WO2001009129A2

WO2001009129A2 - 1h-pirido[3, 4-b]indol-1-one derivatives

Info

Publication number: WO2001009129A2
Application number: PCT/EP2000/007279
Authority: WO
Inventors: Ernesto Menta; Nicoletta Pescalli; Silvano Spinelli
Original assignee: Novuspharma S.P.A.
Priority date: 1999-08-03
Filing date: 2000-07-28
Publication date: 2001-02-08
Also published as: WO2001009129A3; IT1313592B1; ITMI991740A0; AU6831500A; ITMI991740A1

Abstract

Compounds of formula (I) wherein: R is hydrogen; C1-C6 alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; C5-C6 cycloalkyl; aralkyl; heteroalkyl; aryl; heteroaryl; R1 is hydrogen; C1-C6 alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; C5-C6 cycloalkyl; aralkyl; heteroalkyl; R2 is hydrogen; C1-C6 alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; C5-C6 cycloalkyl; aralkyl; aryl; heteroaryl; heteroarylalkyl; C1-C6 acyl; X is one or more groups independently selected from hydrogen, C1-C6 alkyl, hydroxy, C1-C4 alkoxy, C1-C3 haloalkoxy, amino, C1-C3 alkylamino, C1-C3- acylamino, C1-C3 alkylsulfonylamino, halogen, nitro, cyano, carboxy, C1-C3 alkoxycarbonyl, sulfonyl, C1-C3- alkylsulfonyl, aminosulfonyl, C1-C3-alkylaminosulfonyl, trifluoromethyl with antitumor activity.

Description

1H- PIRIDO [ 3 , 4 - B] INDOL - 1 - ONE DERIVATIVES

The present invention relates to lH-pyrido [3 , 4- b] indol-1-one derivatives and to the pharmaceutical compositions containing them.

1H—Pyrido [3 , 4b] indol-1-one derivatives substituted on the phenyl ring with at least one OH, OCH₃ group or with an aminopropoxy residue, such as the compounds 5-hydroxy-2- methyl-lH-pyrido [3 , 4-b] indol-1-one, 5-methoxy-2 -methyl -1H- pyrido [3 , 4-b] indol-1-one, 6-methoxy-2 -methyl -IH-pyrido- [3 , 4-b] indol-1-one, 7-methoxy-2-methyl -lH-pyrido [3 , 4- b] indol-1-one and 5- [3 - [ (1 , 1-dimethylethyl) amino] -2 - hydroxypropoxy] -2-methyl-lH-pyrido [3 , 4-b] indol-1-one are disclosed in the following documents: EP 705831, DE2626889, Synthesis 1980, (5), 372-274 and J. Chromatography , 1967, 31 (2) , 446-454. None of these compounds has been reported to have antitumor activity.

It has now been found that some lH-pyrido [3 , 4-b] indol- 1-ones have antitumor activity, particularly against colon and lung tumors . The present invention relates to compounds of formula (I) :

wherein :

R is hydrogen; C-^-Cg alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; ^C5"^cg cycloalkyl; aralkyl; heteroalkyl; aryl; heteroaryl;

R₁ is hydrogen; C₁-Cg alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; ^C5^_C6 cycloalkyl; aralkyl; heteroalkyl ,- R₂ is hydrogen; C₁-C₆ alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; C₅~Cg cycloalkyl; aralkyl; aryl; heteroaryl; heteroarylalkyl ; C-^-Cg acyl; X is one or more groups independently selected from hydrogen, ^cι ^{~ c} _β alkyl, hydroxy, ^cι"^C4 alkoxy, ^cι"^c3 haloalkoxy, amino, ^cι"^C3 alkylamino, ^cι^_C3- acylammo, C-_j_-C₃- alkylsulfonylamino, halogen, nitro, cyano, carboxy, ^C1"^C3 alkoxycarbonyl, sulfonyl, ^cι~^c3" alkylsulfonyl , aminosulfonyl , ^ι^_^3 -alkylaminosulfonyl , trifluoromethyl , for use as antitumor agents.

The present invention also relates to the compounds of formula (I), with the proviso that:

- when R-_j_ and X are hydrogen and R is methyl,^' the group -0-R₂ is not 5-hydroxy, 5-methoxy, 6-methoxy, 7-methoxy, or 3- [ (1 , 1-dimethylethyl) amino] -2 -hydroxypropoxy .

C-_|_-Cg Alkyl is preferably methyl, ethyl, n-propyl, isopropyl, isobutyl, in particular me hyl.

Substituted alkyl is preferably 2-hydroxyethyl , 2- aminoethyl, 2 -dimethylaminoethyl , carboxymethyl . c5"^c6 Cycloalkyl is preferably cyclohexyl or cyclopentyl .

