Process for synthesizing triarylmethane sulfone compounds

A process for synthesizing a compound corresponding to formula (I), the process comprising:

• (a) condensing a benzaldehyde compound of formula (II) with dialkylaniline of formula (III) to give a triphenylmethane of formula (IV)
• R3, R4, and R5 being as defined for formula (I);
• (b) treating the triphenylmethane of formula (IV) with sulfuric acid to form a triphenylmethane sulfone of formula (V)
• R1, R2, R3, R4, and R5 being as defined for formula (I);
• and
• (c) oxidizing the triphenylmethane sulfone of the formula (V) with a quinone to obtain the compound of formula (I)
• wherein
• R1 and R2 are independently —SO3H or —SO3−,
• R3 is —OH, —OR′, or —OCOOR′, where R′ is a C1-C8 alkyl, a C2-C8 alkenyl, a phenyl, or a benzyl,
• R4 and R5 are independently a C1-C8 alkyl, a C2-C8 alkenyl, a phenyl, or a benzyl, wherein two groups R4 and R5 borne by the same nitrogen atom optionally together form a ring including the nitrogen atom,
• Y is an organic or inorganic cation which is pharmaceutically acceptable salt, and
• t is 0, ½, or 1.