CA1099706A - Aglycone derivatives of daunomycinone - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to novel aglycones of dauno-mycinone which are useful for the preparation of a new class of daunomycin derivatives which are useful in treating certain mammalian tumors. The aglycones are of the formula II:

Description

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This is a divisional appli.cat:ion o:E Canad.ian pa-tent application serial number 302,421 Eiled on MaY 2, 197~.
SUMMARY OF THE INVENTION
This invention provi.des, i.n one aspect thereof, aylycones of the formula II (which are derivatives o:E dauno-mycinone) 3 (II~

OH O ORl wherein Rl is a lower alkyl having 1 to 4 carbon atoms.
In another of its aspects, the invention provides a new process for the preparation of compounds of the yeneral formula II which comprises:
(a) react:ing a compound of the formula (IV) o OCOOC2H5 o ~ CH3 :~: OCooc2H5 :~ with aluminum trichloride in an oryanic solvent to produce a compound of the formula ~V) O OH o ~ CH3 (V) 3~ OH O OCOOC H
~: QCOOC~H5 2 5 ~L~gg76~
.

1 (b) reacting -the compound oE the formula (V) wi-th a benzyl halide in the presence o a base in an organic solvent at ~ tempera-ture of from about 20C Io about 100C to produce a compound of the formula (VI) ~ C-~3 ~VO

(c) treating the compound of the formula (VI) with a dilute alkaline hydroxide or with a basic resin to produce a compound of the formula (VII) CH2Ci;H5 ~

9 (VII~

2 6 5 OH oR2 ...
wherein R2 is hydrogen when the treatment is carried aut in an aqueous medium and is an alkyl residue when the treatment is carried out in an alcohol solvent, td) reacting the compound of the formula (VII) with a halide of the general formula Rl-Y wherein Rl is defined herein-before and Y is selected from the group consisting of chlorine, bromine and iodine, to produce a compound of the general formula ~VIII~

~' .

~9~

C1~12C6H5 ~ 3 ~VIII~

Rl ~R2 wherein Rl and R2 are defined hereinbefore, 1~ (e) reacting the compound of the general formula (VIII~ with trifluoroacetic acid at room temperature to produce a compound of the formula IIX~

~ ~ 3 OH ORl OR2 wherein Rl and R2 are defined hereinbefore; and ~ (f) hydrolyzing the compound of the formula (IX~ in boiling aqueous trifluoroacetic acid to produce the compound :~ of the general formula ~ and its 7-epimer.
These compounds are useful in the preparation of a new class of daunom~cin derivatives of the formula II):
~:.

, :
-::

-3-~ J'~C}13 ; ~ ~ ~ /j 7~ O~I
0~1 o ~ ~
~ I
37 o ~

~ NH-R
0~ .
wherein Rl is a lower alkyl having rom 1 to 4 carbon atoms and R is hydrogen or a trifluoroacetyl group.
These compounds are prepared from the respective aglycones of the formula II (which are derivatives of daunomyci-; none) by condensation with an N,0-protected daunosamine derivative. The aglycones of the formula II: -;;
O OH ~ ;~

}l3 ¦ H OH II ~ :
)H OR
~1 0 wherein Rl is as defined abover are another aspect of the invention.
The aglycones of the formula II are in turn prepared . from daunomycinone III according to the following sequence:
:, .

~ .

