[Synthesis and properties of the N-ethyl derivatives of carminomycin and rubomycin].

N-Monoethyl derivatives of carminomycin, rubomycin, 13-dihydrocarminomycin and 13-dihydrorubomycin were synthesized by condensation of their amino groups with acetic aldehyde in the presence of sodium boron hydride. The respective N,N-diethyl derivatives of the antibiotics were formed as by-products of the reaction. New compounds such as N-ethylcarminomycin, N,N-diethylcarminomycin, N-ethyl-13-dihydrocarminomycin, N,N-diethyl-13-dihydrocarminomycin, N-ethylrubomycin and N-ethyl-13-dihydrorubomycin were synthesized. Antibacterial activity of N-ethyl- and N,N-diethyl derivatives of carminomycin and rubomycin determined with the use of Bac. mycoides as the test microbe was 40-50 per cent and that of N-ethyl- and N,N-diethyl-13-dihydro-derivatives was 15-30 per cent of the activity of the respective antibiotics, carminomycin and rubomycin.