High purity diaminophenothiazinium compounds including methylthioninium chloride (MTC)

Patent metadata

Field	Value
Publication number	US-9242946-B2
Application number	US-87546510-A
Country	US
Kind code	B2
Filing date	Sep 3, 2010
Priority date	Sep 23, 2004
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

This invention pertains generally to the field of chemical synthesis and purification, and more specifically to methods of synthesizing and purifying certain 3,7 diamino-phenothiazin-5-ium compounds (referred to herein as “diaminophenothiaziniumcompounds”) including Methylhioninium Chloride (MTC) (also known as Methylene Blue). In one embodiment, the method comprises the steps of, in order: nitrosylation (NOS); nitrosyl reduction (NR); thiosulfonic acid formation (TSAF); oxidative coupling (OC); Cr(VI) reduction (CR); isolation and purification of zwitterionic intermediate (IAPOZI); ring closure (RC); chloride salt-formation (CSF); one of: sulphide treatment (ST); dimethyldithiocarbamate treatment (DT); carbonate treatment (CT); ethylenediaminetetraacetic acid treatment (EDTAT); organic extraction (OE); and recrystallisation (RX). The present invention also pertains to the resulting (high purity) compounds, compositions comprising them (e.g., tablets, capsules), and their use in methods of inactivating pathogens, and methods of medical treatment and diagnosis, etc., for example, for tauopathies, Alzheimer's disease (AD), skin cancer, melanoma, viral diseases, bacterial diseases, or protozoal diseases.

First claim

The invention claimed is:

1. A high purity diaminophenothiazinium compound of the following formula:

wherein:
each of R 1 and R 9 is independently selected from: —H; C 1-4 alkyl; C 2-4 alkenyl; and halogenated C 1-4 alkyl;
each of R 3NA and R 3NB is independently selected from: C 1-4 alkyl; C 2-4 alkenyl; and halogenated C 1-4 alkyl;
each of R 7NA and R 7NB is independently selected from: C 1-4 alkyl; C 2-4 alkenyl; and halogenated C 1-4 alkyl; and
X is one or more anionic counter ions to achieve electrical neutrality;

wherein high purity is characterised by a purity of greater than 98% and one or more of the following:
(i) less than 2% Azure B as impurity;
(ii) less than 0.13% Methylene Violet Bernthsen (MVB) as impurity; or
(iii) an elementals purity better than the European Pharmacopoeia (EP) limits of 100 μg/g Aluminium (Al), 10 μg/g Chromium (Cr), 10 μg/g Zinc (Zn), 10 μg/g Copper (Cu), 100 μg/g Iron (Fe), 10 μg/g Manganese (Mn), 10 μg/g Nickel (Ni), 10 μg/g Molybdenum (Mo), 1 μg/g Cadmium (Cd), 1 μg/g Tin (Sn), and 10 μg/g Lead (Pb).

2. A high purity diaminophenothiazinium compound according to claim 1 , obtained by a method of synthesis comprising the steps of:
(a) oxidative coupling, in which a thiosulfuric acid S—{2-(amino)-3-(optionally substituted)-5-(disubstituted amino)-phenyl} ester, 4, is oxidatively coupled to an N,N-disubstituted-3-optionally substituted-aniline, 5, using an oxidizing agent that is or comprises Cr(VI), to give a [4-{2-(thiosulfate)-4-(disubstituted amino)-6-(optionally substituted)-phenyl-imino}-3-(optionally substituted)-cyclohexa-2,5-dienylidene]-N,N-disubstituted ammonium, 6:

(b) isolation and purification of zwitterionic intermediate, in which said [4-{2-(thiosulfate)-4-(disubstituted amino)-6-(optionally substituted)-phenyl -imino}-3-(optionally substituted)-cyclohexa-2,5-dienylidene]-N,N-disubstituted ammonium, 6, is isolated and purified;
(c) ring closure, in which said isolated and purified [4-{2-(thiosulfate)-4-(disubstituted amino)-6-(optionally substituted)-phenyl-imino}-3-(optionally substituted)-cyclohexa-2,5-dienylidene]-N,N-disubstituted ammonium, 6, is subjected to ring closure to give a 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium salt, 7:

(d) chloride salt formation, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium salt, 7, is reacted with chloride, to give a 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8:

(e) sulphide treatment, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8, is treated with a sulphide; and
(f) organic extraction, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8, in aqueous solution or suspension, is treated with dichloromethane.