-4-7~ ' ." ~ ., , ~ O O

o ----o ~-- ~ o ~"
o--~-o o-~o H ~q O
I D ~

~\ 3Ul (>"Om~ C~

~ ~ O O

~oO,, ~ocN T

7~

1 wherein Rl is as defined above and R2 is as d~Eined hereinaf-tex.
~s described in co-pending application Serial No.
290,848, filed November 14, 1977, daunomycinone I:[I can be easily conver-ted to the triethoxycarbonyl derivative IV. We have now ~urprisin~ly found that compound IV reacts ~ith aluminum -tri-chloride in an organic solvent such as dichloromethane, chloroEorm and the like, to aEford the bis-phenolic compound V by an un~
expected, simultaneous cleavage of the phenolic methyl ether in the ~-position and of the carbonate moiety in the ll-position.
1~ Compound V is thus the key intermediate of the present synthesis.
In fact, the reaction of compound V with a benzyl halide in the presence of a base such as silver oxide, potassium carbonate and the like, in a suitable organic solvent and at a temperature of 20 to 100C, yields the dibenzyl derivative VI. The latter, on treatment with a dilute alkaline hydroxide or with an activated basic resin such as AGl-X2 and the like, gives rise to the monophenolic compound VII, wherein R~ is hydrogen when the reaction is carried out in aqueous medium, and preferably, is an alkyl residue when an alcohol, such as methanol, is used as the 2Q solvent. Another key step in this synthesis is the reaction of the phenolic hydroxyl group of compound VII (R2 = CH3) with a halide of the general formula Rl-Y, wherein Rl is as defined above and Y is Cl, Br, or I, to afford the new ethers of the formula VIII ~R2 = CH3). This reaction is run in a boiling organic solvent such as dichloromethane, chloroform, dichloro-ethane and the like in the presence of a base such as silver oxide, potassium carbonate and the like. Selective removal of the benzylic groups of compound VIII (R2 = CH3) is achieved by brief treatment with trifluoroace-tic acid at room temperature with the formation of the bisphenolic compound IX (R2 = CH3).
Finally the C-7 methyl e-ther is hydrolyzed in boiling aqueous ~ ~9 ~t~ ~

1 tri:Eluoroacetic acicl to a.Eforcl-the new ~glycon~ 1~, toclether w1.th small amounts o:E the 7-epi.mers -the~eof. 'rhe latter can themselves be transformed into aglycones :[I/ having the 7-~-0~1, foll.owing the equilibra-tion method report~d by Kende in ~.~m.Chem.Soc. g8, 1967 (1976). The bi.ologically ac-tive glycosides of formula I are prepared by con~ensing an aglycone of the formula II (.according to the procedure for the synthesis of glycoside linkages described in Belgian Patent No. 842,930 owned by the unrecorded assignee hereof) with a protec-ted 1-halo-sugar in a suitable organic solvent, such as dichloromethane or chloroform, in the presence of a soluble silver salt as a catalyst. In the present case, the aglycone II is condensed . .
-~ with l-chloro-N,0 bis-trifluoroacetyldaunosamine, to form the N,0 protected glycoside X wherein R1 is as defined above:

J ~ Ol 3 OH 1 q ~O ~ /~

F3 .:~

The N,0 protected glycoside X, on tre~tment with methanol and a catalytic amount of triethylamine, is converted into the N-trifluoroacetyl protected glycoside which can be successively hydrolyzed, by mild exposure to a dllute alkaline hase, to form the free glycosidic base which is finally isolated as the hydrochlorlde. Compounds I display antimitotic activity and they are useful therapeutic agents for the trea~ment of certain mammalian tumors.

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1 DESCRIPTION OL` THE PRF,E'ERRE,D E:MNODCME,N'rS

The followin~ examples are given to illustrate the invention by describiny the preparation o~ compounds accordiny to the invention and -their use, without, however, being a limita-tion thereoE~

X~MP~E 1 4-Demethoxy-4-hydroxy 06,07-bi_ _hox~carb yldauno~ycinone To a solution of 30 g. of o6,o7,0 l-txis-ethoxycarbonyl-daunomycinone in 500 ml. of chloroform, 30 g. of granularaluminum trichloride were added under vigorous stirring. Two further addi-tions, each one o~ 30 g. of aluminum trichloride, were made af-ter 1 hour and 1.5 hours, respectively. After stirring for two hours, the reaction mixture was poured in-to 2 liters of a cold aqueous solution of oxalic acid and extracted with chloroform. Tne organic layer (chloroform) was washed with an aqueous solution of sodium bicarbonate, then with water and finally was dried over sodium sulfate. The solvent was evaporated in vacuo and the residue was crystallized from a mixture of X~ ethyl acetate-benzene -to yield 13 g. of 4-demethoxy-4-hydroxy-06,07-bis-ethoxycarbonyldaunomycinone.

