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In connection with our studies on antibacterial active compounds in the class of new oxazolidinones against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains, some molecular modifications were attempted. In this study, molecular modifications of 4-aminomethyloxazolidin-2-ones (3a) to the corresponding 4-acylaminomethyloxazolidin-2-one derivatives (3c–d) and preparations of the represented twin-drug type molecules (10–14) were investigated. Some additional 4-dialkylaminomethyloxazolidin-2-ones (2) were also synthesized. The synthesized compounds were evaluated for antibacterial activity with Gram-positive (S. aureus) and Gram-negative (E. coli) strains.

An efficient procedure for the preparation of 5-dialkylaminomethylhydantoins 3, which are easily obtained from cyclization of the corresponding urea derivatives 2 starting with beta-aminoalanines 1, is described. Methylenehydantoin and the corresponding 2-thio analogue (4a, 4b) were obtained from hydantoins 3a and 3b, respectively. Some new chemical properties of these hydantoin derivatives are reported.

Novel benzamide derivatives, N-[1-(aminocarbonyl)-2-(1-piperidinyl)ethyl]benzamides (4 and 5), were prepared from the reaction of beta-piperidinoalanine (6) as the starting material.

An efficient procedure for the preparation of 5-dialkylaminomethylhydantoins 3, which are easily obtained from cyclization of the corresponding urea derivatives 2 starting with beta-aminoalanines 1, is described. Methylenehydantoin and the corresponding 2-thio analogue (4a, 4b) were obtained from hydantoins 3a and 3b, respectively. Some new chemical properties of these hydantoin derivatives are reported.

The preparation of amide derivatives (4) by N-acylation of unprotected alpha-amino acids is easily achieved via readily available benzotriazolyl carboxylates (2a-d) or succinimidyl carboxylates (2e-f). These intermediates (2) are prepared from reaction of carboxylic acids (1) with 1-hydroxybenzotriazole (HO-Bt) or N-hydroxysuccinimide (HO-Su) in the presence of equimolar amounts of 1-ethyl-3-(3'-dimethylaminopropyl)carbodiimide hydrochloride (WSCI). The overall yields of the target compounds (4) were excellent, and this two-stage procedure could be applicable as an alternative procedure for one-pot reaction.

5-Dialkylaminomethylhydantoins (3) were synthesized from β-aminoalanines (1) as the starting materials in two stages. Intermediate urea derivatives (2) prepared from the addition reaction of β-aminoalanines to phenyl isocyanate are easily cyclized to 5-dialkylaminomethylhydantoins (3) with good yields. The deamination reaction of some of the hydantoin derivatives (3a, 3b) in water were observed and resulted in the formation of 3-phenyl-5-methylenehydantoin (4). The hydantoin derivative (3b) regenerated a urea derivative (2c, d) by treatment with excess amounts of pyrrolidine or piperidine.

New oxazolidin-2-ones (3), which mimic the clinically useful antibacterial agent (1) (Linezolid) were prepared by using a cyclization procedure with diethyl carbonate from aminoalcohol (7) starting with DL-serine methyl ester hydrochloride (4) and aromatic carboxylic acid derivatives (5).