AU643433B2 - A process for the preparation of glucosaminyl-epi- podophyllotoxin derivatives DO NOT SEAL CASE TO LAPSE - Google Patents

Description

COMMONWEALTH OF AUSTRALIA F PATENTS ACT 1952.69 6 4 33 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Priority:

R.

Related Art e• Accepted: Published:

*SSS

OS

S. S 5555 0 Name of Applicant Address of Applicant: Actual Inventor: BEHRINGWERKE AKTIENGESELLSCHAFT of D-3550 Marburg, Federal Republic of Germany.

CENEK KOLAR and KONRAD DEHMEL .Address for Service WATERMARK PATENT TRADEMARK ATTORNEYS.

LOCKED BAG NO. 5, HAWTHORN, VICTORIA 3122, AUSTRALIA Complete Specification for the invention entitled: A PROCESS FOR THE PREPARATION OF GLUCOSAMINYL-EPI-PODOPHYLLOTOXIN

DERIVATIVES

The following statement Is a full description of this invention, including the best method of performing it known to la,- BEHRINGWERKE AKTIENGESELLSCHAFT HOE 89/B 015 Ma 764 Dr. Ha/Sd A process for the preparation of glucosaminyl-epipodophyllotoxin derivatives The present invention relates to a process for the preparation of glucosaminyl-epi-podophyllotoxin derivatives, especially 4-0-(4,6-0-alkylidene-beta-D-glucosaminyl)-4'-demethyl-4-epi-podophyllotoxin derivatives, which, by reason of their cytostatic activity, are suitable for the treatment of cancers.

Glycosyl-epipodophyllotoxins are described in the specialist literature. Two representatives of this class of S substances, etoposide and teniposide, have been intro- 15 duced as pharmaceuticals for the treatment of cancers.

Etoposide derivatives which contain a glucosamine or N,Ndimethylglucosamine carbohydrate unit in place of the glucose unit show a broader spectrum of activity than etoposide on preclinical investigation. Since these compounds are, by reason of the presence of the amino group, readily soluble in aqueous medium, compared with etoposide there are no problems in the preparation of pharmaceutical presentations from them.

e*.

EP-A-0 141 057 and 0 196 618 describe etoposide derivatives which contain a glucosamine or N,N-dimethylglucosamine unit in place of the glucose.

The said application EP-A-0 141 057 also discloses a process in which the compounds according to the invention are prepared by reacting a functionalized beta-glucosamine unit and 4'-0-protected epi-podophyllotoxin with catalysis by BF 3 However, this process is elaborate and entails large losses because the desired epi-podophyllotoxin glycoside is prepared starting from a beta-hydroxyglycosylating component which can be prepared only by an elaborate method and is unstable because of mutarotation.

The subsequent removal of the acyl protective groups and the introduction of the 4",6"-alkylidene group also entails large losses, and requires additional chromatographic purification steps, because of the large number of by-products.

Chemistry Letters, 799-802, 1987, discloses a process for the synthesis of beta-glucosaminyl-epi-podophyllotoxins, in which the glycosylating component is employed as 4,6-O-ethylideneglucosamine derivative. The functionalized glucosamine component, which is in the unstable beta-hydroxy form, yields, after glycosylation of the aglycone and subsequent elimination of the protective groups, the desired beta-glucosaminyl-epi-podophyllotoxin in 33% yield.

It has been found, surprisingly, that the preferred product of the alkylation of 4'-O-Z-4-epi-podophyllotoxin benzyloxycarbonyl) with a functionalized glucosamine unit, which is in the alpha-hydroxy form, with catalysis by BF 3 in an anhydrous organic solvent, preferably ethyl acetate optionally with admixture of 15 other organic solvents is the beta-glycoside. The beta-glycosylation of epipodophyllotoxins, as hitherto described in the specialist literature, takes place i: via the carbonium ion on carbon atom 4 of the aglycone, it being necessary for there to be nucleophilic attack of the beta-hydroxyl group of the glucosamine unit. The alpha-hydroxy form of the glycosylating unit is, because of the 20 anomeric effect, energetically more stable than the beta-hydroxy form, with the alpha-hydroxy glucosamine derivatives being more straightforward to synthesize than the beta-hydroxy analogs, and thus the process according to the invention reprosents a novel and advantageous way for the industrial preparation of betaglucosaminyl-epi-podophyllotoxins.