PMR (CDC13): 1.33 and 1.43~ ~two t, CH3-C(ll2)), 2.40~ (s, CH3CO), 4.23 and 4.33~ (two q, CH2-C(CH3)~, 6.13~ (broad s, C-7-H), 6.9-7.8~ (m, 3 aromatic protons~, 12.45 and 13.4~ ~two s, phenolic hydroxyls).
IR (KBrl: 1775, 1750, 1710, 1625, 1600 and 1585 cm 1 4-Demethoxy-4-hydroxy-11-deoxy-4,11-dibenzyloxy-06,07-bis-ethoxycarbonyldaunomycinone A solution o 5 g. oE 4-demethoxy-4-hydroxy-06,07-bis-g9~i~QEà

1 ethoxycarbonyldaunomycinone in 250 ml. oE dichloromethane was treated with 5 ml. of benzyl bromide and 5 g. of silver oxide and re:Eluxed :Eor two hours. After cooling, the reac-tion mixture was ~i:ltered and the solvent evaporated in vacuo. The resulting oily residue ~as washed several times with pe-troleum ether until .it became solid and was then crys-tallized :Erom a mlxture of dichloro-methane-benzene to aEford 6 g. oE 4-demethoxy-4-hydroxy-11-deoxy-4,11-dibenzyloxy-06,07-bis-ethoxycarbonyldaunomycinone.

PMR (CDC13): 1.30 and 1.40~ (two t, CH3-C(H2)), 2.23~ (s, CH3C0), 4.23 and 4.30~ (two q, CH2C(H3)), 5.00 and 5-23~
;~ (two s, 0-CH2-C6(H~)), 6.23~ (broad s, C-7-H), 6.9-7.9~ (m, 3 aromatic protons).
IR (KBr): 1770, 1745, 1717, 1680 and 1590 cm 1 .

4-Demethoxy-4-hydroxy-7,11-bis-deoxy-4,11-dihenzyloxy-7-methoxydaunomycinone ;
A solution of 5 g. of 4-demethoxy-4-hydroxy-11-deoxy-4,11-dibenzyloxy-06,07-bis-ethoxycarbonyldaunomycinone in 15 ml.
of dichloromethane and 100 ml. of methanol was treated with an excess of AGl-X2 resin which had been previously activated with aqueous sodium hydroxide and washed with methanol. The reaction mixture was stirred at room temperature until the starting material had completely reacted, and then lt was filtered and evaporated to dryness. The resulting residue was chromatographed (silica gel; chloroform-acetone 95:5, v/v) to give 3 g. of 4-demethoxy-4-hydroxy-7,11-bis-deoxy-4,11-dibenzyloxy-7-methoxydaunomycinone.

: ;
3~

1 PMR (CDC13): 2.30~ (s, CH3CO), 3.60~ (s, cll3n) / 4.93~ (9, O-CH2-C6(El5) and C-7-H~, 5.31~ (s, 0-CL12-C6(~15)), 7.2-8.0~ (m, 3 aromatic protons), 14.2~ (s, phenolic hydroxyl).
IR (KBr): 1726, 1681, 162~, 1587 and 1572 cm EXL~MPIE 4 4-Deme-thoxy 4-hydroxy-11-deoYy-4,11-diberlzyloxydaunomycinone The title compound was obtained from 4-demethoxy-4-hydroxy-11-deoxy-4,11-dibenzyloxy-06,07 bis ethoxycarbonyldauno-mycinone following the procedure described in Example 3, except ~ that aqueous dichloromethane and wet resin were used in place ; of the methanol~

PMR (CDC13) 2.26~ (s, CH3CO), 4-90~ ~s, 0-CH2-C6(H5)~, 5.30 (s, O-CH2C6(H5) and C--7-H), 6~9--7.9~ (m, 3 aromatic protons), 14.3~ (phenolic OH).

