Patent ID: 7956183

Claim:
A method for the synthesis of a diaminophenothiazinium compound of the following formula: wherein: each of R 1 and R 9 is independently —H, C 1-4 alkyl, C 2-4 alkenyl, or halogenated C 1-4 alkyl; each of R 3NA and R 3NB is independently —H, C 1-4 alkyl, C 2-4 alkenyl, or halogenated C 1-4 alkyl; each of R 7NA and R 7NB is independently —H, C 1-4 alkyl, C 2-4 alkenyl, or halogenated C 1-4 alkyl; and X is one or more anionic counter ions to achieve electrical neutrality; which method comprises at least the following steps, in order: (a) purifying a corresponding acylated reagent compound of the following formula, wherein R 10 is independently a saturated aliphatic C 1-5 alkyl, phenyl, p-methoxyphenyl, or p-nitrophenyl: (b)(i) deacylating the acylated reagent compound (ARC) to give a corresponding deacylated compound of the following formula: (b)(ii) optionally purifying the deacylated compound; (c)(i) oxidizing the deacylated compound to give the diaminophenothiazinium compound; and (c)(ii) optionally purifying the diaminophenothiazinium compound.