S 25 The invention has the object of developing a novel process which provides 4-O-(4,6-O-alkylidene-beta-D-glucosaminyl)-4'-O-demethyl-4-epipodophyllotoxin derivatives in good yields and which is simpler than the known 3 processes. In particular, the aim is to develop a novel process for the preparation of a suitable glucosamineglycosylating component as well as novel deacylation processes for removing the acyl protective group from glucosaminyl-epi-podophyllotoxins.

This object is achieved according to the invention by the process for the preparation of a glucosaminyl-epi-podophyllotoxin derivative of the formula I 0' 1

R

2 -f I gR 3 S0

K

MeO Ome

O-R

4 10 in which R' is hydrogen or the acetyl or a mono-, di- or trihalogenoacetyl protective group with halogen being fluorine, chlorine or bromine,

R

2 is hydrogen or (Ci-C 4 )-alkyl,

R

3 is hydrogen, (Ci-C 4 )-alkyl or a benzyloxycarbonyl protective group,

SR

4 is hydrogen, a mono-, di- or trihalogenoacetyl protective group, a benzyloxycarbonyl protective group or a methyl group, and A is Ci-C 4 -alkyl, which comprises reacting a glucosamine derivative of the formula II, which is in the alpha-hydroxy form, /0 II 0 H R' R2.-N I OH R3 4 in which

R

1 and R 3 are acyl protective groups as defined above, and

R

2 is hydrogen and A is C-C 4 -alkyl, with a podophyllotoxin derivative of the formula III

H

a O <oX 0

III

ooneo'one

O-R

4 in which

R

4 is a methyl group or a mono-, di- or trihalogenoacetyl or benzyloxycarbonyl protective group, in the presence of a promoter such as BF 3 .ether or of a tr (C C alkyl il trifluoromethan e nat and of an op-fioalUy Ita Ohifdvre oo e rganic co(VeATS anhydrous organic solventat -50 C to 20 C to give a 4- O-(beta-glucosaminyl)-epi-podophyllotoxin derivative of o. the formula I in which the radicals R 1

R

2

R

3

R

4 and A 15 retain their meaning as defined above, subsequently eliminating the benzyloxycarbonyl protective group by hydrogenolysis using a palladium catalyst, eliminating the acetyl protective group using zinc dichloride or diacetate and eliminating the halogenoacetyl protective 20 groups using a basic anion exchanger in an organic b solvent such as methanol, ethanol, acetone, ethyl acetate or mixtures thereof with water where appropriate, and, where appropriate, reacting the free amino group under the conditions of reductive alkylation with a Ci-C 4 aldehyde in the presence of a hydride to give a mono- or dialkylamino derivative, there being formation of a (beta-glucosaminyl)-epi-podophyllotoxin derivative of the formula I in which R 1 is hydrogen, R 2 and R 3 are hydrogen or (C-C 4 )-alkyl, R 4 is hydrogen or the methyl group and r A is Ci-C 4 -alkyl.

5 The compounds of the formula I which are preferably prepared by the process according to the invention are those in which

R

1 is hydrogen or acetyl or chloroacetyl protective group

R

2 is hydrogen or (Cz-C)-alkyl

R

3 is hydrogen, C-C 4 -alkyl or benzyloxycarbonyl protective group

R

4 is hydrogen, methyl or benzyloxycarbonyl or chloroacetyl protective groups and A is methyl.