Aralkyl is preferably benzyl or phenethyl . Aryl is preferably phenyl, naphthyl or phenyl substituted with one or two substituents selected from ^C1" 6 alkyl, hydroxy, ^cι^_C ₄ alkoxy, ^cι^_C3 haloalkoxy, amino, ^cχ^_c3 alkylamino, Cι^_C₃ acylamino, ^cι~^C3~ alkylsulfonylamino, halogen, nitro, cyano, carboxy, ^cι"^c3 alkoxycarbonyl, sulfonyl, ^ci~^C3~ alkylsulfonyl , aminosulfonyl , C^-C^- alkylaminosulfonyl , trifluoromethyl .

Heteroaryl is preferably furyl , thienyl, imidazolyl, benzothienyl, benzof ryl , pyridyl, indolyl , pyrimidyl , thiazolyl .

Heteroarylalkyl is preferably pyridylmethyl , thienylmethyl, furylmethyl . cl"^c4 ^Alk°^χy is preferably methoxy or ethoxy. C1~^C3 Haloalkoxy is preferably difluoromethoxy, trichloromethoxy, trifluoromethoxy . Halogen is preferably chlorine. cl~^c3 Alkylamino is preferably methylamino, ^Cι^-C3 acylamino is preferably acetylamino, ^cι^_C3~ alkylsulfonylamino is preferably methylsulfonylamino, ^cι~^c3 -alkylsul- fonyl is preferably methylsulfonyl , ^Cι^-C3- alkylaminosul- fonyl is preferably methylaminosulfonyl and dimethylaminosulfonyl .

Examples of preferred compounds of formula (I) are those in which R is C-^-Cg alkyl, R-_j_ is hydrogen, X is hydrogen and R₂ is C-_|_-Cg alkyl, aralkyl or aryl. R₂—0 is preferably at the 5- position of the lH-pyrido [3 , 4 -b] indol- 1-one heterocyclic system, as represented in the following formula (la)

The compounds of formula (I) can be prepared according to the process illustrated in the following Scheme 1. SCHEME 1

The compounds of formula (II) are known or can be prepared according to known methods. They are reacted with phosphorous pentachloride in an aprotic solvent and then with an aminoacetaldehyde derivative, such as 2- dimethylaminoacetaldehyde dimethylacetal , to give compounds of formula (III) which are then cyclized in the presence of acids such as gas HCl in dioxane or trifluoroacetic acid in methylene chloride to compounds of formula (I) .

The compounds of formula (II) can be prepared according to Scheme 2

SCHEME 2

The anilines of formula (IV) are known or can be prepared with known methods. They are transformed into the corresponding phenols of formula (V) by reaction with alkali nitrites m the presence of strong acids followed by hydrolysis with urea and copper (II) salts. Phenols (V) are then reacted with halides of formula R₂Hal wherein Hal is preferably chlorine or bromine, the presence of acid- bmdmg agents, to give the compounds (VI) . The reaction with oxalic acid diesters, particular diethyl oxalate, m the presence of strong bases such as metal hydrides or alkali alkoxides m anhydrous solvents and inert atmosphere, yields the compounds (VII) which are cyclized to doles (VIII) by reduction of the mtro group, for example with zmc acids. The compounds (II) are then obtained from compounds (VIII) by simple hydrolysis of the ester group, optionally after introduction of the substituent Rl with known methods, for example by N- alkylation.

When the groups R, R₁ , R₂ and X contain substituents which interfere with the used reactions, suitable protective groups will be used and then removed according to conventional methods.

An alternative process for the preparation of the compounds of formula (I) comprises the reaction of compounds of formula (I) which at least one of R-_j_ and R₂ is hydrogen, and R is different from hydrogen, with halides of formula R'₂-Hal, m which R'₂ has the same meanings as R₂ except for hydrogen and Hal is preferably chlorine and bromine, in the presence of alkali metal hydrides, hydroxides or alkoxides, such as NaH, KOH, t-BuOK. The reaction is usually carried out m solvents such as DMSO, DMF at temperatures ranging from 0°C to 80°C, preferably 25-50°C.

The compounds of formula (I) wherein R₂ is hydrogen can be obtained, m addition to the process shown in Scheme 1, also by catalytic hydrogenation of compounds of formula (I) which R₂ is arylmethyl , such as benzyl. The reaction is carried out m solvents such as THF, MeOH, or mixtures thereof, the presence of a metal catalyst such as platinum or palladium, generally under atmospheric pressure and at room temperature .

