WO1997019039A1

WO1997019039A1 - Solid phase synthesis of heterocyclic compounds and combinatorial compound library

Info

Publication number: WO1997019039A1
Application number: PCT/EP1996/004808
Authority: WO
Inventors: Andreas Marzinzik; Eduard Felder
Original assignee: Novartis Ag
Priority date: 1995-11-17
Filing date: 1996-11-05
Publication date: 1997-05-29
Also published as: AU7564296A

Abstract

Here we report a study on a reaction sequence on solid phase, suitable for the generation of molecular diversity on small heterocycles of the pyrazole and isoxazole type. For each reaction, suitable conditions on solid phase were worked out and a variety of reactive agents (building blocks) was utilized in an effort to grasp the system's breadth of applicability. The inventive reaction sequence can be applied, for example, to exploit by the combinatorial approaches of the split and mix concept.

Description

SOLID PHASE SYNTHESIS OF HETEROCYCLIC COMPOUNDS AND COMBINATORIAL COMPOUND LIBRARY

The synthesis of combinatorial compound libraries is rapidly taking on the role of a powerful component within modern lead finding processes that aim at the identification of compounds with novel target activities of interest. In the drug discovery context, the ability to synthesize small organic molecules with high yield on a solid support has a definite strategic relevance. It facilitates the preparation of compound arrays in multiple parallel syntheses and enables the application of combinatorial methods for the synthesis of large libraries suitable for systematic evaluations in biochemical or biological test systems. In view of the expected biostability and bioavailabihty, small organics (e. g. heterocycles) rather than chain-like bioohgomers are more attractive leads for subsequent medicinal chemistry efforts.

Here we report a scope and limitation study on a reaction sequence on solid phase, suitable for the generation of molecular diversity on small heterocycles of the pyrazole and isoxazole type. For each reaction, suitable conditions on solid phase were worked out and a variety of reactive agents (building blocks) was utilized in an effort to grasp the system's breadth of applicability. The inventive reaction sequence can be applied, for example, to exploit by the combinatorial approaches of the split and mix concept. Surprisingly, using the inventive method a new facile way for the synthesis of combinatorial compound libraries consisting of modified heterocyclic rings in high yields and purity is provided. These combinatorial compound libraries serve as valuable reservoirs for the screening for pharmaceutically active compounds.

Detailed description of the invention

The current invention concerns a solid phase synthesis of a heterocyclic ring, characterized in that it comprises the following steps:

a) a solid carrier having reactive surface groups is loaded directely or via a spacer group with a compound bearing an acetyl function,

b) said acetyl function is modified using the Claisen condensation,

c) optional the reaction product of step b) is modified with an α-alkylation step, and d) the heterocyclic ring is closed using a compound comprising two nucleophiles, wherein at least one of said nucleophiles is NH₂.

In a preferred embodiment of the invention step a) is of formula 1

wherein

Z is a solid carrier;

R¹ is a substituted or unsubstituted conjugated system that has no acidic hydrogen atoms; and

R⁵ is hydrogen, C₁-C₆alkyl, C₁-C₆alkylaryl, C₁-C₆alkoxy-C₁-C₆alkyl, C₁-C₆alkoxycarbonyl- C₁-C₆alkyl; each of which may be substituted or unsubstituted; step b) is of formula 2

wherein

Z, R¹ and R⁵ are defined as above;

R² is substituted or unsubstituted C₁ -C₆alkyl, or a substituted or unsubstituted aromatic or aliphatic ring; and

R⁴ is C₁ -C₆alkyl, preferred is methyl and ethyl; the optional step c) is of formula 3

wherein

Z, R¹, R² and R⁴ are defined as above;