The specific procedure for this is as follows: in the first place, starting from the 1,3-di-0-acyl precursor of the formula IV

S

I v 0

R

1

HN

CO-O-CH

2 Ph the glucosamine-glycosylating component of the formula V Avo group, the precursor is treated with a weak organic base CO-O-CH Ph in which R 1 and R 5 are an acetyl or mono-, di- or trihalogenoacetyl protective group and A is Ci-C 4 -alkyl, is prepared in the following manner: when R 5 is an acetyl group, the precursor is treated with a weak organic base such as piperidine or pyridine, and when R 5 is a halogenoacetyl protective group, the precursor is treated with silica gel in a polar organic solvent such as methanol or ethanol.

The glucosamine compound is converted into the energetically more stable alpha form by dissolving the products 6 in a non-polar solvent such as chloroform, dichloromethane.

The glycosylation of a podophyllotoxin derivative of the formula III with the glucosamine unit of the formula V preferably takes place in ethyl acetate, where appropriate with admixture of dichloromethane, chloroform, ether or acetone, in the presence of 1 to 50 equivalents, preferably 20 to 30 equivalents, of BF 3 -ether e: tri-- (C3 C 4 al-k-loilyl triflu.oromothanoiulfoCnac at -50°C to 20°C, preferably at -30 0 C to -15"C. A molecular sieve can be used, where appropriate, as acid trap or drying agent.

The elimination of the protective group from the glucosaminyl-epi-podophyllotoxin derivative of the formula I is carried out as follows: The benzyloxycarbonyl protective group is eliminated by hydrogenolysis using palladium/carbon or palladium/barium sulfate in methanol, ethanol, acetone or ethyl acetate.

The acetyl protective group is eliminated using anhydrous zinc diacetate or dichloride in methanol or ethanol at :20 the reflux temperature.

0**6 The halogenoacetyl protective groups, preferably the chloroacetyl protective group, are eliminated using a basic anion exchanger such as Dowex, preferably 1x8, in an organic solvent such as methanol, ethanol, acetone, 25 ethyl acetate, preferably methanol, or mixtures thereof.

The products of the formula I, which have a free amino group on carbon atom are converted into mono-, but preferably into di-(C 1

-C

4 )-alkylamine derivatives by reductive alkylation with a Ci-C 4 -aldehyde and a hydride such as sodium cyanoborohydride.

The examples which follow are intended to explain the invention without, however, confining it to the compounds mentioned.

7 Example 1 Preparation of 2-N-benzyloxycarbonyl-1,3-di-0-acyl-4,6- O-ethylidene-alpha,beta-D-glucosamine derivatives 2-N-Benzyloxycarbonyl-4,6-0-ethylidene-D-glucosamine (compound 1) The title compound was prepared by the process of H.

Saito et al., as described in Chemistry Letters, 799-802 (1987), as follows: starting from D-glucosamine hydrochloride and benzyloxycarbonyl chloride, in the presence 10 of 2 equivalents of NaOH in water, 2-N-benzyloxycarbonyl- D-glucosamine was prepared and subsequently converted with acetaldehyde, with catalysis by H2SO 4 into the title **j compound.

1,3-Di-O-acetyl-2-N-benzyloxycarbonyl-4,6-0-ethylidenealpha,beta-D-glucosamine (compound 2) Compound 1 was reacted with acetic anhydride and pyri- "e"e dine, by the acylation process customary in carbohydrate chemistry, to give the title compound.

G*s 2-N-Benzyloxycarbonyl-l,3-bis-0-chloroacetyl-4,6-0ethylidene-alpha,beta-D-glucosamine (compound 3) 33 g (97.2 mmol) of compound 1 were dissolved in 1,000 ml 'I of dichloromethane and 300 ml of pyridine and, while stirring at 0 C, 2.4 equivalents of chloroacetyl chloride dissolved in 500 ml of dichloromethane were added in portions. After 14 h, the reaction mixture was washed thoroughly with sodium phosphate buffer, pH 7.5, and the organic phase was dried and evaporated in vacuo. The residue was purified by column chromatography on silica gel (eluent: dichloromethane/acetone, 10:1).