The compounds according to the invention have been pharmacologically tested against four human tumour cell lines: HT 29 (colon carcinoma), PC 3 (prostate carcinoma), H 460M (lung carcinoma) , MCF-7 (breast carcinoma) . Cells were incubated with the tested compound for 144 hours, then cytotoxicity was determined by using the MTT assay (Mosman, T. "Rapid Colorimetric Assay for Cellular Growth and Survival: Application to Proliferation and Cytotoxicity Assay"; J. Immunolog. Methods, (1983), 65, 66; Green, L.M., Rapid Colorimetric Assay for Cell Viability; Application to the Quantitation of Cytotoxic and Growth Inhibitory Lymphokines" , J. Immunol. Methods, (1984), 70, 257-268). The obtained data evidenced that the compounds according to the present invention have remarkable activity against solid tumors, m particular colon and lung tumors.

The compounds of the invention can be administered m doses ranging from 0.01 mg to 1 g / kg body weight daily. A preferred dosage regimen may range from about 1 mg to about 500 mg / kg body weight daily, using such unitary doses as to administer 24 hours from about 70 mg to about 3.5 g of the active substance to a patient weighing about 70 Kg. Such dosage regimen may be adjusted order to obtain a better therapeutical effect. For example, dosages may be adjusted m consideration of the therapeutical conditions of the patient.

The active compounds of the invention can be administered through the oral, intravenous, intramuscular or subcutaneous route.

The compounds of the invention may be administered, according to well-known therapeutical procedures, m combination with other agents used to induce the regression of tumors, m order to synergistically increase the antitumor effects of said compounds. Examples of compounds which can be used m combination w th the compounds of the invention are cisplatm, carboplatm, doxorubicm, topotecan, taxol, taxotere, vmcristme, 5-fluorouracil . The pharmaceutical compositions according to the present invention contain therapeutically effective amounts of at least one compound of the invention mixture with pharmaceutically acceptable excipients.

The oral compositions will generally include an inert diluent or an edible carrier and may be included m gelatin capsules or compressed into tablets. Other forms suitable for oral administration are capsules, pills, elixirs, suspensions or syrups.

The tablets, pills, capsules and similar compositions may contain the following ingredients (m addition to the active substance) : a binder such as a microcrystallme cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose; a disintegrating agent such as alginic acid, primogel, corn starch and the like; a lubricant such as magnesium stearate; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharine or a flavoring agent such as peppermint, methyl salicylate or orange flavor. When the chosen composition is m form of capsules, it may contain m addition a liquid carrier such as a fatty oil. Other compositions may contain other various materials which modify the physical form, such as coating agents (for tablets and pills) such as sugar or shellac. The materials used the preparation of the compositions should be pharmaceutically pure and not toxic at the employed dosages .

For the preparation of pharmaceutical compositions for the parenteral administration, the active ingredient may be incorporated into solutions or suspensions, which may include in addition the following components: a sterile diluent such as water for injection, saline solution, oils, polyethylene glycols, glycerin, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol; antioxidants such as ascorbic acid or sodium bisulphite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for adjusting the solution tonicity such as sodium chloride or dextrose. The parenteral preparation may be included in ampoules, disposable syringes or glass or plastic vials.

The invention is further described by the following examples .

Preparation 1

1) cone. H₂S0₄, H₂0, NaN0₂

2) CuS0₄ • 5H₂0, 10% c. H₂S0₄,Urea

952.0 mg of 6-nitro-2-aminotoluene are suspended in 15 ml of water, then 3 ml of cone. H₂S0₄ and 10 ml of 10% H₂S0₄ are added thereto. When the amine is almost completely dissolved, the solution is cooled to 0°C and added with 561.1 mg (8.132 mmoles) of NaN0₂ dissolved in 4 ml of H₂0. The mixture is stirred for lh30', added with 468.8 mg ⁽1.878 mmoles) of CuS0₄ • 5H₂0 and 364.5 mg (6.070 mmoles) of urea, then heated to 90°C for 2h30' and finally left at room temperature overnight.

The straw-yellow precipitate is filtered and dissolved in 35 ml of 5% NaOH, the residue is filtered and the solution is acidified to acid pH with 5% HCl (36 ml) .

The precipitate is filtered and dried under vacuum, to obtain 680 mg of a pale yellow solid.

The reaction yield is 71%.

δ (ppm) : 7.43 (d, 1H, H3 , J3 ₂ = 7.80 Hz); 7.18 (t, 1H, H₂) ; 7.00 (d, 1H, H-_L , J_{χ 2} = 7.46 Hz); 5.40-4.50 (bs, 1H, OH) ; 2.40 (s, 3H, CH3 ) m.p. : 133-135°C.