R⁵ is hydrogen

X is a halogen, preferred is I, Br or Cl; and

R³ is C₁-C₆alkyl, C₁-C₆alkenyl, C₁-C₆alkylcarbonyl-C₁-C₆alkylene, arylcarbonyl-C₁- C₆alkylene, or a substituted or unsubstituted aromatic or aliphatic ring; and step d) is of formula 4

wherein

Z, X, R¹, R², R³, R⁴ and R⁵ are defined as above,

Y is a nucleophilic center like NH, NC₁-C₄alkyl, Naryl and O; preferred are O, NH, NC₁- C₄alkyl, NC₁-C₄alkyl aryl, Naryl unsubstituted or substituted with up to four Br, Cl, I, F, C₁- C₄alkyl, NO₂, SO₂C₁-C₄alkyl, OC₁-Calkyl, carboxy or carbonyl groups, suitable aryl groups are for example thienylene, thiantrenylene, furylene, phenoxanthiinylene, isobenzofuranylene, pyrazolylene, isothiazolylene, isoxazolylene, pyridinylene pyrazinylene, pyrimidylene, indolizinylene, indazolylene, isoquinolylene, quinolylene phthalazinylene, naphthyridinylene, quinoxalinylene, quinazolylene, cinnolinylene, phenylene, naphthylene,

with the proviso that either R³ or R⁵ is hydrogen.

In a preferred embodiment of the invention the solid carrier Z is a resin. Usually Z is a particle that is insoluble in the reaction media and to which the ligand can be bound in sufficient amount by means of reactive groups at the surface of the this particle.

The binding of ligand and tag is effected, e.g. by amino, carboxyl, hydroxyl or halogen groups. These reactive groups are usually already constituents of the solid carrier, but they can also be applied or modified subsequently. The solid carrier customarily employed in solid-phase synthesis can be used, for example those used in Merrifield peptide synthesis. They consist largely of a polystyrene molecule that is crosslinked by copolymerization with divinyl benzene. The molecules are additionally derivatised to attach the reactants in the solid-phase synthesis.

In a more preferred embodiment of the invention R¹ is ethinylene, thienylene, thiantrenylene, furylene, phenoxanthiinylene, isobenzofuranylene, pyrazolylene, isothiazolylene, isoxazolylene, pyridinylene, pyrazinylene, pyrimidylene, indolizinylene, indazolylene, isoquinolylene, quinolylene, phthalazinylene, naphthyridinylene, quinoxalinylene, quinazolyl

ene, cinnolinylene, phenylene, naphthylene,

,

,or

; wherein these conjugated systems are unsubstituted or substituted by groups that have no acidic hydrogens. Suitable groups are, for example, Cl, Br, I, CN, phenyl and pyridyl-groups. Especially preferred R¹ are benzene, , and

A preferred R² is, for example ethinyl, thienyl, thiantrenyl, furyl, phenoxanthiinyl, isobenzo- furanyl, pyrazolyl, isothiazolyl, isoxazolyl, pyridinyl, pyrazinyl, pyrimidyl, indolizinyl, indazolyl, isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolyl, cinnolinyl, phenyl and naphthyl; wherein these conjugated systems are unsubstituted or substituted by groups that have no acidic hydrogens. Especially preferred is phenyl, 4-CH₃OC₆H₄, 4-ClC₆H₃(2CI), 4-CH₃OOCC₆H₄, 4-NCC₆H₄, furyl, pyrrolyl, thienyl, pyridyl, methyl pyrridyl, pyrazinyl, C₆H₅COOCH₃, C₆F₅, C₆H₄C(CH₃)₃, C₆H₄OCF₃, C₆H₄OCH₂C₆H₅, C₆H₄O,(CH₂)₁₅CH₃, C₆H₃(CF₃)_2, C₆H₄O(CH₂)₃CH₃, C₆H₄CI, C₆H₄CN, naphthyl, C₆H₄N(CH₃)₂, C₆H₄C₆H₅, C₆H₄OCH₃, C₆H₄C₆H₄COOCH₃, C₆H₂(OCH₃)₃, C₆H₃Cl₂,

A preferred R³ is, for example, hydrogen, C₁-C₆alkyl, C₁-C₄alkoxy-C₁-C₄alkyl, C₁-C₆alkenyl, C₁-C₄alkoxy-aryl, C₁-C₅alkanoyloxy-C₁-C₆alkyl, C₁-C₆alkoxycarbonyl-C₁-C₅alkyl. Especially preferred is hydrogen, ethyl, NCCH₂, CH₃CH₂OOCCH₂, C₆H₅COCH₂ and CH₂=CHCH₂.

