GB2159518A - New anthracyclines and process for manufacture - Google Patents

Abstract

A new class of antitumoral anthracyclines glycosides of the general formula I and II: <IMAGE> wherein R<1> = H, OCH3 and R<2> is H, OH, is described. The used starting material is 4'-epi-daunorubicin or its 4-demethoxy analogue, which, after protection of the amino group on the sugar moiety as benzophenone Schiff base, are reacted with trifluoromethanesulfonic anhydride to obtain the corresponding 4'-epi-4'-O-trifluoromethanesulfonates from which, after treatment with n-tetrabutyl ammonium fluoride and a subsequent mild acidic hydrolysis of the N-protecting group, the daunorubicin derivatives of formula I and II are obtained as a mixture of free bases. A chromatography on a column of buffered silica gel allows the separation of the compounds I and II which are finally isolated at their hydrochlorides and transformed, in case, into their doxorubicin analogues via their 14-bromo derivatives and subsequent hydrolysis with aqueous sodium formate.

Description

SPECIFICATION New anthracyclines and process for manufacture The present invention relates to anthracycline glycoside derivatives, to their preparation and to pharmaceutical compositions containing them as well as to intermediates useful in the preparation of the glycosides.

The present invention provides anthracycline glycosides having the general formula I or II

wherein Rq represents an hydrogen atom or a methoxy group and R2 represents an hydrogen atom or an hydroxy group and pharmaceutically acceptable acid addition salts thereof.

Suitable acid addition salts include salts of the mineral acids such as hydrohalic acids, especially hydrochloric acid as well as salts of organic carboxylic and sulphonic acids especially acetic acid.

The present invention thus provides daunorubicin and doxorubicin analogs bearing a fluorine atom in the sugar moiety; more particularly the C-7 OH of the natural anthracyclinones, daunomycinone and adriamycinone, and the totally synthetic 4-demethoxydaunomycinone and 4-demethoxy-adriamycinone is glycosidically linked to the new sugars 2, 3,4,6-tetradeoxy-3-amino-4-fluoro-L-arabinohexopyranose Ill and 2,3,5,6-tetradeoxy-3-amino-5-fluoro-L-arabinohexo- furanose or 2,3,5,6-tetradeoxy-3-am ino-5-fluoro-D xylohexo- furanose IV. The above mentioned nomenclatures for the sugar IV derive from the uncertainty concerning the absolute configuration of the fluorine bearing carbon atom.

The present invention also provides the intermediates Ill and IV and compounds 2 to 7 shown in the Reaction Scheme useful for the preparation of compounds of general formulas I and II. The present invention further provides a process for producing a compound of Formula (1) or (II) which process comprises protecting the amino group of a compound of Formula (V)

wherein R1 is as defined in relation to Formulae I and II converting the 4'-hydroxy group into a fluoro substituent, removing the amino protecting group and, if required converting the 14-methyl group into a hydroxy methyl group, and optionally thereafter forming a pharmaceutically acceptable acid addition salt.

The process of the invention are summarized in the following Reaction Scheme: Reaction Scheme

The starting materials for the preparation of the new anthracyclines 6-9 a,b are: 4'-epidaunorubicin (1a) [see F. Arcamone et al., J. Med Chem. 18, 703 (1975)] and 4-demethoxy-4'!epidaunorubicin (ib) [see A. Di Marco et al., Cancer Treat. Rep. 62, 375 (1978)].

In order to form the fluoro derivatives, the amino group on the sugar moiety is protected as a benzophenone Schiff base 2a,b, then treatment with trifluoromethane- sulfonic anhydrode in anhydrous methylene dichloride and in the presence of an organic base such as dry pyridine gives the corresponding 4' epi-4'-O-trifluoromethanesulfonate 3a,b in almost quantitative yield.

Reaction of 3a,b with a fluoride salt in an aprotic solvent gives a mixture of products 4-5a,b.

