Introduction: Mannich reaction is a typical example of a three-component condensation reaction
and the chemistry of Mannich bases has been the matter of search by researchers. Here, an efficient
procedure for the synthesis of some new Mannich derivatives of simple phenols is described.
Methods: In this procedure, a microwave-assisted and solventless condensation was done between different
phenols, secondary amines and paraformaldehyde. The reactions proceeded in the presence of
the catalytic amount of nano ZnO and tetrabutylammonium bromide (TBAB) in excellent yields. Ten
new compounds were synthesized (A1-A10). Chemical structures of all new compounds were confirmed
by different spectroscopic methods. We optimized the chemical reactions in different conditions. Optimization
reactions were done in the presence of different mineral oxides, different amounts of TBAB
and also different solvents. Nano ZnO and TBAB in catalytic amounts and solvent-free conditions
were the best conditions. All the synthesized compounds were screened for their antimicrobial activities.
Antifungal and antibacterial activities of the synthesized compounds were evaluated against some
Candida species, filaments fungi, gram-positive and gram-negative bacteria by the broth microdilution
method as recommended by CLSI. Results: The result showed that compounds A2, A3 and A4 against
most of the tested Candida species and compounds A5 and A7 against C. parapsilosis and C. tropicalis
exhibited considerable antifungal activities. Moreover, compounds A8 and A10 showed desirable antifungal
activities against C. neoformance and C. parapsilosis, respectively. The antibacterial activities
of the synthesized compounds were also evaluated. Compounds A6 - A10 against E. fecalis and compounds
A5, A7, A9 and A10 against P. aeruginosa showed desirable antibacterial activities. Discussion:
We have synthesized some new Mannich adducts of poly-hydroxyl phenols in the presence of nano-
ZnO as a reusable catalyst, with the hope of discovering new lead compounds serving as potent antimicrobial
agents. The advantages of this method are generality, high yields with short reaction times,
simplicity, low cost and matching with green chemistry protocols. The antimicrobial studies of Mannich
derivatives of phenols showed desirable results in vitro.