The inventive solid phase synthesis can be used for the generation of combinatorial compound libraries, e.g., in a the split and mix concept (Furka et al., Abstr. 14th Int. Congr. Biochem., Prague (1988), 5, 47; Furka et al., Int. J. Peptide Protein Res. (1991), 37, 487).

For example, in the first step the solid support is loaded with the R¹ component bearing the acetyl function (see table 1). Its carbonyl group is activated by standard methods and anchored to the acid labile Rink amide linker on polystyrene (Rink, Tetrahedron Lett. (1987), 28, 3787). We observe quantitative transformations within 1 hour, unless ortho substituted bifunctional derivatives like o-acetophenone and acetylphthalanilidic acid are used, which undergo ring closure side reactions (Nishio et al., Heterocycl. Chem. (1995), 32, 883).

For the Claisen condensation, optimization of the reaction protocol with the prototypic aromatic ester ethyl benzoate identified conditions, which ensure that also deactivated benzoates and heteroaromatic carboxylic esters condense without appreciable formation of side products (see table 2). As expected, carboxylic esters with α-hydrogens (2g) are unsuited, and also weakly acidic heteroaromatic compounds (2k) cannot be applied. The same is the case for nitro derivatives which are prone to reduction. Noticeably, the series of successful conversions to the diketone included a deactivated ester (2b), as well as a bifunctional building block and a component with an additional electrophilic center (2e and 2f resp.).

With regards to the α-alkylation step, we obtain best results in the presence of TBAF, which has the function to shield the oxygen atoms of the β-dicarbonyl intermediate, hence inhibiting O-alkylation as a side reaction and furthermore increasing the nucleophilicity of the compound. Water traces are detrimental to the yield, which otherwise lies around 90% of the C-monoalkylated product. To expand the diversity, alkylating agents other than the simple alkyl iodides described in analogous solution chemistry can be used (Clark et al., J. Chem Soc, Perkin Trans. I (1977), 1743). Ethyl bromoacetate and allyl bromide react without side reactions. With iodoacetonitrile 35% of starting material is observed and bromoacetophenone does not convert cleanly. The failure with benzyl bromide is rather unexpected. The alkylation step is incompatible with the presence of acid or basic heteroaromatic R¹ and R² residues: with the phenyl pyridine diketone 2j several side products are observed upon alkylation with all the listed alkylating agents. Naturally, dispensing with the alkylation altogether enables to broaden the choice of building blocks for the previous Claisen condensation by allowing e.g. the inclusion of N-heterocyclic esters as an alternative source of diversity.

Ring closure to form a heterocyclic scaffold is tested successfully with hydrazines 4a-d and hydroxylamine (5a) (see table 4). With the non-alkylated intermediate 2a a faster cyclization kinetics than with 3a is observed. N-mono-substituted reagents are expected to yield regioisomers with equal efficiency, unless the intermediates would bear large differences of steric and electronic properties at the R¹ and R² sites. During the validation process we isolate both regioisomers of model compound 4d. In this instance we intentionally explore the limits by choosing a difficult case, since hydralazine (for electronic and stenc reasons) is predicted to have a relatively weak tendency to cyclize In fact, after 1 day, only traces of the regioisomers 4d are detectable, and it takes 4 days to obtain a level of 20 % conversion, in the presence of the unsubstituted analog 4a originating from the far more reactive impurity 2a (the non-alkylated diketone precursor).

The collected data on the conversion rates of a variety of reactants within our proposed synthetic scheme provide an information basis sufficient for the planning of combinatorial libraries along different lines of strategies. Decisions can be made on which types of building blocks to include for diversity generation and whether to skip a reaction step in favor of a broader choice of compatible residues or simplified reaction conditions . Moreover, the general utility of the approach could be exploited to form additional ring types (e.g pyrimidines from amidines see formula 5) if the diketone intermediates were subjected to cyclization with other reagents bearing two nucleophilic centers.

