalyzes the synthesis of 3,5-diarylpyrazolines from chalcones and acylhydrazines. TBD promotes the cyclocondensations via the regioselective secondary amine alkylation of acylhydrazines, while the other amine bases, DBU, DMAP and etc., promote the aza-Michael reactions via primary amine addition of these reagents.