Synthesis and in vitro antifungal activity against Fusarium oxysporum of N-alkyl-substituted amides derived from 2-amino acids

N-alkyl substituted amides 1-16 were synthesized from diethyl malonate and alkyl esters derived from the amino acids L-tryptophan, L-alanine, L-phenylalanine, and L-tyrosine. In addition, a microwave-assisted protocol was employed using a Lewis acid (AlCl3) or dimethylaminopyridine (DMAP) as a catalyst and nucleophilic auxiliary, respectively, afFording the desired compounds. The results suggest that DMAP-catalyzed reactions under microwave irradiation yield higher during short reaction times. Each reaction method's mechanistic proposals for forming N-alkyl-substituted amides are presented to illustrate the observed difFerences. The synthesized amides were evaluated under in vitro conditions against Fusarium oxysporum. The compounds exhibited antifungal activity at difFerent levels (0.40 mM < IC50 < 29.1 mM). These results indicated that the observed activity variations of this compound group might be due to the efFect of acyclic amide as a non-classical bioisostere of some heterocyclic phytoalexins.