Abstract The extent of intramolecular cyclization in a series of Mannich bases derived from 2- arylidene-1, 3-diketones (series 5) was probably influenced by the steric and electronic properties of the different basic groups. Replacement of one of the keto groups in series 5 by hydrogen, methyl, carboethoxy and phenyl functions gave series 6 in which the intramolecular cyclization process was abolished. Evaluation of the compounds versus ...