Preparation 2

13.41 g (0.0876 mols) of the derivative of Preparation 1 are dissolved in dry DMF (88 ml) in a round-bottom flask under inert argon atmosphere, then added with 12.12 g

(0.0877 mols) of dry K₂C0₃ and kept under stirring at room temperature for 30 minutes. Afterwards, 11.2 ml (0.0943 mols) of benzyl bromide are added heating to 60 °C for 4h. The reaction is monitored by TLC (Hexane/Ethyl acetate

8:2)^".

The inorganic salts are filtered off, washing with DMF

(50 mL) and the solvent is evaporated off to an about 40 ml volume. The resulting oily residue is filtered through silica (packed with Hexane/Ethyl acetate 9:1), to obtain 14.62 g of straw-yellow solid product.

The reaction yield is 68.6%.

¹H-NMR (200 MHz, CDCl₃) δ (ppm) : 7.43.7.08 (m, 8H, R₁ , H₂ , H₃ , hydrogens on Ph) ; 5,14 (s, 2H, CH₂Ph) ; 2.43 (s, 3H, CH₃ ) .

Preparation 3

EtC CCC Et, (CH,) ₃COK

8.47 g (0.0755 mols) of potassium tert-butoxide and 70 ml of diethyl oxalate are mixed a round-bottom flask under inert argon atmosphere, stirring until t-butoxide is dissolved. The yellowish solution is added with 14.62 g (0.060 mols) of the derivative of Preparation 2 and heated at 60°C for 2h.

The reaction is monitored by TLC (Hexane/Ethyl acetate 8:2) . The resulting purple solution is added with 120 ml of ethyl ether and pH is adjusted to neutral with acetic acid (4.4 ml) ; then the mixture is added with water and extracted with ether (80 ml *3) . The organic solution is dried over sodium sulfate and the solvent is evaporated off.

^"The resulting residue is directly used for the subsequent reaction. Preparation 4

21.0 g of the derivative of Preparation 3 are dissolved m 227 ml of 98% acetic ac d in a round-bottom flask, then added with 10.1 ml of H₂0 and heated under reflux. After that, 29.08 g (0.445 mols) of powder zinc are added, stirring for 30 minutes.

The reaction is monitored by TLC (Hexane/Ethyl acetate 8:2) .

The zinc salts are filtered off and washed with ethanol (30 ml *3) and acetic acid (25 ml *2) .

The combined filtered solutions are added with water (250 ml) to precipitate the product, which s filtered and washed w th some water.

The resulting product requires no further purifications .

The reaction yield is 76.6% on the two steps.

δ (ppm) : 8.95 (bs, 1H, HN) ; 7.53-7.33 (m, 6H, K₅ , H on

Ph) ; -7.22 (t, 1H, Hg ) ; 7.03 (d, IE, H_?); 6.57 (d, 1H, H₉); 5.23 (s, 2H, CH₂Ph) ; 4.41 (q, 2H, CK₂ of COOEt); 1.494 (t, 3H, CH₃ of COOEt) . Preparation 5

13.55 g (0.0459 mols) of the derivative of Preparation 4 are dissolved in 68 ml of ethanol in a round-bottom flask, heated to 50°C and added with 2.31 g (0.0578 mols) of NaOH dissolved in 40 ml of distilled water. The mixture is heated to 80-90°C for 2h.

The reaction is monitored by TLC (Hexane/Ethyl acetate 8:2 and CH₂Cl₂/MeOH 9:1).

The reaction mixture is acidified to acid pH with 5% HCl (42.0 ml) and the precipitated acid is filtered.

The resulting whitish solid product requires no further purifications. The reaction yield is quantitative.

Example 1

14.00 g (0.0524 mols) Preparation 5 are dissolved in 88 ml of 1 , 2 -dimethoxyethane in a round-bottom flask under inert argon atmosphere, added with 13.115 (0.0629 mols) of PCl₅ and stirred at room temperature for 3h; then heated to 40°C for lh.

The solvent is evaporated off and the residue is taken up with 30 ml of 1 , 2 -dimethoxyethane and, still under inert atmosphere, cooled to 0°C and added with 19 ml (0.148 mols) of dimethylammoacetaldehyde dimethylacetal dissolved in 100 ml of ethyl ether. The mixture is stirred at 0°C for ten minutes, then allowed .to reach room temperature and left under stirring overnight. The reaction is monitored by TLC (Hexane/Ethyl acetate 1:1 and CH₂Cl₂/MeOH 9:1).

The precipitated product is filtered, thoroughly washing with ether.

The resulting product still contains traces of the starting dimethylaminoacetaldehyde dimethylacetal. However, the product is not subjected to further purifications.