Yield: 45.4 g 8- 1 H NMIR: (300 MHz, H,H-COSY, CDC1 3 delta: 7.4-7.3(m, Ph), 6.20 1H, J(1,2) 3.8 Hz, H-14), 5.28 (dd, 1H, J(2,3) 10.4 Hz, J(3,4) =9.6 Hz, H-3i), 5.11 1H1, Jg 11.5 Hz, CHih), 5.03 lH, Jg, CHh) 5.02 IH, J(2,NH) 9.5 Hz, NH 4.70 1H, J(CH,Me) 5 Hz, 4.23 (ddd, 1H, J(2,NH), 4.15 2H, ClCH2), 4.13 (dd, 1H, Jg 10.5 Hz, J(5,6e)= Hz, H-6e), 4.02 1H, Jg 15 Hz, ClCH,-.A), 3.92 (d, 1H, Jg, ClCH.2-B), 3.79 (ddd, 1H, J(5,6a) 10 Hz, J(5.6e), 1 3.58 (dd, 1H, 3.52 0:00 (dd, 1H, Jg, J(5,6a), H-a) 1.33 3H, J(Me,CH), MeC=) Example 2 Preparation of 3-O-acyl-2-N-benzyloxycarbonyl-4, ethylidene-alpha-D-glucosamine derivatives 3-O-Acetyl-2-N-benzyloxycarbonyl-4 ,6-O-ethylidene-alpha- D-gluocosamine (compound 4) 2.11 g (5 mrmol) of compound 2 were dissolved in 40 ml of THF, and 0.5 ml of piperidine was added. After the reaction mixture had been stirred for 12 h it was evaporated in vacuo and then distilled with toluene. The residue was dissolved in chloroform, the solution was 0:0 thoroughly washed with ice-water, and the organic phase was dried over sodium sulfate. The product was purified by column chromatography on silica gel (eluent: dichloromethane/acetone Yiel 1.67 g of syrup, 3 +29.10 (c=l in chloroform) 2-N-Benzyloxycarbonyl-3-0-chloroacetyl-4 alpha-D-glucosamine (compound 37 g (75.2 mmol) of compound 3 were dissolved in 500 ml of methanol, and 74 g of silica gel 60 (40 63 pm) were added. The suspension was stirred at RT for 3 h. TLC: dichloromethane/ethyl acetate 1:1. The reaction mixture 9was filtered, and the solid phase was washed with methanol. The residue from evaporation of the organic phase was dissolved in dichioromethane/ethyl acetate and filtered through 50 g of silica gel. The organic phase was evaporated in vacuo and then distilled with chloroform. Yield: 28.31 g of syrup,, (t]2 5 +32.90 (c=1 in ethyl acetate) 1H NMR (300 MHz,, HH-COSY,, CDCl 3 delta: 7.38-7.30 (in, Ph) 5.32 (dd, l1H, J(2,3) 11 Hz, J(3,4) 10 Hz, 11-3), 5.26 1H, J(2,NH) 10 Hz, NHj), 5.23 II, J(1,2) 3.5 Hz, 5.11 1H, Jg =12 Hz, CHPh), 5.03 (d, sees1H, Jg 12 Hz, CHjh), 4.69 1Hi, J(Me,CH) 5 Hz, 0 6:00: 4.09 (dd, 1H, J(5,6e) 4.7 Hz, Jg 10 Hz, H-) *4.04 1H, J(2,NH), 4.02 1H, 5 Jg 14.6 Hz, CgJH), 3.99 (ddd, 1H, J(4,5) 10 Hz, J (5,6a) 10 Hz, J(5,6e) 4.7 Hz, 3.92 1H, Jg, CiCH), 3.52 (dd, 1H, J(516), Jg, H-a) 3.48 (dd, 1H, 1.32 3H, J(Me,CH), MeC).