Mild acidic hydrolysis of the N-diphenylmethylene protecting group yields the new daunorubicin deriv atives 6-7a,b which are separated by chromatography.

The conversion of 6-7a,b to the corresponding doxo anaiogs 8-9a,b is performed as described in US Patent 3,803,124 for the conversion of daunorubicin to doxorubicin via the 14-bromo-derivative The gly cosides 6a (Ra = OCH3), 6b (Ra = H), 7a (R1 = OCH3), 7b (RI = H) and the corresponding doxo derivatives: 8a (R' = OCH3), 8b (R1 = H), 9a (R' = OCH3) and 9b (RI = H) are useful as antitumor agents.

The invention further provides a pharmaceutical composition comprising an anthracyclic glycosides of the general formula I or II or a pharmaceutically acceptable acid addition salt thereof as active ingredient together with a pharmaceutically acceptable carrier therefor.

The compositions may be formulated in conventional manner using conventional carriers.

The compounds of formulae (I) and (II) may be administered in therapeutically effective amounts by conventional routes and in conventional dosage regimes such as those used for daunorubicin and doxo rubicin.

The compounds of formulae (I) are useful in methods of treatment of the human or animal body by therapy. In particular the compounds of formulae (I) and (II) are useful as antitumor agents.

The following Examples illustrate the invention.

EXAMPLE 1 Preparation of 4'-epi-N-(diphenylmethylene)-daunorubicin (2a) A solution of 2 g of 4-epidaunorubicin (1a) in 80 ml of dichloromethane was treated with 1 g of benzo phenone imine at 35"C. After four hours the solvent was removed in vacuum and the residue was first triturated with hexane to eliminate the traces of benzophenone imine then crystallized from diethyl ether hexane to give 2a m.p. 190-195 C - FD-MS 691 (M+) Ref 0.35 on TLC Kieselgel F 254 (Merck) using as eluent the solvent mixture dichloromethane/acetone (8/2 v/v).

; EXAMPLE 2 Preparation of 4'-epi-4'-0-trifluoromethanesulfonate-N- (diphenylrnethylene)-daunorubicin (3a) To a solution of 2 g of 4'-epi-N-(diphenylmethylene)-dauno- rubicin (2a) in 40 ml of anhydrous dichlo romethane and 0.3 ml of dry pyridine kept at -10 C under nitrogen, was added a solution of 0.6 ml of trifluoromethanesulfonic anhydride in 10 ml of anhydrous dichloromethane. After 30 minutes the reaction mixture was diluted with dichloromethane and washed with water, cold 0.1 N HCI, cold aqueous 5% NaHCO3 and water.

The organic phase, dried over anhydrous sodium sulphate, was filtered off and the solvent removed in vacuum to give 3a. Rf 0.6 on TLC Kieselgel F 254 (Merck) using as eluent the solvent mixture dichlorome thane/acetone (95/5 v/v).

i PMR (200 M Hz, CDCI3): 1.39 (d, J=6.2 Hz, 3H, CH3), 1.79 (dd, J=5 3, 13.6 Hz, 1H, H2' eq), 2.07-2.2 (m, 1H, H2' ax), 2.34 (s, 3H, COCH3), 3.86 (ddd, J=5 3, 9.5, 12,0 Hz, 1H, H-3'), 3.96 (dq, J=6 2, 9.5 Hz, 1H, H-5'), 4.07 (s, 3H, OCH3), 4.97 (dd, J=9.5, 9.5 Hz, 1H, H-4'), 5.26 (dd, J=2.4, 3.6 Hz, 1H, H-7), 5.46 (dd, J= < 1, 3.5 Hz, 1H, H-1'), 7 00-7.63 (m, 10H, (Ph)2C=N) EXAMPLE 3 Preparation of 2', 3',4',6'-tetradeoxy-3'iamino-4'- fluoro-L-arabino-hexopyranosyl-daunorubicin (6a) and 2',3',5',6'-tetradeoxy-3'-amino-5'-fluoro-hexofuranosyl- daunorubicin (7a) To 1.5 g of 4'-epi-4'-O-trifluoromethanesulfonate-N- (diphenylmethylene)-daunorubicin (3a) dissolved in 8 ml of an hydros dichloromethane, was added a solution of anhydrous n-tetra-butylammonium fluoride (2 g) in 8 ml of anhydrous acetonitrile. The reaction mixture was kept at 0 C with stirring under nitrogen for 24 hours, then was poured into 500 ml of ethyl acetate. The organic phase was washed with water, dried over anhydrous sodium sulphate, filtered off and the solvent was removed in vacuum.