¹H-NMR (300 MHz, CDCl₃) δ (ppm) ; 9.45 (bs, IH, HN) ; 7.51-7.02 (m, 8H, H₅ , H_? , Hg, H on Ph) ; 6.57 (d, IH, H_g) ; 5.22 (s, 2H, CH₂Ph) ; 4.65 (t, IH, H_χ) ; 3.75 (bs, 2H, H₂ ) ; 3.45 (bs, 9H, NCH₃ , OCH3 ) . b)

3.8 ml of dioxane are saturated with gaseous HCl in a round-bottom flask, then heated to 40°C and added with 395 mg (0.991 mmoles) of the derivative obtained in a) .

The mixture is heated at 50°C for 30 minutes, then the resulting product is filtered to obtain 333 mg of a crude which is purified by flash chromatography (eluent Hexane/Ethyl acetate 2:8, to yield 126.2 mg of 5-benzyloxy- 2 -methyl -lH-pyrido [3 , 4-b] indol- 1-one .

The resulting product is further purified by boiling it in MeOH, filtering and washing with ethyl ether. "The reaction yield is 38.7%. m.p. 245-247°C Elemental analysis: Calculated for C₁₉H₁₆N₂0₂ C = 74.98, H = 5.30. N = 9.20 Found: C = 74.11, H = 5.25, N = 9.09

^-H-NMR. (200 MHz, CD₃SOCD₃) δ (ppm) : 11.95 (bs,lH, HN) ; 7.58-6.74 (m, 10H, U-_L , H₂ ,

H₉, H₇, H₈, H on Ph) ; 5.30 (s, 2H, CH₂Ph) ; 3.60 (s, 3H, NCH₃) .

Example 2

Using in the procedures described in Example 1 the suitable indole-2 -carboxylic acids and the suitable 2- aminoacetaldehydes dialkyl acetals, the following 1H- pyrido [3 , 4-b] indol-1-ones are prepared:

5 -benzyloxy-lH-pyrido [3, 4-b] indol- 1-one, m.p. 264-265°C;

5-benzyloxy-2- (2-pyridylmethyl) -lH-pyrido [3 , 4-b] indol- 1- one;

5-benzyloxy-2- (3 -pyridylmethyl) -IH-pyrido [3 , 4-b] indol -1- one ;

5-benzyloxy-2- (4 -pyridylmethyl) -lH-pyrido [3 , 4-b] indol- 1- one;

5-benzyloxy-2-benzyl-lH-pyrido [3 , 4-b] indol -1-one ;

5-benzyloxy-2- (2 -phenylethyl) -IH-pyrido [3 , 4 -b] indol -1-one ; 5 -benzyloxy-2 -phenyl -IH-pyrido [3 , 4-b] indol -1-one ;

5-benzyloxy-2- (3 -chloro-2 -cyanophenyl) -IH-pyrido [3,4- b] indol -1-one ;

5-benzyloxy-2- (3 -fluoro-2 -cyanophenyl) -IH-pyrido [3,4- b] indol -1-one ; 5 -benzyloxy-2- (3 -chloro-5-trifluoromethylpyridyl) -1H- pyrido [3 , 4-b] indol -1-one ;

5-benzyloxy-2- (2 -thienylmethyl ) -lH-pyrido [3 , 4-b] indol -1- one;

5-benzyloxy-2- (2 -hydroxy-3 -methoxybenzyl) -lH-pyrido [3,4- b] indol -1-one ;

5-benzyloxy-2 - (2 -thienyl ) - lH-pyrido [3 , 4-b] indol - 1-one ;

5-benzyloxy-2- (4-methylphenyl) -IH-pyrido [3 , 4-b] indol-1-one;

