B 663 is one of a large series of rimino-compounels of structure 1 synthesizeel originalIy in these laboratories as potential antimycobacterial agents. These are orange-reel phenazine eleriva tives whose colour is relateel to their quinone imine character. In B 663, R" represents 'CH(CHa) 2 anel R' anel R'" are 'C6H4CI(p) resielues. The synthesis anel chemistry of these compounels have been elescribeel by Barry anel co-workers in a series of papers (