.
4-Demethoxy-4-hydroxy-6,7,11-tris-deoxy-4,11-dibenzyloxy-6,7-dimethoxydaunomycinone 1.5 Grams of 4-demethoxy-4 hydroxy-7,11-bis-deoxy-4,11-dibenzyloxy-7-methoxy daunomycinone were dissolved in 200 ml. of dichloromethane containing 20 ml. of methyl iodide and refluxed under stirring in the presence of 1.5 g. of silver oxide. After 24 hours the reaction mixture was cooled and left to stand overnight at room temperature. The inorganic solid which precipitated was filtered off and the solvent evaporated in vacuo to yield 4-demethoxy-4-hydroxy 6,7,11-tris-deoxy-4,11-dibenzyloxy-6,7-dimethoxydaunomycinone in almost quantitative yield.

~10--1 P~IR (CDCl3): 2-33~ (s, CE13C0~, 3.53 ancl 3.93~ (two s~ C~130),

5.00 and 5.26~ (-two s, 0-C~L2-C6(~l5)), 7~0-7.9~ ;
(m~ 3 aromatic protons).

4-Demethoxy-~-h~ -6,7-bis~deoxy-6 ! 7-dimc thoxydaunomycinone 1.5 Grams of 4-demethoxy-4-hydroxy-6,7,11~tris~deoxy-4,11-diben2yloxy-6,7-dime-thoxydaunomycinone were dissolved in 50 ml.
of trifluoroace-tic acid containing 2% o~ water and the solution l~ was lef-t to s-tand a-t room -temperature for 3 hours. The acid was removed in vacuo and the residue dissolved in the minimum amount of acetone, treated with concentrated aqueous ammonia and finally diluted with ethyl acetate. Af-ter several washings with water, the organic layer was dried over anhydrous sodium sulfate. The solvent was removed in vacuo to afford 4-demethoxy-4-hydroxy-6,7-bis-deoxy-6,7-bis-methoxydaunomycinone in 90~ yield.

PM~ (CDC13): 2.40~ (s, CH3C0), 3056 and 3~90~ ~two s, CH30), 4.80~ (broad s, C-7-H~, 6.7--7.8~ (m, 3 aromatic pro-tons), 12.9 and 13.5~ ~aromatic hydroxyls).

~ EXAMPLE 7 4-Demethoxy-4-hydroxy-6-deoxy-6~methoxydaunomycinone and its ~er A solution of 1.5 g. of 4-demethoxy-4-hydroxy-6,7-bis-deoxy~6,7~bis-me-thoxydaunomycinone in 50 ml. of trifluoroacetic acid containing 2% of water was kept at 60C. for 2 hours. The acid was removed in vacuo and the residue dissolved in acetone and hydrolyzed with concentrated a~ueous ammonia. The reaction mixture was diluted with chloroform, washed with water and 3~ evaporated to dryness. The resulting residue was chroma-tographed ~silica gel, chloroform-acetone 95:5~ v/v) to give two products:

- 1 4-deme-thox~--4-hyclroxy-6-cleoxy-6-metho~ydaunomycinone (RE 0.~3 on silica gel plate; chloroform-acetone 4:1, v/v) ancl :i-ts 7-epimer (RE 0.3) in a ratio of 8:2. :[f desired,the 7-epimer can be readily converted to the natural conEigur.a-tion by treatment wi.th trifluoroace-tic acid.

PMR (CDC13) of 4-demethoxy-4-hydroxy-6-deoxy-6-methoxydaunomy-cinone: 2.43~ (s, CH3C0), 3.96~ (s, CM30), 5.20~ (broad s, C-7-H), 7.0-7.8~ (m, 3 aroma-tic protons), 12.~ and 13.5~ (two s, phenolic hydroxyls).
~ IR (CDC13): 1718, 1625 and 1585 cm 1.

