Estudo reacional da hidrofosforilação de aldeídos aromáticos e suas propriedades antibacterianas

Abstract

This research aimed to study the low-cost catalyst zinc (II) bis-L-prolinate for Pudovik reactions by involving diverse aldehydes plus the diphenylphosphite. Moreover, this study also aimed the verification of the antibacterial activity of the obtained compounds. We also assessed the catalytic efficiency of the zinc (II) bis-L-prolinate through test in which we changed its reactional time and quantity in various aromatic aldehydes also observing the resulted effects over the reactional yields. Data showed the great efficacy of the catalyst, once the yields seemed to be from good to excellent (57-99%) in a short reactional period (07-10h) with a low amount (30% mol) at room temperature. The reactional mechanism we proposed for the reactions catalyzed by zinc (II) bis-L-prolinate was confirmed through the use of the phosphonate low-acidity di terc-butylphosphonate in the following steps: addition of the nucleophilic structure of the phosphite to the catalyst and the aldehyde addition followed by the addition of the phosphite electron pair to the aldehyde’s carbonyl. Another factor that may confirm the proposed mechanism is that we did not notice any preeminent electronic effect in relation to the group bonded to aldehyde, thus, confirming that the aldehyde addition happened posteriorly to the phosphite addition. With regard to the susceptibility of microorganisms to the Pudovik adducts we performed some diffusion tests with Müeller Hinton agar with the synthetized compounds with benzaldehyde and its correspondent substituents, as well as 4-nitrobenzaldehyde, 4-fluorobenzaldehyde and 3-nitrobenzaldehyde. Preliminary data indicated a significant antimicrobial activity for the compounds synthetized from 4-nitrobenzaldehyde and 4-fluorobenzaldehyde for the Gram positive Staphilococcus aureus bacteria when compared to the antibiotic vancomycin.