Example 3 Glycosylation of podophyllotoxin derivatives 600 006*4-0- (3-0-Acetyl-2-N-benzyloxycarbonyl-4, beta-D-glucosaminyl '-O-benzyloxycarbonyl-4 '-0-demethyl-4-epi-podophyllotoxin (compound 6) 2.8 g (5.2 mmol) of 4'-0-benzyloxycarbonyl-4'-0-demethyl- 4-epi-podophyllotoxin and 1.9 g (5.2 mmol) of compound 4 were dissolved in 300 ml of ethyl acetate. 5 g of 4A molecular sieves were added and then the reaction mixture was cooled to -18 0 C, and 39 g of BF 3 .ether were added.

The reaction mixture was stirred at -18*C for 6 h (TLC: dichioromethane/acetone 10:1). It was then neutralized with 40 ml of triethylamine and filtered. The organic phase was evaporated in vacuo, the residue was dissolved in chloroform, and the solution was thoroughly washed with water. The organic phase was dried over sodium 10 sulfate and evaporated. The resulting product was purified by column chromatography on silica gel (eluent: dichloromethane/acetone 10:1).

Yield: 3.6 g (78%) 1H NMR (300 MHZ, H,H-COSY, CDC1 3 delta: 7.38-7.19 (mn, Lh) 6.68 1H, 6.44 1H, 6.18 (s, 2H, H-2 and H-61), 5.88 1H, H-i5a), 5.73 1H, 5.20 2H, CH2Ph), 5.12 (dd, 1H, J(211,3'') Hz, H-311), 5.00 1H, Jg 12.5 Hz, CHd'h-A), 4.84 1H, Jg, CH 9 Ph-B), 4.82 1H, J(3,4) 3 Hz, H-4), 4.79 1H, NH) 10 Hz, NH), 4.69 1H, 0000 J(111,211) 8.5 Hz, 4.69 1H, J(CH,Me) Hz, MeCH=), 4.45 1H, J(1,2) 5 Hz, 4.41 (dd, Ii, J(3,lla) 9 Hz, Jg 9 Hz, H-1ha), 4.18 (dd, IH, Jg, J(3,llb) =7 Hz, H-llb), 4.15 (dd, 1H, Jg =10 Hz, =45HH-6''e), 3.60 3H, Me) 3.56 (ddd, 1H, NH), 3.54 (dd, 1H, Jg, 10 Hz, 3.40 (dd, 1H, J(411,5'') 9.5 Hz, 3.33 (ddd, 0020 1H, 3.19 (dd, 1H1, J(2,3) 14 Hz, 2.77 (in, 1H, 0 J(3,lla), J(3,llb), 1.97 3H, acetyl), 1.28 3H, J(CH,Me) 5 Hz, MeC=).

4' -O-Benzyloxycarbonyl-4-O- (2-N-benzyloxycarbonyl-3-Ochloroacetyl-4 ,6-O-ethylidene-beta-D-glucosaninyl) -41-0demethyl-4-epi-podophyllotoxin (compound 7) 13 g (25 inmol) of 4'-O-benzyloxycarbonyl-4'-O-demethyl- 4-epi-podophyllotoxin and 10 g (25 minol) of compound were dissolved in. 400 ml of dichloromethane /ethyl acetate 1:1, and 23 g of 4 A molecular sieves were added. The reaction mixture was cooled to -18 0 C and, while stirring, ml of BF 3 .ether were added in portions. After stirring at -18 0 C for 4 h, a further 4.0 g of aglycone, dissolved in 50 ml of ethyl acetate, were added. After 10 h, 80 ml of triethylanine were added to the reaction mixture at -18 0 C. The reaction mixture was filtered and evaporated 11 in vacuo. The residue was dissolved in chloroform and thoroughly washed with ice-water. The organic phase was dried over sodium sulfate and evaporated in vacuo. The product was purified by column chromatography on silica gel (eluent: dichloromethane/acetone 15:1). Yield: 17 g 20 =D 250 (c=0.2 in CHCl 3 Melting point: 140 142 0

C

1 H NMR (300 MHz, H,H-COSY, CDCl 3 delta: 7.30-7.44 (in, Phi), 6.74 iH, iH5), 6.50 1H, 6.24 (s, 2H, and H-61), 5.93 1H, H-i5a), 5.76 iH, H-15b), 5.33 (dd, IH, J(21',311) 10 Hz, J(311,411) .me.