The crude mixture, containing 4a and 5a was treated with 0.1 N HCI in methanol for 1 hour at room temperature, then was diluted with water and extracted with dichloromethane in order to eliminate the aglycones.

The separated aqueous phase was adjusted to pH 8 with 0.1 N NaOH and extracted with dichloromethane.

The organic phase was separated, washed with water, dried over anhydrous sodium sulphate and evaporate in vacuum to small volume. The mixture was separated by chromatography on a column of silica gel, buffered at pH 7 with 0.1 M sodium phosphate, using dichloromethane-ethanol as eluent to give the fluoro derivative 6a, isolated as free base (m.p. 215"C, FD-MS 529 (M+)), Rf 0.31 on TLC Kieselgel F 254 Merck using as eluent the solvent mixture dichloromethane/ethanol (9/1 v/v).

PMR (200 M Hz, CDCI3): 1.34 (dd, 3H, 6.2 Hz), 1.59 (ddd, 1H, J=4.0,13.0,13.0 Hz, H-2'ax), 2 03 (dddd, J= < 1, 5.0, 5.0, 13.0 Hz, 1H, H-2'eq), 2 41 (s, 3H, COCH3), 3.1-3 3 (m, 1H, H-3'), 3.85 (ddd, J=50.0, 9.4, 9.4 Hz, 1H, H-4'), 3.9-4.1 (m, 1H, H-5'), 4.07 (s, 3H, OCH3), 5.27 (dd, J=2.2, 4 Hz, 1H, H-7), 5.44 (ddd, J= < 1, 3.0, 4.0 Hz, 1H, H-1') and the fluoro derivative 7a as free base (m p. 210 dec. FD-MS 529 (my), RF 0.20 on TLC Kieselgel F 254 (Merck) using as eluent the solvent mixture dichlomethane/ethanol (9/1 v/v).

PMR (200 M Hz, CDCI3) 1.45 (dd, J=6.4, 24.8 Hz, 3H, CH3CHF), 1.83-1.96 (m, 1H, H-2'), 2.17 (ddb, J=6.0, 13.0 Hz, 1H, H-2'), 2.39 (s, 2H, COCH3), 3.57-3.82 (m, 2H, H-3', H-4'), 4.06 (s, 3H, OCH3), 4.78 (ddq, J=50.0, 6.4, 6.4 Hz, 1H, H-5'), 5.17 (dd, J=2 9, 4.0 Hz, 1H, H-7), 5.68 (bd, J = 5.5 Hz, 1H, H-1').

The free amino base 6a and 7a were transformed into the corresponding hydrochloride by treatment with methanolic HC1.

EXAMPLE 4 Preparation of 2',3',4' 6'-tetradeoxy-3'-amino-4'-fluoro- L-arabinohexopyranosyl-doxorubicin (8a) A solution of 6a in a mixture of methanol and dioxane as described in US Patent 3,803,124, was treated with bromine to give 14-bromo derivative which by treatment with sodium formate afforded 8a converted by treatment with methanolic HCI into the hydrochloride.

EXAMPLE 5 Preparation of 2,3'5,6'-tetradeoxy-3'-amino-5'-fluoro- hexofuranosyl-doxorubicin (9a) Following the procedure described in Example 4, 7a was converted into its doxorubicin analog isolated as hydrochloride by treatment with methanolic HCI.

