合成路线1

The condensation of ethyl acetate (I) with 4-picoline (II) by means of n-butyllithium in THF gives 1-(4-pyridyl)propanone (III), which by reaction with the dimethylacetal of dimethylformamide (IV) in refluxing HMPT is converted into 4-dimethylamino-3-(4-pyridyl)-3-buten-2-one (V). Finally, this compound is cyclized with cyanacetamide (VI) by means of sodium methoxide in refluxing DMF.

合成路线2

Compound can be prepared in several different ways: 1) The condensation of 2-(4-pyridinyl)-3-dimethylaminoacrolein (I) with cyanacetamide (II) by means of sodium methoxide in refluxing methanol gives 1,2-dihydro-5-(4-pyridinyl)-2-oxonicotinonitrile (III), which by hydrolysis with 90% H2SO4 at 100 C is converted into 1,2-dihydro-5-(4-pyridinyl)-2-oxonicotinamide (IV). Finally, this compound is submitted to a Hofmann degradation with Br2 and NaOH in water. 2) Compound (III) can also be obtained by condensation of 2-(4-pyridinyl)-malonodialdehyde (V) with cyanacetamide (II) by means of morpholine and acetic acid in refluxing benzene. 3) The hydrolysis of (III) with refluxing 50% H2SO4 gives 1,2-dihydro-5-(4-pyridinyl)-2-oxonicotinic acid (VI), which by reaction with 90% HNO3 in conc. H2SO4 at 80 C yields 3-nitro-5-(4-pyridinyl)-2(1H)-pyridinone (VII). Finally, this compound is reduced with H2 over Pd/C in DMF. 4) The decarboxylative hydrolysis of (III) with refluxing 80% H2SO4 gives 5-(4-pyridinyl)-2(1H)-pyridinone (VIII), which can be nitrated with conc. HNO3 in H2SO4 at 80 C to give also (VII).

合成路线3

Reduction of 3,5-dichlorobenzoyl chloride (I) with NaBH4 in THF in the presence of N-methyl pyrrolidone (NMP) provides benzyl alcohol derivative (II), which is then treated with tert-butyl dimethylsilyl chloride (TBDMSCl) in DMF in the presence of imidazole and DMAP to furnish protected compound (III). Lithiation of (III) with BuLi (occasionally in the presence of tetramethylethylenediamine) in THF followed by reaction with p-chlorobenzoyl chloride (IV) in THF affords benzophenone derivative (V), which is then deprotected by means of concentrated HCl to yield benzyl alcohol derivative (VI). Conversion of alcohol (VI) into chloride (VII) is then performed by reaction with SOCl2. Next, reaction of (VII) with NaN3 and NaI in refluxing ethanol gives benzylazide derivative (VIII), which is finally converted into the desired product by reaction with cyanoacetamide (IX) and K2CO3 in DMSO.

合成路线4

Alternatively, the target compound can be obtained as follows: Condensation between 2,6-dichloro-4-methylbenzonitrile (X) and 4-chloroiodobenzene (XI) by means of Mg in refluxing ether gives methyleneimine derivative (XII), which is then converted into 4-(4-chlorobenzoyl)-3,5-dichlorotoluene (XIII) by refluxing in dioxane-aqueous phosphate buffer. (Alternatively, compound (XIII) can also be obtained either by condensation of 3,5-dichlorotoluene (XIV) with p-chlorobenzoyl chloride (IV) by means of BuLi in THF or by treatment of 2,6-dichloro-4-methylbenzoic acid (XV) with thionyl chloride (SOCl2) in refluxing DMF to give (XVI), which then reacts with chlorobenzene (XVII) by means of AlCl3 in refluxing CCl4). Bromination of (XIII) is then performed by reaction with N-bromosuccinimide and dibenzoyl peroxide in refluxing benzene to give 4-(4-chlorobenzoyl)-3,5-dichlorobenzyl bromide (XVIII). (Alternatively, (XVIII) can also be synthesized by treatment of the already reported benzophenone derivative (V) with HOAc in THF/H2O followed by reaction with phosphorus tribromide in diethyl ether.) Finally, (XVIII) is converted into the desired compound either by treatment with 5-amino-1,2,3-triazole-4-carboxamide (XIX) by means of NaH in refluxing EtOH or by first reaction of (XVIII) with KN3 in refluxing EtOH to furnish benzyl azide (VIII), followed by reaction with cyanoacetamide (IX) and NaOMe in refluxing EtOH.

合成路线5

The demethylation of 1-(4-methoxyphenyl)acetone (I) by means of AlCl3 gives the corresponding 4-hydroxy compound (III), which is condensed with epichlorohydrin (III), yielding the expected oxiranylmethyl ether (IV). The addition of 1-(2-methoxyphenyl)piperazine (V) to the epoxide ring of (IV) affords the isopropyl alcohol derivative (VI), which is condensed with dimethylformamide dimethylacetal (VII) to afford the dimethylaminobutenone (VIII). Finally, this compound is cyclized with 2-cyanoacetamide (IX) by means of sodium ethoxide, providing the target pyridone.

