Synthesis and biological evaluation of N-substituted alpha-amino acids from 4-hydroxy coumarins

The synthesis of a series of N-(methylene-4-oxo coumarinyl) carbamates by the condensation of various carbamates with 4-hydroxy coumarins in the presence of triethylorthoformate was undertaken to obtain the the title compounds in 50-55% yields. Preliminary data shows that only few molecules are active against B. subtilis, S. aureus, E. coli and P. aeruginosa at minium inhibitory concentrations (MIC) of 100, 300, 500 micrograms/ml compared to streptomycin (CAS 57-92-1) and kanamycin (CAS 59-01-8). The alkyl groups present in the benzenoid part and the higher amino acid residues like 3a, 3c, 5a and 5b were found to be more active in the title compounds (i.e. 2d and 2e).