EXAMPLE 6 Preparation of 4demethoxy-4'-epi-4tO-trifluoromethane- sulfonate-N-(diphenylrnethylene)-daunorubicin (3b) The title compound was prepared starting from 4-demethoxy- 4'-epi-daunorubicin (1b) via its N-diphenylmethylene derivative 2b prepared as described in the Example 1.

Treatment of 2b with trifluoromethanesulfonic anhydride in anhydrous dichloromethane and dry pyridine gave, after removal of the solvent, 4-demethoxy-4'-epi-4'-O-trifluoro- methanesulfonate-N-(diphenylmethylene) daunorubicin (3b).

EXAMPLE 7 Preparation of 4-demethoxy-2',3',4' 6'-tetradeoxy-3'-amino- 4'-fluoro-L-arabino-hexopyranosyl daunorubicin (sub) and 4-demethoxy-2 ',3 ', 5', 5'-tetra deoxy-3'-amino-5'-fluornhexo-furanosyi daunorubicin (7b) Compound 3b was transformed in its fluoro derivatives 6b and 7b by treatment with anhydrous n-tetrabutyl- ammonium fluoride in a mixture of an hydros dichloromethane and dry acetonitrile as described in Example 3.

Acidic hydrolysis of the mixture gave, after chromatography on a column of silica gel buffered at pH 7 using dichloromethane-ethanol as eluent, the pure 4-demethoxy-2',3',4',6'-tetradeoxy-3'-amino-4'-fluoro-L- arabino-hexopyranosyl daunorubicin (6b) and 4-demethoxy-2',3',5',6'-tetradeoxy-3'-amino-5'-fluoro-hexo- furanosyl daunorubicin (7b).

Both compounds were transformed into the hydrochloride derivative by treatment with methanolic HCI.

EXAMPLE 8 Preparation of 4-dernethoxy-2 ',3 ',4', 6'-tetradeoxy-3'- -amino-4'ifluoro-L-arabino-hexopyranosyl doxorubicin t8b) The title compound was prepared from 6b according to the procedure described in US Patent 3,803,124 and converted into the hydrochloride by treatment with methanolic HCI.

EXAMPLE 9 Preparation of 4-dernethoxy-2 ',3',5', 6'-tetradeoxy-3 '-amino- -5'-fluoro-hexofuranosyl doxorubicin (9b) The title compound was prepared from 7b according to the procedure described in US Patent 3,803,124 and converted into the hydrochloride by treatment with methanolic HCI.

Claims (21)

1. An antitumoral anthracycline glycoside having the general formula 1 or II:

wherein RI represents an hydrogen atom or a methoxy group and R2 represents an hydrogen atom or an hydroxy group or a pharmaceutically acceptable acid addition salt thereof.

2. A compound according to claim 1, which is 2',3',4',6'- tetradeoxy-3'-amino-4'-fluoro-L-arabino-hexo- pyranosyl- daunorubicin or a pharmaceutically acceptable acid addition salt thereof.

3. A compound according to claim 1, which is 4-demethoxy- 2',3',4',6'-tetradeoxy-3'-amino-4'4luoro-L- hexopiranosyl daunorubicin or a pharmaceutically acceptable acid addition salt thereof.

4. A compound according to claim 1, which is 2',3',4',6'- tetradeoxy-3'-amino-4',fluoro-L-arabino-hexopyranosyl- doxorubicin or a pharmaceutically acceptable acid addition salt thereof.

5. A compound according to claim 1, which is 4-demethoxy- 2',3',4',6'-tetradeoxy-3'-amino-4'fluoro-L- arabino- hexopyranosyl doxorubicin or a pharmaceutically acceptable acid addition salt thereof.

6. A compound according to claim 1, which is 2',3',5',6'- tetradeoxy-3'-amino-5'-fluoro-hexofuranosyl daunorubicin or a pharmaceutically acceptable acid addition salt thereof.