5- (4 -methoxybenzyloxy) -2 -methyl -lH-pyrido [3 , 4-b] indol-1- one; -methyl -IH-pyrido [3, 4-b] mdol-l-one; m.p. 271-272°C; - (4-chlorobenzyloxy) -2 -methyl -IH-pyrido [3 , 4-b] mdol-l-one ,-- (4-trιfluoromethylbenzyloxy) -2 -methyl -IH-pyrido [3,4-] mdol-l-one; -methoxy-2 -methyl -IH-pyrido [3, 4-b] mdol-l-one; m.p. 284-85°C; -methoxy-lH-pyrιdo [3, 4-b] mdol-l-one; m.p. > 300°C -benzyloxy-2 -methyl -IH-pyrido [3, 4-b] dol-l-one; m.p. 275-76^CC -benzyloxy- IH-pyrido [3, 4-b] mdol-l-one; -methoxy-2 -methyl -IH-pyrido [3, 4-b] mdol-l-one; -methoxy-lH-pyrιdo [3 , 4-b] mdol-l-one; -nιtro-2-methyl-lH-pyπdo [3 , 4-b] mdol-l-one; -mtro- IH -pyrido [3 , 4-b] mdol-l-one; -nιtro-2-methyl-lH-pyrιdo [3, 4-b] mdol-l-one; -nιtro-lH-pyrιdo [3 , 4-b] mdol-l-one; -methylsulfonyl-2-methyl-lH-pyrιdo [3 , 4-b] mdol-l-one;-methylsulfonyl-lH-pyrιdo [3 , 4-b] mdol-l-one; -methyl-2-methyl-lH-pyrιdo [3 , 4-b] mdol-l-one; -methyl -IH-pyrido [3 , 4-b] mdol-l-one ; -trιf luoromethoxy- 2 -methyl -IH-pyrido [3 , 4-b] mdol-l-one;-trιf luoromethoxy- IH-pyrido [3 , 4-b] mdol-l-one; -f luoro-2-methyl-lH-pyrιdo [3 , 4-b] mdol-l-one; -fluoro-lH-pyrιdo [3 , 4-b] mdol-l-one; -chloro-2-methyl-lH-pyrιdo [3 , 4-b] mdol-l-one; -chloro-lH-pyrιdo [3 , 4-b] mdol-l-one; -hydroxy- 2 -methyl -IH-pyrido [3 , 4-b] mdol-l-one; -hydroxy- IH-pyrido [3 , 4-b] mdol-l-one; -methoxy-2 -methyl -IH-pyrido [3 , 4-b] mdol-l-one ; -methoxy-lH-pyrιdo [3 , 4-b] mdol-l-one; , 7-^"dιmethoxy-2-methyl-lH-pyrιdo [3, 4-b] mdol-l-one; , 7-dιmethoxy-lH-pyrιdo [3 , 4-b] mdol-l-one; -methoxy-2 -methyl -IH-pyrido [3 , 4-b] mdol-l-one; -methoxy-lH-pyrιdo [3 , 4-b] mdol-l-one; 6 -bromo-2 -methyl -lH-pyrido [3 , 4-b] indol -1-one ,- 6 -bromo- IH-pyrido [3 , 4-b] indol -1-one ;

6-methoxy-7-benzyloxy-2-methyl-lH-pyrido [3 , 4-b] indol-1-one; IH-pyrido [3, 4-b] indol-1-one, m.p. 273-276°C; 6-methoxy- 7 -benzyloxy- lH-pyrido [3 , 4-b] indol -1-one ; 6-ethyl-2-methyl-lH-pyrido [3 , 4-b] indol-1-one; 6 -ethyl -IH-pyrido [3 , 4-b] indol -1-one. Example 3 A suspension of KOH (87,4 mg) in dry DMF (3 ml), under nitrogen atmosphere, is added with 5-benzyloxy-2 -methyl -1H- pyrido [3, 4-b] indol -1-one of Example 1 (113,4 mg) , then with dry DMSO (1 ml). After 30 minutes, benzyl bromide (0.09 ml) is added. The reaction mixture is stirred at room temperature for 50 minutes, then added with IN HCl (1,6 ml) to neutral pH and partitioned between water and ethyl acetate. The organic phase is dried over anhydrous Na₂S0₄ and evaporated to drynesε . The resulting residue is purified by column chromatography eluting first with n- hexane/ethyl acetate 7/3 and subsequently with n- hexane/ethyl acetate 6/4.

The chromatographic fractions containing the product are combined, concentrated to dryness and the residue is subjected to a second chromatographic purification eluting with n-hexane/ethyl acetate 6/4. The fractions containing the product are pooled, concentrated to dryness and the residue is purified by flash chromatography, eluting with n-hexane/ethyl acetate 7/3. The fractions containing the product are evaporated to obtain a whitish oil which is crystallized from hot ethyl ether, to give 5-benzyloxy-9- benzyl-2-methyl-lH-pyrido [3 , 4-b] indol-1-one as a white soli^"d (40.2 mg) . m.p. 145.5-146.5;

¹H-NMR (DMSO-d6, pp ) : 7.60-7.10 (m, 13 H) ; 6.99 (d, IH, J = 7.1 Hz); 6.83 (d, IH, J = 7.85); 6.07 (s, 2H) ; 5.33 ( S , 2H ) ; 3 . 58 ( s , 3H ) ;

Elemental analyεis:

Calculated for C₂gH₂₂N₂0₂ C = 79.16, H = 5.62, N = 7.10

Found: C = 78.12, H = 5.62, N = 6.95 Example 4

The following products are prepared by using in the procedure of Example 3 the suitable lH-pyrido [3 , 4 -b] indol -