General method for the synthesis:

a) Loading of a solid carrier with an acetyl function

4-(2',4'-Dimethoxyphenyl-fmoc-aminomethyl)phenoxy resin (Rink amide resin) is subjected to repeated ishes with 20% piperidine/DMF until no UV absorption from Fmoc is detected in the eluate. b) Coupling procedure:

The NH2-linker group is acylated with 0.3 M-solution of acetyl carboxylic acid (3 eq) at RT (preactivation 40 min with 3.3 eq DICD and 3.3 eq HOBt) until the Kaiser test (Kaiser et al., Anal. Biochem. (1970), 34, 595) is negative. c) Claisen condensation

50 mg (22.5 μmol) of the modified resin are suspended in a solution of 675 μmol carboxylic ester in 670 μl DMA. Under inert gas 18 mg (450 μmol) of sodium hydride (60% dispersion in mineral oil) is added and the reaction mixture is well shaken for 1h at 90 °C. The resin is filtered, ished (30% v/v acetic acid / H₂O, DMA, DMSO, and i-propanole), and dried under reduced pressure. d) α-Alkylation step (if necessary)

20 mg (8.6 μmol) of this modified resin is treated with 86 μl 1M TBAF in THF for 2h at room temperature. After addition of 150 μl of a 2.5 M solution of the appropriate alkylating agent, the reaction is continued for another 2 h. The resin is filtered off and ished well with CH₂Cl₂ and THF. e) Ring closure

The resin resulting from these modifications is heated with 500 μl of a 2.5 M solution of hydrazine derivatives or hydroxyl amine (HCl is neutralized by N(CH₃CH₂)₃) in DMA for 24 h at 80°C. f) Release of the compound from the solid carrier

Cleavage from the support is done by with 20% v/v TFA/CH₂Cl₂ (Rink, Tetrahedron Lett (1987), 28, 3787).

A suitable method for the preparation of a combinatorial compound library comprises, for example, the reaction steps as described above, wherein optionally before a reaction step is carried out,

a) the resin pool is divided into different portions,

b) said reaction step is carried out in each portion using a different chemical compound or reaction, and

c) the portions are mixed together.

Alos embraced by the scope of the current invention is the combinatorial compound library obtainable by the method described above. In order to synthesize a combinatorial compound library, e.g. according to Houghten et al. Nature (1991) 354, 84-86; a solid carrier having reactive surface groups is loaded with a compound bearing an acetyl function; or the resin is divided first into several portions then loaded with a different compound bearing an acetyl function in each portion and mixed again. Afterwards, e.g. , the pool containing the modified resin is divided into several separate portions again. The Claisen condensation is carried out in each portion using a different reagent to get different compounds. These separated pools are mixed and, if appropriate, divided again into several separate portions in which the optional α-alkylation step using different reagents is carried out and, afterwards, the separated pools are mixed again. If desired, the mixture may be divided into several separate portions again for carrying out the ring closure with a different agent in each portion. After mixing, a combinatorial compound library has been created that is suitable, e.g., for screening.

Abbreviations

Examples

The products that are produced in each step are analyzed after cleavage from the solid carrier by the following method:

Cleavage from the support is done by with 20% v/v TFA/CH₂Cl₂ (Rink, Tetrahedron Lett. (1987), 28, 3787).

HPLC analytical separation is achieved using a reverse phase nucleosil C18 5μ 250 mm × 4.6 mm column, 215 nm, 10-90% CH₃CN / 0.1% TFA over 30 mm, 1 ml/min. A part of the eluate (split 1 :25) is introduced into a Quattro-BQ mass spectrometer (VG Biotech, Altnncham, England), operating at a source temperature of 60°C and a cone voltage of 50 V, via an electrospray interface (EI). The mass range from 100 to 800 Dalton is scanned in 4 seconds.

Example 1 Loading of the resin with a compound bearing an acetyl function

Deprotection: 4-(2',4'-Dimethoxyphenyl-fmoc-aminomethyl)phenoxy resin (Rink amide resin) is subjected to repeated washes with 20% piperidine/DMF until no UV absorption from Fmoc is detected in the eluate.