Hz, 5.26 2H, ChPh), 5.05 iH, Jg 12.5 0:000:Hz, CH-Ph-A), 4.93 1H, Jg 12.5 Hz, CH-Ph-B), 4.89 15 iH, J(111,2'') 7.5 Hz, 4.89 1H, J(3,4) 3 Hz, 4.89 iH, 9.5 Hz, MH), 4.70 *0 iH, J(Me,CH) 5 Hz, Me-CH=), 4.52 iH, J(1,2)= o* 5.3 Hz, 4.45 (dd, 1H, Jg 9 Hz, J(3,lla) 10 Hz, H-11a), 4.24 (dd, 1H, Jg, J(3,llb) 7 Hz, H-llb), 4.22 (dd, iH, Jg 10.5 Hz, 4.5 Hz, 4.06 1H, Jg =15 Hz, ClAc), 3.99 1H, Jg 15 Hz, 046 ClAc), 3.66 3H, Me) 3.60 (dd, iH, 9 me* Hz, 9 Hz, 3.23 (dd, iH, J(2,3) 14 0:00Hz, 2.83 (mn, iH, J(3,iia), **to J(3,iib), g-3)?j 1.34 3H, J(Me,CH) 5 Hz, Me-).

:00.25 4-O-(2-N-Benzyloxycarbonyl-3-O-chloroacetyl-4,6-O-ethyli: iethyl-4-epi-podophyllotoxin (compound 8) The title compound was prepared starting from 200 mng (0.42 mmol) of 4 '-O-chloroacetyl-4 '-O-demethyl-4-epipodophyllotoxin and 175 mng (0.42 inmol) of compound 5 by the procedure for the preparation of compound 7 and was characterized by 1 H and 13C NI4R spectra.

Yield: 257 mg (2-N-Benzyloxycarbonyl-3-O-chloroacetyl-4 dene-beta-D-glucosaminyl)-4-epi-podophyllotoxin 12 (compound 9) The title compound was prepared starting from 150 mg (0.36 mmol) of podophyllotoxin and 150 mg (0.36 mmol) of compound 5 by the procedure for the preparation of compound 7 and was characterized by 1 H and 13C NMR spectra. Yield: 190 mg Example 4 Deacylation of the glucosaminides *o 4-0-(2-N-Benzyloxycarbonyl-4,6-0-ethylidene-beta-D- 10 glucosaminyl) -4'-O-benzyloxycarbonyl-4' -O-demethyl-4-epipodophyllotoxin (compound a) Deacylation of the 3"'-0-chloroacetyl derivative *(compound 7) g (2.4 mmol) of compound 7 were dissolved in 500 ml 15 of methanol, and 5 g of Dowex 1x8 ion exchanger were ooo added. After stirring at room temperature for 2 h, the resin was filtered off and thoroughly washed with methanol. The organic phase was evaporated in vacuo, and the residue was dissolved in chloroform and thoroughly washed. The organic phase was dried over sodium sulfate and evaporated in vacuo. Yield: 1.95 g [C] 0 -65.4° (c=l in chloroform) The title compound was characterized by NMR spectroscopy.

b) Deacylation of the 3"-0-acetyl derivative (compound 6) 600 mg (0.61 mmol) of compound 6 were dissolved in 50 ml of dry methanol, and 83 mg of zinc dichloride were added.

The reaction mixture was refluxed for 3 d. After the usual working up, the product was purified by column chromatography. Yield: 377 mg 13 4-0-(2-N-Benzyloxycarbonyl-4,6-0-ethylidene-beta-Dglucosaminyl)-4-epi-podophyllotoxin (compound 11) 190 mg (0.234 mmol) of compound 9 were deblocked with Dowex to give the title compound by the procedure for the deacylation of compound 7.