3. A high purity diaminophenothiazinium compound according to claim 2 , wherein:
said oxidizing agent for said oxidative coupling step is Na 2 Cr 2 O 7 ;
said oxidative coupling step is performed under acidic conditions;
said ring closure step is achieved by treatment with Cu(II) sulfate; and
said ring closure step is performed under acidic conditions.

4. A high purity diaminophenothiazinium compound according to claim 2 , which is obtained by a method of synthesis comprising the steps of:
(a) nitrosylation, in which an N,N-disubstituted-3-optionally substituted aniline, 1, is 4-nitrosylated to give said N,N-disubstituted-3-optionally substituted-4-nitrosyl aniline, 2:

(b) nitrosyl reduction, in which an N,N-disubstituted-3-optionally substituted-4-nitrosyl aniline, 2, is reduced to form said N,N-disubstituted-1,4-diamino-5-optionally substituted benzene, 3:

(c) thiosulfonic acid formation, in which an N,N-disubstituted-1,4-diamino-5-optionally substituted benzene, 3, is oxidized in the presence of a thiosulfate to give said thiosulfuric acid S-{2-(amino)-3-(optionally substituted)-5-(disubstituted-amino)-phenyl} ester, 4:

(d) oxidative coupling, in which a thiosulfuric acid S-{2-(amino)-3-(optionally substituted)-5-(disubstituted amino)-phenyl} ester, 4, is oxidatively coupled to an N,N-disubstituted-3-optionally substituted-aniline, 5, using an oxidizing agent that is or comprises Cr(VI), to give a [4-{2-(thiosulfate)-4-(disubstituted amino)-6-(optionally substituted)-phenyl-imino}-3-(optionally substituted)-cyclohexa-2,5-dienylidene]-N,N-disubstituted ammonium, 6:

(e) Cr(VI) Reduction, in which the product of the oxidative coupling step is treated to convert residual Cr(VI) to Cr(III);
(f) isolation and purification of zwitterionic intermediate, in which said [4-{2-(thiosulfate)-4-(disubstituted amino)-6-(optionally substituted)-phenyl-imino}-3-(optionally substituted)-cyclohexa-2,5-dienylidene]-N,N-disubstituted ammonium, 6, is isolated and purified;
(g) ring closure, in which said isolated and purified [4-{2-(thiosulfate)-4-(disubstituted amino)-6-(optionally substituted)-phenyl-imino}-3-(optionally substituted)-cyclohexa-2,5-dienylidene]-N,N-disubstituted ammonium, 6, is subjected to ring closure to give a 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium salt, 7:

(h) chloride salt formation, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium salt, 7, is reacted with chloride, to give a 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8:

(i) sulphide treatment, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8, is treated with a sulphide;
(j) organic extraction, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8, in aqueous solution or suspension, is treated with dichloromethane; and
(k) recrystallisation, in which said 3,7-bis(disubstituted-amino)-1,9-(optionally substituted)-phenothiazin-5-ium chloride salt, 8, is recrystallised.

5. A high purity diaminophenothiazinium compound according to claim 3 , which is obtained by a method of synthesis comprising the steps of:
(a) nitrosylation, in which an N,N-disubstituted-3-optionally substituted aniline, 1, is 4-nitrosylated to give said N,N-disubstituted-3-optionally substituted-4-nitrosyl aniline, 2:

(b) nitrosyl reduction, in which an N,N-disubstituted-3-optionally substituted-4-nitrosyl aniline, 2, is reduced to form said N,N-disubstituted-1,4-diamino-5-optionally substituted benzene, 3:

Assignees

• Storey John Mervyn David
• Sinclair James Peter
• Marshall Colin
• Tan Han Wan
• Wischik Claude Michel
• Wista Lab Ltd

Inventors

• Storey John Mervyn David
• Sinclair James Peter
• Marshall Colin
• Tan Han Wan
• Wischik Claude Michel

Classifications

• A61P31/14

  for RNA viruses · CPC title

• A61P33/02

  Antiprotozoals, e.g. for leishmaniasis, trichomoniasis, toxoplasmosis · CPC title

• A61P35/00

  Antineoplastic agents · CPC title

• A61P31/18

  for HIV · CPC title

• A61P31/04

  Antibacterial agents · CPC title