Coupling procedure: The NH₂-linker group is acylated with 0.3 M-solution of 3 eq of a compound of formula 6

at RT (preactivation 40 min with 3.3 eq DICD and 3.3 eq HOBt) until the Kaiser test (Kaiser, E. et al. Anal. Biochem. 1970, 34, 595) is negative . The loading of the resin is 424 μmol/g.

Example 2 Alternative loading of the resin

Deprotection 4-(2',4'-Dimethoxyphenyl-fmoc-aminomethyl)phenoxy resin (Rink amide resin) is subjected to repeated washes with 20% piperidine/DMF until no UV absorption from Fmoc is detected in the eluate.

Coupling procedure: The NH₂-linker group is acylated with 0.3 M-solution of 3 eq of a compound of formula 7

at RT (preactivation 40 min with 3.3 eq DICD and 3.3 eq HOBt) until the Kaiser test (Kaiser, E. et al. Anal Biochem 1970, 34, 595) is negative. The loading of the resin is 410 (resin capacity in [μmol/g]). Example 3 : Claisen condensations

50 mg (22.5 μmol) the modified resin of example 1 are suspended in a solution of 675 μmol carboxylic ester in 670 μl DMA (see table 5). Under inert gas 18 mg (450 μmol) of sodium hydride (60%) is added and the reaction mixture is well shaken for 1h at 90 °C. The resin is filtered, ished (30% v/v acetic acid / H₂O, DMA, DMSO, and i-propanole), and dried under reduced pressure.

Example 4 : Heterocyclic compounds with two or three substituents

50 mg (22.5 μmol) modified resin of example 1 are suspended in a solution of 675 μmol methylbenzoate in 670 μl DMA. Under inert gas 18 mg (450 μmol) of sodium hydride (60%) is added and the reaction mixture is well shaken for 1h at 90 °C. The resin is filtered, ished (30% v/v acetic acid / H₂O, DMA, DMSO, and i-PrOH), and dried under reduced pressure to give a compound of formula 9.

This modified resin is heated with 500 μl of a 2.5 M solution of a nucleophile (HCl is neutralized by N(CH₃CH₂)₃) in DMA for 20-24 h (see table 6) to give the desired heterocyclic products (see table 6).

The products have been analyzed using HPLC after cleavage from the resin as described above

Example 5 Heterocyclic compounds with four substituents

50 mg (22.5 μmol) modified resin of example 1 are suspended in a solution of 675 μmol methylbenzoate in 670 μl DMA. Under inert gas 18 mg (450 μmol) of sodium hydride (60%) is added and the reaction mixture is well shaken for 1h at 90 °C. The resin is filtered, ished (30% v/v acetic acid / H₂O, DMA, DMSO, and i-propanole), and dried under reduced pressure. 20 mg (8.6 μmol) of this modified resin is treated with 86 μl 1 M TBAF in THF for 2h at room temperature. After addition of 150 μl of a 2.5 M solution of the appropriate alkylating agent (see table 7), the reaction is continued for another 2 h. The resin is filtered off and ished well with CH₂Cl₂ and THF. Than the modified resin is heated with 500 μl of a 50 % solution of methylhydrazine (HCl is neutralized by N(CH₃CH₂)₃) in ethanol for 16 h at 56°C to give the desired heterocyclic products (see table 7).

The products have been analyzed using HPLC after cleavage from the resin as described above.

Example 6 : Ring closure with compound that has a weak tendency to cyclize

Deprotection 4-(2',4'-Dimethoxyphenyl-aminomethyl)phenoxy resin (Rink amide resin) is subjected to repeated washes with 20% piperidine/DMF until no UV absorption from Fmoc is detected in the eluate.

The NH₂-linker group of 1.50 g 4-(2',4'-Dimethoxyphenyl-fmoc-aminomethyl)phenoxy resin (Rink amide resin) is acylated with a 0.3 M-solution of a compound of formula 10 (3 eq) at RT (after preactivation for 40 mm with 3.3 eq DICD and 3.3 eq HOBt) until the Kaiser test (Kaiser, E. et al. Anal. Biochem 1970, 34, 595) is negative to form a compound of formula 11.