1-ones of Example 1 or 2 and the suitable alkylating agents : 5-benzyloxy-2 , 9 -dimethyl -lH-pyrido [3 , 4-b] indol-1-one, m.p. 185-186°C; ¹H-NMR (DMSO-d6, ppm) : 7.60-7.35 (m, 7H) ; 7.20 (d, IH, J = 8.22 Hz); 6.95 (d, IH, J = 7.10 Hz); 6.83 (d, IH, J = 7.85 Hz); 5.35 (s, 2H) ; 4.22 (ε, 3H) ; 3.56 (ε, 3H) ; Elemental analysis:

Calculated for C₂₀H₁₈N₂O₂ C = 75.45, H = 5.70, N = 8.80 Found: C = 75.15, H = 5.66, N = 8.78

5 -benzyloxy- 9- (2-dimethylaminoethyl) -2 -methyl -IH- pyrido [3 , 4-b] indol -1-one ; 5-benzyloxy-9- (4 -methoxybenzyl ) -2 -methyl -lH-pyrido [3,4- b] indol -1-one ;

5 -benzyloxy- 9- (4 -chlorobenzyl ) -2-methyl-lH-pyrido [3,4- b] indol -1-one ; 5 -benzyloxy- 9- (4-trifluoro ethylbenzyl) -2-methyl-lH- pyrido [3 , 4-b] indol -1-one ;

5-methoxy-2 , 9-dimethyl -IH-pyrido [3 , 4-b] indol-1-one, m.p. 196.5-198°C 1H-NMR (DMSO-d6, ppm): 7.42 (dd, IH, J = 7.85, J = 8.22 Hz); 7.37 (d, IH, J = 7.10 Hz); 7.17 (dd, IH, J = 0.75 Hz, J = 8.24 Hz); 6.99 (d, IH, 7.10 Hz); 6,72 (d, IH, J = 7.85 Hz); 4.20 (s, 3H) ; 3.95 (s, 3H) ; 3.55 (s, 3H) . Elemental analyεiε:

Calculated for C₁₄H₁₄N₂0₂ C = 69.40, H = 5.82, N = 11.56 Found: C = 68.39, H = 5.77, N = 11.32

6-benzyloxy-2 , 9-dimethyl-lH-pyrido [3 , 4-b] indol-1-one ; 6-methoxy-7 -benzyloxy-2 , 9-dimethyl-lH-pyrido [3,4- b] indol -1-one.

Example 5

A solution of 5-benzyloxy-2-methyl-lH-pyrido [3,4- b] indol-1-one of Example 1 (199 mg) in THF/MeOH 3/1 (24 ml) is hydrogenated under atmospheric pressure at room temperature in the presence of 10% palladium on charcoal

(198.2 mg) . After 30 minutes the absorption of hydrogen ceases. The catalyεt is filtered off and washed on the filter with THF (20 ml) . The pooled filtrates are evaporated off under reduced pressure and the residue is dried under vacuum at 30°C for 45' to give 5-hydroxy-2- methyl -IH-pyrido [3 , 4-b] indol -1-one as a grey solid.

¹H-NMR (DMS0-d6, ppm): 11.75 (s, IH) ; 10.05 (s, IH) ; 7.34 (d, IH) ; 7.15 (dd, IH) ; 6.99 (d, IH) ; 6.92 (dd, IH) ;

6.51 (dd, IH) ; 3.61 (s, 3H) .

Example 6

Following the procedure deεcribed in Example 5, the following productε are prepared starting from the suitable benzyloxy- IH-pyrido [3 , 4-b] indol -1-ones of Example 2:

5 -hydroxy- lH-pyrido [3 , 4-b] indol- 1-one ,^■

6 -hydroxy- 2 -methyl -IH-pyrido [3 , 4-b] indol -1-one

6 -hydroxy- IH-pyrido [3 , 4-b] indol -1-one

6-methoxy- 7 -hydroxy-2 -methyl -IH-pyrido [3 , 4-b] indol -1-one ; 6-methoxy- 7 -hydroxy- IH-pyrido [3 , 4-b] indol -1-one .

Example 7

A solution of 5 -hydroxy-2-methyl- IH-pyrido [3 , 4- b] indol-1-one of Example 5 (153.5 mg) in dry DMF (1 ml), stirred under nitrogen atmosphere, is added with K₂C0₃ (154.3 mg) then, after 30 minutes, with methyl iodide (0.19 ml) .^" The reaction mixture is left under stirring at room temperature for 72 hours and subsequently is taken up with

MeOH (2 ml) and concentrated to drynesε under reduced pressure. The residue is partitioned between CH₂Cl₂ (8 ml) and water (2 ml) . The organic phase is separated and the aqueous one is further extracted with CH₂C1₂ (3 x 10 ml) . The combined organic extracts are dried and evaporated to dryness. The resulting residue is purified by flash chromatography eluting with ethyl acetate/n-hexane 8/2.