7. A compound according to claim 1, which is 4-demethoxy- 2',3',5',6'-tetradeoxy-3'-amino-5'-fluoro- hexofuranosyl daunorubicin or a pharmaceutically acceptable acid addition salt thereof.

8. A compound according to claim 1, which is 2',3',5',6'-tetradeoxy-3'-amino-5'-fluoro-hexofuranosyl doxorubicin or a pharmaceutically acceptable acid addition salt thereof.

9. A compound according to claim 1, which is 4-demethoxy- 2',3',5',6'-tetradeoxy-3'-amino-5'-fluoro- hexofuranosyl doxorubicin or a pharmaceutically acceptable acid addition salt thereof.

10. A process for producing a compound of Formula (I) or (II) which process comprises protecting the amino group of a compound of formula (V)

wherein R1 is as defined in relation to Formulae I and II, converting the 4'-hydroxy group into a fluoro substituent, removing the amino protecting group and, if required converting the 14-methyl group into a hydroxy methyl group, and optionally thereafter forming a pharmaceutically acceptable acid addition salt.

11. A process for the preparation of a giycosidic compound of the general formula I or II, according to claim 1, wherein R1 is an hydrogen atom or a methoxy group and R2 is an hydrogen atom or an hydrogen atom or an hydrogen group, characterised in that 4'-epi-daunorubicin or its 4-demethoxy analogue, dissolved in dichloromethane, are reacted with benzophenone imine, at a temperature of 35"C, to obtain their corresponding 4'-epi-N-(diphenylmethylene) derivatives which are subsequently treated, in anhydrous dichloromethane and in the presence of dry pyridine, at a temperature of -10"C under nitrogen, with trifluoromethane sulfonic anhydride to give the corresponding 4'-epi-N-(diphenylmethylene)-4'-Otrifluoromethanesulfonate which, in an hydros dichloro- methane, at a temperature of 0 and under nitrogen, are reacted, for a time of 24h, with anhydrous n-tetrabutyl-ammonium fluoride to obtain, via the subsequent displacement of the trifluoromethanesulfonate leaving group, a mixture of the N-protected derivatives of formula I and II (RI=H, OCH3; R2=H), subjecting said mixture to a mild acidic hydrolysis, separating the so obtained free glycosidic bases by chromatography on a column of buffered silica gel and isolating them as their respective hydrochlorides which, if desired, are eventually converted via their 14-bromo derivatives and subsequent hydrolysis with sodium formate into their doxorubicin analogues of formula I and II (RI=H, OCH3; R2=OH) which are as well isolated as their corresponding hydrochlo rides.

12. A pharmaceutical composition comprising as active ingredient an anthracycline glycoside as claimed in any one of claims 1 to 5 or which has been prepared by a process as claimed in any one of claims 10 to together with a pharmaceutically acceptable carrier therefor.

13. A compound of formula (I) or (II) as defined in claim 1 for use in the treatment of the human or animal body by therapy.

14. A compound or salt thereof according to claim 12 for use in treating a tumor.

15. A process for producing a compound as defined in claim 1 and substantially as hereinbefore described with reference to the Examples.

16. A compound useful as an intermediate for producing a compound as claimed in claim 1 and hav ing the formula V

wherein R3 is selected from

wherein R4 is amino or a protected amino group and R5 is a fluoro, hydroxy or trifluoromethyl sulphonyloxy group.

17. A compound as claimed in claim 16 wherein R4 is amine.

18. A compound as claimed in claim 16 wherein R4 is a diphenylmethylenimino group.

19. A compound as claimed in any one of claims 16 to 18 wherein R5 is fluoro.

20. A compound useful as an intermediate for producing a compound of formula (I) as defined in claim 1 and having the formula (III).

21. A compound useful as an intermediate for producing a compound of formula (II) as defined in claim 1 and having the formula (IV)