^°

A portion of the product is cleaved from the resin as defined above and analyzed:

100% purity by HPLC, 10.2 min, MS (El) m/z 163 (M⁺).

50 mg (22.5 μmot) of the compound of formula 11 are suspended in a solution of 0.51g (3.4 mmol) C₆H₅COOCH₂CH₃ in 670 μl DMA. Under inert gas 0.14 g (3.4 mmol) NaH (60% dispersion in mineral oil), and 10.5 ml DMA ;and the reaction mixture is well shaken for 1h at 90 °C. The resin is filtered, ished (30% v/v acetic acid / H₂O, DMA, DMSO, and i-propanole), and dried under reduced pressure to get a compound of formula 12.

A portion of the product is cleaved from the resin as defined above and analyzed

95% purity by HPLC, 26.3 mm, MS (El) m/z 267 (M⁺).

20 mg (8.6 μmol) of this resin is treated with 86 μl 1M TBAF in THF for 2h at room temperature. After addition of 150 μl of a 2.5 M of CH₃CH₂l in CH₂Cl₂, the reaction is continued for another 2 h. The resin is filtered off and ished well with CH₂Cl₂ and THF to give a compound of formula 13.

A portion of the product is cleaved from the resin as defined above and analyzed.

75% purity by HPLC, 22.7 min, MS (El) m/z 294 (M⁺). The compounds of formulas 13 is heated for 4 days under reflux with 1.09 g (6 75 mmol) hydralazine and 67 mg (0.67 mmol) acetylacetone in CH₃CH₂OH to form of the two isomeres of formulas 14 and 15.

For analyzation the product is cleaved from the resin with 20% v/v TFA/CH₂Cl₂ as defined above.

HPLC preparative separation is achieved using a reverse phase nucleosil C18 5μ 20 mm ×

250 mm column, 215 nm, 10-90% CH₃CN/0. 1% TFA over 90 mm, 15 ml/mm (10% purity by

HPLC, 25.3 mm for isomer 15 and 26.3 mm for isomer 14) isomer 15: ¹H-NMR (DMSO-d₆) δ 9.72 (s, 1H), 8.29 (m, 1H), 8.11 (m, 4H), 8.02 (d, J = 8.6 Hz, 2H), 7.90 (d, J = 8 6 Hz, 2H) 7.46 (bs, 1H), 7.32 (m, 2H), 7.24 (m, 1H), 2.77 (q, J = 7.4 Hz, 2H), 1.06 (t, J = 7 4 Hz, 3H), MS (El) m/z 420 (M⁺). isomer 14: ¹H-NMR (DMSO-d₆) δ 9.71 (s, 1H), 8 29 (m, 1H), 8.20 (m, 1H), 8.15 (m, 2H), 7.99 (bs, 1H), 7.82 (m, 4H), 7.51 (m, 4H), 7.42 (bs, 1H), 7.31 (d, J = 8 5 Hz, 2H), MS (El) m/z 420 (M⁺). Example 7 : Pyrazole/Isoxazole library

In a first step the acetyl carboxylic acids R^a ₁ to R^a ₄ are coupled to the resin in separate vessels. The four portions are mixed and distributed in 35 vessels, where each portion reacted with a distinct R^c reagent, a carboxylic acid ester. The result is a randomized R^a and a fixed R^c position. The beads are mixed again and divided into 42 equal portions, of which 41 are reacted with monosubstituted hydrazines R^e. We get a pyrazole library with 11480 compounds divided into 41 sublibraries with 280 compounds each. The remaining last portion of the beads is reacted with hydroxylamme to an isoxazole library comprising 280 compounds. The reagents are used are defined below.

Library Synthesis

Coupling of 4 acetyl carboxylic acids to Rink amide resin: Four portions, of Rink amide resin each 0.5 g (208.5 μmol) are treated with 3 eq of a 0.3 M solution of the appropriate carboxylic acid (agent for R^a) which is preactivated with 3.3 eq DICD and HOBt for 40 minutes. After the Kaiser test is negative the four portions are mixed and washed with DMA, DMSO, and i-PrOH and dried under vacuo .

