Rifamycin antibiotics—new compounds and synthetic methods. Part 1: Study of the reaction of 3-formylrifamycin SV with primary alkylamines or ammonia

Within the study covering the search for new methods of synthesis of rifamycin antibiotics, the reactions of 3-formylrifamycin SV () with primary amines or ammonia were studied. In the reaction of with methylamine, unstable 3-methyliminomethylrifamycin SV () was formed, which was further oxidised to stable 3-methyliminomethylrifamycin S (). In the reaction of with ammonia, N,15-didehydro-15-deoxo-pyrimido-(4,5-b)rifamycin SV (), a new compound with a chromophore system enlarged by a pyrimidine ring, was obtained. The product of its reduction with sodium borohydride—()—was also isolated. The structures of the compounds and an explanation of the synthesis mechanism have been proposed on the basis of mass spectrometry results as well as (1D) and (2D) 1H- and 13C NMR analysis. In vitro antituberculous activity of the new compounds have been investigated.