4-Demethoxy-4-hydroxy-6-deoxy-6-methoxy-N-trifluoroacetyl-daunomycin _ _ _ __ To a solution of 1.5 g.of 4-demethoxy-4-hydroxy-6-deoxy-6-methoxydaunomycinone and 1.25 g. of 2,3,6-trideoxy-3-trifluoroacetamido-4-0-trifluoroacetyl-~-L-lyxopyranosyl chloride (l-chloro-N,0-bis-tri:Eluoroacetyldaunosamine) in 100 ml. of anhydrous dichloromethane, a solution of 0.95 g. of silver tri-20. fluoromethanesulphonate in anhydrous diethyl ether was added . dropwise at room temperature under stirring. After 1 hour, the reaction mixture was washed with aqueous NaEIC03 and evaporated to dryness. The resulting residue was dissolved in methanol containing a catalytic amount of triethylamine and left to stand at room temperature for 2 hours. The solvent was removed in vacuo and the residue chromatographed ~silica gel; chloroform acetone 95:5, v/v) to give pure 4-demethoxy-4-hydroxy-6-cleoxy-6-methoxy-N-trifluoroacetyldaunomycin.

PMR (CDC13): 1.31~ (d, CH3-C(H)/ ), 2~40~ (s, CI13-C0), 3.86 (s, CI-I30), 5.20~ (s, C-7-H), 5.36~ (s, C-l'-H) ~ 3~r7~6 i 7.0-7.9~ (m, arorlatic II), 12.83 and 13.53~ (two s, phenolic ~1).

~-Demetho~y-4-hydxoxy-6-deoxy-6-methoxydaunomycin hydrochloride 1.0 Gram of 4-demetho~y-4-hyd:L~oxy-6-deoxy-6-I~letho~cy-N-trifluoroace-tyldaunomycin was dissolved in 50 ml. of aqueous 0.15N NaOH and left to stand for 1 hour at room temperature.
After acidification with oxalic acid and rapid neutralization with aqueous NaHC03, the product was extracted with chloroform and the chloroform extract was evaporated to dryness. The resulting residue was dissolved in dichloromethane and -treated with 1 equivalent of HCl in methanol. Upon the addition of diethyl ether, 4-demethoxy-4-hydroxy-6-deoxy-6-methoxydaunomycin hydro-chloride was precipitated and collected by filtration.
Rf = 0-58 (CHC13-C~30H-H20 = 13:6:1 ~/v~

- 481 nm max PMR (CDC13): 1.26~ ~d, CH3-C(~ ), 2.40~ (s, CH3CO), 3.90~ (s, CH30~, 5.20~ ~s, C-7-H), 5.36~ ~s, C~ l), 7.0-7.9~ (m, aromatic H~

BIOLOGICAL ACTIVITY

4-Demethoxy-4~hydroxy-6-deoxy~6-methoxydaunomycin was tested under t~e auspices of N.C.I., National Institute of Health, Bethesda, Maryland,U.S.A. against Lymphocytic Leukemia P38~
according to the procedure described in Cancer Chemotherapy Reports, Part 3, Vol. 3, page 9 ~19721. The following Table illustrates the antitumor activity of this new anthracycline compound.

The new-compound was compared to daunomycin in a test in which mice infected with tumor cells were injec-ted with the ~13-~9~

two compounds on days 5, 9 and 1.3 ~ith a 4 clay interval between each single injection starting :Erom the fif-th day after tumo:r transplantation in mice.

r.rABLE ___ __ .~ r-Compound Schedule of Dose T/C ~

Days~(i p _ _ mg./kg. ~_ _ Daunomycin.HCl 5,9,13 16 0 148 8.0 129 4.0 120 2.0 119 4-Demethoxy-4-hydroxy- 5,9,13 50.0 124

6-deoxy-6-methoxy- 12 5 129 daunomycln.HCl 6 25 118 3.13 114 _ Modifications and varia-tions can, of course, be made without departing from the spirit and scope of the invention.

.

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Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claied are defined as follows:

1. A process for the preparation of compounds of the general formula (II) wherein R1 is a lower alkyl group having 1 to 4 carbon atoms, which comprises:
(a) reacting a compound of the formula (IV) (IV) with aluminum trichloride in an organic solvent to produce a compound of the formula (V) (V) (b) reacting the compound of the formula (V) with a benzyl halide in the presence of a base in an organic solvent at a temperature of from about 20°C to about 100°C to produce a compound of the formula (VI)
1. Claim 1 continued..,.
   