Claisen Condensation: The resin from the former coupling procedure is divided in 35 separate reaction vessels. Under inert gas atmosphere 21 mg (521 μmol) sodium hydride and 782 μmol carboxylic acid ester (agent for R^c)in 770 μl DMA are added to each resin portion (23 4 μmol). The vigorously mixed reaction mixtures are heated 75 mm at 90°C. All portions are mixed and washed with 30 % v/v acetic acid/water, THF, DMA, DMSO, i-PrOH and dried under vacuo.

Cyclization: 1.6 g (640 μmol) are separated in 42 reaction vessels and each resin is treated with 790 μl of a 0.5 M solution of the appropriate monosubstituted hydrazine in DMA (agent for R^e). After heating the reaction mixtures for 3 days at 90°C each portion is washed separately with DMA, DMSO , and i-PrOH.

Cleavage Approx. 1/3 of the library material, i. e . 12.07 mg (5 μmol) resin from each sublibrary are mixed with 300 μl 20 % v/v TFA/CH₂Cl₂ three times for 30 minutes. Then the resin is washed with 300 μl 1 ,2-dichloroethane and 300 μl trifluoroethanol. The solvents are evaporated in a microcentrifuge and the residue is dissolved in 500 μl DMSO .

Claims

1. Solid phase synthesis of a heterocyclic ring, characterized in that it comprises the following steps:

b) said acetyl function is modified using the Claisen condensation,

c) optional the reaction product of step b) is modified with an α-alkylation step, and d) the heterocyclic ring is closed using a compound comprising two nucleophiles, wherein at least one of said nucleophiles is NH_2.

2. Solid phase synthesis according to claim 1 , characterized in that step a) is of formula 1

wherein

Z is a solid carrier,

R⁵ is hydrogen, C₁-C₆alkyl, C₁-C₆alkylaryl, C₁-C₆alkoxy-C₁-C₆alkyl, C₁-C₆alkoxycarbonyl- C₁-C₆alkylene, each of which may be substituted or unsubstituted.

3. Solid phase synthesis according to claim 1 , characterized in that step b) is of formula 2

wherein

Z, R¹ and R⁵ are defined as in claim 2;

R² is substituted or unsubstituted C₁ -C₆alkyl, or a substituted or unsubstituted aromatic or aliphatic ring ; and

R⁴ is C₁-C₆alkyl.

4. Solid phase synthesis according to claim 1 , characterized in that step c) is of formula 3

wherein

Z, R¹, and R² are defined as in claim 3;

R⁵ is hydrogen

X is a halogen; and

R³ is C₁-C₆alkyl, C₁-C₆alkenyl, C₁-C₆alkylcarbonyl-C₁-C₆alkylene, arylcarbonyl-C₁- C₆alkylene, or a substituted or unsubstituted aromatic or aliphatic ring.

5. Solid phase synthesis according to claim 1 , characterized in that step d) is of formula 4

wherein

Z, X, R¹, R², R³, R⁴ and R⁵ are defined as above;

Y is a nucleophilic center;

with the proviso that either R³ or R⁵ is hydrogen.

6. Use of a solid phase synthesis according to claim 1 for the generation of combinatorial compound libraries.

7. Method for the preparation of a combinatorial compound library, which comprises the steps according to claim 1, wherein optionally before a reaction step is carried out, a) the resin pool is divided into different portion,

c) the portions are mixed together.

8. Solid phase synthesis according to claim 1 , characterized in that Z is a resin.

9. Solid phase synthesis according to claim 2, characterized in that R¹ is ethinylene, thienylene, thiantrenylene, furylene, phenoxanthiinylene, isobenzofuranyiene, pyrazolylene, isothiazolylene, isoxazolylene, pyridinylene, pyrazmylene, pyrimidylene, mdolizinylene mdazolylene, isoquinolylene, quinolylene, phthalazinylene, naphthyridinylene quinoxahnylene qumazolylene, cinnolinylene, phenylene, naphthylene,

naphthylene,

,or

; wherein these conjugated systems are unsubstituted or substituted by groups that have no acidic hydrogens.

