Structure of Isometamidium (M. and B. 4180A), 7-m-Amidinophenyldiazoamino-2-amino-10-ethyl-9-phenylphenanthridinium Chloride Hydrochloride, the Red Isomer present in Metamidium

Abstract

THE trypanocidal drug, metamidium, first described by Wragg, Washbourn, Brown and Hill¹, was obtained from the coupling reaction between m-amidinobenzenediazonium chloride and homidium chloride. It was isolated as a mixture of purple and red compounds (55 and 45 per cent, respectively) which were separated by fractional crystallization and shown to be isomeric. The red (M. and B. 4180A) was more active than the purple isomer, both therapeutically and prophylactically, against a laboratory strain of Trypanosoma congolense in mice. Wragg et al. ¹, on the evidence available at the time, provisionally assigned diazoamino structures to these two isomers, and stated that work to verify these was being done. Several unsuccessful attempts were at first made to determine the structure of the red compound, and this has now been achieved by deamination which gave the desamino compound (I), which was identical in analysis, properties, and infra-red spectra with authentic specimens of (I) prepared by : (a) the coupling reaction of diazotized 7-amino-10-ethyl-9-phenylphenanthridinium chloride with m-aminobenzamidine, and (b) the coupling reaction of 7-amino-10-ethyl-9-phenylphenanthridinium chloride with m-amidinobenzenediazonium chloride.