(R/S) rifamycin derivatives, their preparations and pharmaceutical compositions

1. A compound of structural formula I:

or pharmaceutically acceptable salts of the structural formula I,

wherein:

R 1 is hydrogen or acetyl;

R 2 is hydrogen, or alkyl having from one to six carbon atoms;

wherein asterik (*) denotes the carbon bearing the chiral center, wherein absolute configuration is assigned as R or S.

2. A compound having a formula selected from the group consisting of:

a. (R)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-methylamino}-piperidin-1-ylimino)-methylenyl]-rifamycin SV:

b. (S)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-methylamino}-piperidin-1-ylimino)-methylenyl]-rifamycin SV:

c. (R/S)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-methylamino}-piperidin-1-ylimino)-methylenyl]-rifamycin SV:

d. (R)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-methylamino}-piperidin-1-ylimino)-methylenyl]-rifamycin S:

e. (R)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-methylamino}-piperidin-1-ylimino)-methylenyl]-25-deacetyl-rifamycin SV:

f. (R)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-amino}-piperidin-1-ylimino)-methylenyl]-rifamycin SV:

g. (R)-3-[(4-{1-[1-(3-Carboxy-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-8-yl)-pyrrolidin-3-yl-cyclopropyl]-methylamino}-piperidin-1-ylimino)-methylenyl]-rifamycin SV:

3. A method of preparing a compound of structural formula I:

or pharmaceutically acceptable salts of the structural formula I,

wherein:

R 1 is hydrogen or acetyl;

R 2 is hydrogen, or alkyl having from one to six carbon atoms;

wherein asterik (*) denotes the carbon bearing the chiral center, wherein absolute configuration is assigned as R or S,

comprising:

coupling a hydrazine of formula AF2:

to 3-formylrifamycin of formula 3FRF:

in a solvent at a temperature ranging from about 0° C. to about 50° C.

4. The method of claim 3 , wherein the solvent is water, ethanol, methanol, THF, acetone, acetic acid, or a mixture thereof.

5. The method of claim 3 , further comprising adding an additive selected from the group consisting of sodium hydroxide, ascorbic acid, a salt of ascorbic acid, and sodium acetate.

6. A method of preparing a diaminoacid of formula AF1:

comprising:

reacting a triamine of formula BF1:

with a 4H-4-oxoquinolizine of formula BF2:

in a solvent in the presence of a first base at a temperature ranging from about 20° C. to about 100° C. to produce a compound of formula BF3:

adding a second base in an alcoholic solvent to the compound of formula BF3 to produce a compound of formula BF4:

adding an acid to the compound of formula BF4 to produce the diaminoacid of formula AF 1.

7. The method of claim 6 , wherein the solvent is acetonitrile, the first base is NaHCO 3 , the second base is LiOH, the alcoholic solvent is ethanol, and the acid is trifluoroacetic acid.

8. A method of preparing a protected triamine of formula BF1:

comprising:

reacting 1-benzyl-3-hydroxypyrrolidine with a mesylating agent in the presence of a base and in a first solvent to produce a mesylate;

reacting the mesylate with a cyanide in the presence of a phase transfer catalyst in a second solvent at a temperature ranging from about 20° C. to about 70° C. to produce a cyano compound;

reacting the cyano compound with ethylmagnesium bromide in the presence of titanium tetra-isopropoxide to produce an intermediate cyano compound;

reacting the intermediate cyano compound with a Lewis acid in a third solvent at a temperature ranging from about −78° C. to about room temperature to produce a cyclopropylamine;

reacting the cyclopropylamine with N—BOC 4-piperidone to produce an intermediate aminated cyclopropylamine;

reacting the intermediate animated cyclopropylamine with reductive hydride in a fourth solvent to produce a compound of formula CF1:

reacting the compound of formula CF1 with a palladium catalyst in a fifth solvent to produce the protected triamine.

9. The method of claim 8 , wherein the mesylating agent is mesyl chloride or mesyl anhydride, the base is triethylamine, and the first solvent is toluene or ethyl acetate.

10. The method of claim 8 , wherein the cyanide is tetrabutylammonium cyanide, triethylbenzylammonium cyanide, or mineral cyanide, wherein the phase transfer catalyst is tetrabutylammonium cyanide, and wherein the second solvent is acetonitrile.

11. The method of claim 8 , wherein the Lewis acid is BF 3 etherate and the third solvent is THF, ether, dioxane, or a mixture thereof.

12. The method of claim 8 , wherein the reductive hydride is sodium triacetoxyborohydride and the fourth solvent is THF, dichloromethane, acetic acid, or a mixture thereof.

13. The method of claim 8 , wherein the palladium catalyst is 10% palladium on charcoal or 20% palladium hydroxide, and wherein the fifth solvent is ethanol, methanol, acetic acid, or a mixture thereof.

14. A phamaceutical composition, useful as a medicament for treatment or prevention of bacterial infections, comprising therapeutically effective amount of a compound in accordance with claim 1 in combination with a pharmaceutically acceptable carrier.

15. A method of treating or preventing bacterial infections in a patient comprising administering a pharmaceutical composition as defined in claim 14 .