Yield: 160 mg (93%) Example Elimination of the N- or 0-benzyloxycarbonyl protective group by hydrogenolysis 4'-0-Demethyl-4-epi-4-0-(4,6-0-ethylidene-beta-D-glucosaminyl)-podophyllotoxin (compound 12) 1.5 g (1.88 mmol) of compound 10 were dissolved in 100 ml of methanol, and 0.45 g of palladium/carbon was added.

The reaction mixture was hydrogenated at room temperature under atmospheric pressure for 1 h. The mixture was.

filtered and evaporated in vacuo. The product crystallizes from methanol/ethyl acetate. Yield: 0.95 g -115.4" (c=l in methanol) Melting point: 202 204"C 4-Epi-4-0-(4,6-0-ethylidene-beta-D-glucosaminyl)-podophyllotoxin (compound 13) 0 Starting from 160 mg (0.217 mmol) of compound 11, the title compound was hydrogenated and worked up by the procedure for the preparation of compound 12. Yield: 117 mg 14 Example 6 Reductive alkylation of 2''-amino derivatives 4'-O-Demethyl-4-0-(2-N,N-dimethyl-4,6-0-ethylidene-beta- D-glucosaminyl)-4-epi-podophyllotoxin (compound 14) 2.5 g (4.25 mmol) of compound 12 were dissolved in 200 ml of methanol, and 4 ml of a 37% strength aqueous formaldehyde solution and 1.06 g of sodium cyanoborohydride were added. The reaction mixture was stirred for 1 h and then evaporated in vacuo, and the residue was purified by 10 column chromatography on silica gel (eluent: dichloromethane/methanol 10:1). Yield: 2 g [a]20 -113.2° (c=l in chloroform) *0 4-0-(2-N,N-Dimethyl-4,6-0-ethylidene-beta-D-glucosaminyl)-4-epi-podophyllotoxin (compound The title compound was prepared starting from 110 mg (0.18 mmol) of compound 13 by the procedure for the preparation of compound 14. Yield: 95 mg *0 s*

Claims (9)

1. A process for the preparation of a glucosaminyl-epi- podophyllotoxin derivative of the formula I R '3 ^O-O K MeO OMe 0-R 0 in which R i is hydrogen or the acetyl or a mono-, di- or trihalogenoacetyl protective group with halogen being fluorine, chlorine or bromine, R z is hydrogen or (Cl-C4)-alkyl, group or a methyl group, and *A is C,-C-alkyl the formula II, which is in the alpha-hydroxy form, A O O '0 11 R' R-NOH R3 in which R i and R 3 are acyl protective groups as defined above, and R 2 is hydrogen and A is C 1 -C 4 -alkyl, A is C-C-alkyl, 16 with a podophyllotoxin derivative of the formula III H I o x III MeO OMe neo' One O-R 4 in which R 4 is a methyl group or a mono-, di- or trihalogeno- acetyl or benzyloxycarbonyl protective group, in the presence of a promoter -se- as BF 3 .ether e-r f r 1 C 4 alcyloilyl trifluoromothanoulfonato and of an anhydrous organic solvent at -50C to 20°C to give a derivative of the formula I in which the radicals R 1 R 2 R 3 R 4 and A retain their meaning as defined above, subsequently eliminating the benzyloxycarbonyl pro-. tective group by hydrogenolysis using a palladium catalyst, eliminating the acetyl protective group using zinc dichloride or diacetate and eliminating the halogenoacetyl protective groups using a basic anion exchanger in an organic solvent such as methan- ol, ethanol, acetone, ethyl acetate or mixtures thereof with water where appropriate, and, where appropriate, reacting the free amino group under the conditions of reductive alkylation with a Ci-C 4 aldehyde in the presence of a hydride to give a mono- or dialkylamino derivative, there being formation of a 4-0- (beta-glucosaminyl) -epi-podophyllotoxin deriva- tive of the formula I in which R 1 is hydrogen, R 2 and R 3 are hydrogen or (C 1 -C 4 )-alkyl, R 4 is hydrogen or the methyl group and A is Ci-C 4 -alkyl.