The chromatographic fractions containing the product are combined. The solvent is evaporated off to obtain a residue which is taken up into ethyl ether and recovered by filtration, to give 5-methoxy-2 , 9-dimethyl-lH-pyrido [3 , 4- b] indol-1-one (42.1 mg) . m.p. 196.5-198°C 1H-NMR Elemental analysiε:

Calculated for C₁₄H₁₄N₂0₂ C = 69.40, H = 5.82, N = 11.56 Found: C = 69.39, H = 5.77, N = 11.32

Example 8

Following the procedure described in Example 7, the following products are prepared starting from the suitable hydroxylH-pyrido [3 , 4-b] indol-1-ones of Example 6: 6-benzyloxy-9-benzyl-2-methyl-lH-pyrido [3 , 4-b] indol-1-one ; 5- (4-bromobenzyloxy) -9- (4-bromobenzyl) -2 -methyl -1H- pyrido [3 , 4-b] indol -1-one ; 6-methoxy- 7 -benzyloxy- 9 -benzyl -lH-pyrido [3 , 4-b] indol -1-one.

Claims

1 . Compounds of formula I

wherein: R is hydrogen; C-_]_-Cg alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; ^C ₅-Cg cycloalkyl; aralkyl; heteroalkyl; aryl; heteroaryl;

R._j_, is hydrogen; C-^Cg alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; ^C5"^c cycloalkyl; aralkyl; heteroalkyl ;

R₂ is hydrogen; -^-Cg alkyl optionally substituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; C₅-C₈ cycloalkyl; aralkyl; aryl; heteroaryl; heteroarylalkyl ; C-_j_-Cg acyl;

X is one or more groups independently selected from hydrogen, ^cι"^C6 alkyl, hydroxy, C-_j_-C₄ alkoxy, ^cι^_c3 haloalkoxy, amino, ^cι" 3 alkylamino, ^C ₁-C₃- acylamino, ^cι~^c3" alkylsulfonylamino, halogen, nitro, cyano, carboxy, 1"C^~3 alkoxycarbonyl, sulfonyl, ^cι"^C3~ alkylεulfonyl , aminoεulfonyl,

-alkylaminosulfonyl , trifluoromethyl ; with the proviso that:

- when R and X are hydrogen and R is methyl, the group -0-R₂ is not 5-hydroxy, 5-methoxy, 6-methoxy, 7-methoxy, or 3- [ (1, 1-dimethylethyl) amino] -2-hydroxypropoxy .

2. Compounds of formula I

wherein:

R iε hydrogen; C-_j_-Cg alkyl optionally εubstituted with one or more primary, εecondary or tertiary amino groupε, hydroxy or carboxy groups; ^C ₅-Cg cycloalkyl; aralkyl; heteroalkyl; aryl; heteroaryl; R_1; iε hydrogen; ₁-C₈ alkyl optionally subεtituted with one or more primary, secondary or tertiary amino groups, hydroxy or carboxy groups; ^C ₅-Cg cycloalkyl; aralkyl; heteroalkyl ; R is hydrogen; ₁-Cg alkyl optionally subεtituted with one or more primary, εecondary or tertiary amino groupε, hydroxy or carboxy groupε; C₅-C₈ cycloalkyl; aralkyl; aryl; heteroaryl; heteroarylalkyl ; C-^Cg acyl;

X is one or more groups independently selected from hydrogen, ^C ₁-Cg alkyl, hydroxy, ^C ₁-C₄ alkoxy, C₁-C₃ haloalkoxy, amino, ^cι^_C3 alkylamino, ^C ₁-C₃- acylamino, C₁-C - alkylsulfonylamino, halogen, nitro, cyano, carboxy, ^C1"^C3 alkoxycarbonyl, sulfonyl, C_η-C₃- alkylsulfonyl , aminosulfonyl , C₁-C₃ -alkylaminosulfonyl , trifluoromethyl ; aε antitumor agents.

3. Compoundε as claimed in claim 1 or 2 , wherein the OR₂ group is at the 5- poεition of the IH-pyrido [3 , 4-b] indol-1- one heterocyclic εystem.

4. Compoundε as claimed in claim 1 or 2 , wherein R is ^cι"^c6 alkyl' ^Rι ^is hydrogen, X is hydrogen and R₂ is C₁-Cg alkyl , aralkyl or aryl .

5. Pharmaceutical compositions containing as active ingredient a compound of claims 1 - 4 in mixture with a suitable carrier.

6. Compoεitionε as claimed in claim 5, in the form of combined preparations for the sequential or simultaneous administration, containing, in addition to a compound of claims 1 - 4, an antitumor drug with synergistic action.

7. The use of the compounds of claims 1 - 4 for the preparation of medicaments with antitumor activity.