10. Solid phase synthesis according to claim 3, characterized in that R² is ethmyl, thienyl, thiantrenyl, furyl, phenoxanthnnyl, isobenzofuranyl, pyrazolyl, isothiazolyl, isoxazolyl, pyridinyl, pyrazinyl, pyrimidyl, indolizinyl, indazolyl, isoqumolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolyl, cinnolinyl, phenyl and naphthyl, wherein these conjugated systems are unsubstituted or substituted by groups that have no acidic hydrogens.

11. Solid phase synthesis according to claim 4, characterized in that R³ is hydrogen, C₁-C₆alkyl, C₁-C₄alkoxy-C₁-C₄alkyl, C₁-C₆alkenyl, C₁-C₄alkoxy-aryl, C₁-C₅alkanoyloxy-C₁- C₆alkyl, C₁-C₆alkoxycarbonyl-C₁-C₅alkyl.

12. Solid phase synthesis according to claim 3, characterized in that R⁴ is hydrogen, methyl, ethyl 13. Solid phase synthesis according to claim 4, characterized in that X is I, Br or Cl. 14. Solid phase synthesis according to claim 5, characterized in that Y is O, NH, NC₁-C₄alkyl, NC₁-C₄alkyl aryl, Naryl unsubstituted or substituted with up to four Br, Cl, I, F, C₁-C₄alkyl, NO₂, SO₂C₁-C₄alkyl, OC₁-C₄alkyl, carboxy or carbonyl groups. Solid phase synthesis according to claim 5, characterized in that Y is NH, O, NCH₃, NC₆H₅, NCH₂C₆H₅ NCH₂COOC₂H₅, NC₆H₄CI NC₆H₃Cl₂, NC₆H₄F, NC₆H₃F₂ NC₆HF₄, NC₆H₄Br, NC₆H₄CH₃, NC₆H₃(CH₃)₂, NC₂H₄OH, NC₆H₄OCH₃ NC₆H₃Cl₂, NC₆H₄B

NC₆H₄CF₃, NC₆H₃CIF, NC₆H₁₀, NC₆H₄COOH, NC₆H₃(NO₂)₂, NC₆H₄NO₂, NCF₃, NC(CH₃)₃,

16. Solid phase synthesis according to claim 2, characterized in that Z is a particle that i insoluble in the reaction media and to which the ligand can be bound in sufficient amoun by means of reactive groups at the surface of the this particle. 17. Solid phase synthesis according to claim 2, characterized in that R¹ is benzene,

18. Solid phase synthesis according to claim 3, characterized in that R² is phenyl 4-CH₃OC₆H₄, 4-CIC₆H₃(2CI), 4-CH₃OOCC₆H₄, 4-NCC₆H₄ furyl, pyrrolyl, thienyl, pyridyl methyl pyrridyl, pyrazinyl, C₆H₅COOCH₃, C₆F₆, C₆H₄C(CH₃)₃, C₆H₄OCF₃, C₆H₄OCH₂C₆H₅ C₆H₄O,(CH₂)₁₅CH₃, C₆H₃(CF₃)₂, C₆H₄O(CH₂)₃CH₃, C₆H₄CI, C₆H₄CN, naphthyl C₆H₄N(CH₃)₂, C₆H₄C₆H₅, C₆H₄OCH₃, C₆H₄C₆H₄COOCH₃, C₆H₂(OCH₃)₃, C₆H₃Cl₂,

19. Solid phase synthesis according to claim 4, characterized in that R³ is hydrogen, ethyl, NCCH₂, CH₃CH₂OOCCH₂, C₆H₅COCH₂, CH₂=CHCH_2. 20. Solid phase synthesis according to claim 4, characterized in that R⁴ is hydrogen, methyl, ethyl 21. Solid phase synthesis according to claim 5, characterized in that Y is NH, NCH₃, NC₆H₅,

22. Solid phase synthesis according to claim 2, characterized in that Z is a particle that is insoluble in the reaction media and to which the ligand can be bound in sufficient amount by means of reactive groups at the surface of the this particle. 23. A combinatorial compound library obtainable by a method according to claim 7. 24. Use of the combinatorial compound library according to claim 23 for screening