2. The process as claimed in claim 1, in which STij R 1 is hydrogen or the acetyl or a chloroacetyl protective group, 17 @06w S p. S S. Si R 2 is hydrogen or (Ci-C 4 )-alkyl, R 3 is hydrogen, (Ci-C 4 )-alkyl or the benzyloxycar- bonyl protective group, R 4 is hydrogen, methyl or benzyloxycarbonyl or chloroacetyl protective groups and A is methyl, wherein a glucosamine derivative of the formula II which is in the alpha-hydroxy form and in which R 1 is a chloroacetyl group, R 2 is a hydrogen atom, R 3 is a benzyloxycarbonyl group and A is a methyl group is reacted with a podophyllotoxin derivative of the formula III in which R 4 is a methyl group, chloroacetyl or benzyloxycar- bonyl protective group, in the presence of BF 3 .ether or tri (C C 4 al.1Yilyl -triflurmmthanfeoulf natc in an organic solvent at C to -10 C to give a podophyllotoxin derivative of the formula I, and the compound is used for the preparation of another compound of the formula I.

3. The process as claimed in claim 1. r, in which R 1 is the acetyl or a mono-, di- or trihalogeno- acetyl protective group with halogen being fluorine, chlorine or bromine, R 2 is a hydrogen atom, R 3 is a benzyloxycarbonyl protective group, R 4 is a mono-, di- or trihalogenoacetyl or benzyl- oxycarbonyl protective group or methyl group and A is Ci-C 4 -alkyl, wherein a glucosamine derivative of the formula II which is in the alpha form and in which R 1 R 2 R 3 and A are as defined above is reacted with a podophyllo- toxin derivative of the formula III in which R 4 is as defined above, in the presence of a promoter such as BF. ether r a t alylil triflur the 5 55n* @6S5 ;5 *5 S S 5* 5 p 0 18 -sculfonato and of an anhydrous organic solvent at to 20°C, preferably at -20 0 C to -30 0 C, where appropriate with the addition of a drying agent such as a molecular sieve.

4. The process as claimed in claim 3, in which BF 3 .ether is employed as promoter.

The process as claimed in claim 3, in which ethyl acetate or a mixture thereof with another solvent such as dichloromethane, acetone or ether is used as organic solvent.

6. A process for the preparation of a glucosamine deriv- I ative of the formula II which is in the alpha form and in which R 1 is an acyl protective group R 2 is hydrogen R 3 is benzyloxycarbonyl protective group and A is C 1 -C 4 -alkyl which comprises treating a 1,3-di-0-acyl-4,6-O-alkyl- idene-2-N-benzyloxycarbonyl-alpha,beta-D-glucosamine derivative of the formula IV A l ik 0 R HN CO-O-CH 2 Ph in which R 1 and R 5 are an acyl protective group as defined above, R 2 is hydrogen, R 3 is the benzyloxycarbonyl protective group and A is Ci-C 4 -alkyl with an organic base such as piperidine or pyridine or with silica gel in a polar solvent such as methanol or ethanol, resulting in a compound of the formula II. 19

7. A 3 G aey 1 4, 6-a--1 die2bize'Y alpha-D-glucosamine derivative of the formula II i which R' is acetyl or mono-, di- or trihalogenoace 1 with halogen being fluorine, chlorine or omine and A is Cl-C 4 -alkyl.

8. A derivative as claimed in cla' 7, in which R 1 is the acetyl or chlo acetyl protective group and A s etyl

9. 4-0-(4,6-0-A ylidene-beta-D-glucosaminyl)-4-epi- S podophyll oxin of the formula I in claim 1 with A CS.4 1 10o-460Akldn---iehlbt--lcsmn ylC-p-oohlltxno h oruaIi li wit A ,G a~Y HAWiTHOARC. VCTOI 3122.