   (VI) (c) treating the compound of the formula (VI) with a dilute alkaline hydroxide or with a basic resin to produce a compound of the formula (VII) (VII) wherein R2 is hydrogen when the treatment is carried out in an aqueous medium and is an alkyl residue when the treatment is carried out in an alcohol solvent;
   (d) reacting the compound of the formula (VII) with a halide of the general formula R1-Y wherein R1 is defined herein-before and Y is selected from the group consisting of chlorine, bromine and iodine, to produce a compound of the general formula (VIII) (VIII) wherein R1 and R2 are defined hereinbefore, (e) reacting the compound of the general formula (VIII) with trifluoroacetic acid at room temperature to produce a compound of the formula (IX) (IX) wherein R1 and R2 are defined hereinbefore; and (f) hydrolyzing the compound of the formula (IX) in boiiing aqueous trifluoroacetic acid to produce the compound of the general formula (II) and its 7-epimer.
2. 2. A process as claimed in claim 1 further including the step of converting the 7-epimer to the compound of the general formula II by reacting said 7-epimer with trifluoro-acetic acid.
3. 3. Compounds of the general formula II as defined in claim 1 whenever prepared by a process as claimed in claim 1 or 2 or an ohvious chemical equivalent.
4. 4. A process as claimed in claim 1 wherein said organic solvent of claim 1(a) is selected from the group consisting of dichloromethane and chloroform.
5. 5. A process as claimed in claim 1 wherein said base of claim 1(b) is selected from the group consisting of silver oxide and potassium carbonate.
6. 6. A process as claimed in claim 1 wherein said alcohol solvent of claim 1(c) is methanol.
7. 7. A process as claimed in claim 1 wherein said reac-tion of claim 1(d) is conducted in a boiling organic solvent selected from the group consisting of dichloromethane, chloroform and dichloroethane in the presence of a base selected from the group consisting of silver oxide and potassium carbonate.
8. 8. Compounds of the general formula (II) as defined in claim 1 whenever prepared by the process as claimed in claim 4 or 5 or an obvious chemical equivalent thereof.
9. 9. Compounds of the general formula II as defined in claim 1 whenever prepared by the process as claimed in claim 6 or 7 or an obvious chemical equivalent thereof.
   
   10. A process as claimed in claim 1 for preparing 4-demethoxy-4-hydroxy-6-deoxy-6-methoxydaunomycinone which comprises:
   (a) reacting O6, O7, O11-tris-ethoxycarbonyldaunomycinone with aluminum trichloride in an organic solvent;
   (b) reacting the thus produced 4-demethoxy-4-hydroxy-O6, O7-bis-ethoxycarbonyldaunomycinone with benzyl bromide;
   (c) treating the thus produced 4-demethoxy-4-hydroxy-11-deoxy-4,11-dibenzyloxy-O6, O7-bis-ethoxycarbonyldaunomycinone with AGl-X2 resin in methanol;
   (d) reacting the thus produced 4-demethoxy-4-hydroxy-7,11-bis-deoxy-4,11-dibenzyloxy-7-methoxydaunomycinone with methyl iodide;
10. Claim 10 continued.....
    (e) reacting the thus produced 4-demethoxy-4-hydroxy-6,7,11-tris-deoxy-4,11-dibenzyloxy-6,7-dimethoxydaunomycinone with trifluoroacetic acid; and (f) hydrolyzing the thus produced 4-demethoxy-4-hydroxy-6,7-bis-deoxy-6,7-bis-methoxydaunomycinone with trifluoroacetic acid to produce 4-demethoxy-4-hydroxy-6-deoxy-6-methoxy-daunomycinone and its 7-epimer.
11. 11. A process as claimed in claim 10 further including treating the 7-epimer with trifluoroacetic acid to produce 4-demethoxy-4-hydroxy-6-deoxy-6-methoxydaunomycinone.
12. 12. 4-Demethoxy-4-hydroxy-6-deoxy-6-methoxydaunomyeinone whenever prepared by a process as claimed in claims 10 or 11, or an obvious chemical equivalent thereof.