合成路线6

This compound can be prepared by several different ways: 1) The reaction ot 4-(chloromethyl)pyridine (I) with NaCN in toluene - water gives 4-(cyanomethyl)pyridine (II), which is condensed with methyl acrylate (III) yielding dimethyl 4-cyano 4-(4-pyridyl)pimelate (IV). The hydrolysis and decarboxylation of (IV) atfords 4-(4-pyridyl)pimelic acid (V), which is cyclized by means of potassium tert-butoxide giving 4-(4-pyridyl)cyclohexanone (VI). The acetylation of (VI) with acetic anhydride or acetylimidazole affords 2-acetyl(4-4 pyridyl)cyclohexanone (VII), which is finally cyclized with acetylacetamide (VIII) by means of dimethylamine. 2) The cyclization of (VII) with cyanoacetamide (IX) by means of piperidine gives 4-cyano-1-methyl-7-(4-pyridyl)-5,6,7,8-tetrahydro-3(2H)-isoquinolinone (X), which is finally treated with methyl magnesium iodide in ether. 3) The condensation of 4 bromopyridine (XI) and cyclohexanedione monoethyleneketal (XII) by means of butyllithium in THF gives 4-hydroxy-4-(4-pyridyil)cyclohexanone ethyleneketal (XIII), which is dehydrated by treatment with SOCl2 and then with NaOH to afford 4-(4-pyridyl)-3-cyclohexenone ethyleneketal (XIV). Finally, this compound is hydrolyzed with HCl and reduced with H2 over Pd/C in 0.5 N HCl yielding cyclohexanone (VII), already obtained.

合成路线7

Three related new synthetic routes for E-1020 have been reported: 1) The cyclization of 2-bromoacetaldehyde diethylacetal (I) with 2-aminopyridine-5-carboxylic acid methyl ester (II) by means of HCl in hot water gives imidazo[1,2-a]pyridine-6-carboxylic acid methyl ester (III), which is reduced with dibutylaluminum hydride in dichloromethane to the corresponding aldehyde (IV). The condensation of (IV) with nitroethane (V) by means of butylamine in refluxing ethanol affords 6-(2-nitro-1-propenyl)imidazo[1,2-a]pyridine (VI), which is treated with Fe-FeCl2-HCl in hot ethanol-water to give 1-(imidazo[1,2-a]pyridyl-6-yl)-2-propanone (VII). The condensation of (VII) with dimethylformamide dimethylacetal (VIII) in hot DMF yields 4-(dimethylamino)-3-(imidazo[1,2-a]pyridin-6-yl)-3-buten-2-one (IX), which is finally cyclized with cyanacetamide (X) by means of sodium methoxide in hot DMF. 2) The cyclization of acetal (I) with 2-amino-5-bromopyridine (XI) as before gives 6-bromoimidazo[1,2-a]pyridine (XII), which is condensed with potassium acetylacetonate (XIII) by means of KI and Cu2I2 in hot DMF yielding the adduct (XIV). The cleavage of (XIV) with NaOH and then with HCl gives the propanone (VII), already obtained. 3) The condensation of the bromo derivative (XII) with 3-chloro-2-methylpropene (XV) by means of ethylmagnesium bromide in hot THF gives 6-isobutenylimidazo[1,2-a]pyridine (XVI), which is ozonolyzed with O3 in methanol-water-HCl to yield the propanone (VII), already obtained.

合成路线8

1) The condensation of 6-bromoimidazo[1,2-a]-pyridine (I) with 2-(chloromethyl)propene (II) by means of Mg and ethyl bromide in THF gives 6-(2-methyl-2-propenyl)imidazo[1,2-a]pyridine (III), which is ozonolyzed with O3 yielding 1-(imidazo[1,2-a]-pyridin-6-yl)-2-propanone (IV). The condensation of (IV) with dimethylformamide dimethylketal (V) in hot DMF affords 4-(dimethylamino)-3-(imidazo[1,2-a]-pyridin-6-yl)-3-buten-2-one (IV), which is finally cyclized with 2-cyanoacetamide (VII) by means of sodium methoxide in hot DMF.

合成路线9

2) The condensation of imidazo[1,2-a]pyridine-6-carboxaldehyde (VIII) with nitroethane (IX) by means of butylamine in refluxing ethanol gives 6-(2-nitro-1-propenyl)imidazo[1,2-a]pyridine (X), which is treated with FeCl2 and concentrated HCl in refluxing ethanol to afford propanone (IV), already obtained.

合成路线10

Treatment of ethyl cyanoacetate derivative (I) with cyanoacetamide (II) in EtOH in the presence of NaOEt provides dicyano derivative (III), which is then converted into diimide (IV) by treatment with refluxing sulfuric acid. Alternatively, (IV) can also be obtained by reaction between cyclopentanone (V), cyanoacetamide (II) and piperidine by means of KOH or NaOH in H2O (or H2O/EtOH) to provide mononitrile derivative (VI), which is then refluxed with H2SO4. Double N-alkylation of compound (IV) with chloride (VII) by heating with NaH or alkaline carbonate in DMF yields dialkylated compound (VIII), which is reduced with LiAlH4 or Red-Al in refluxing THF/toluene to furnish the free base (IX). Finally, (IX) is converted into the desired dihydrochloride by treatment with HCl in isopropanol.

合成路线11

9-Amino-20(RS)-camptothecin is obtained as follows: The cyclization of cyanoacetamide (I) with 2-ethoxy-4-oxo-2-pentenoic acid ethyl ester (II) by means of K2CO3 in hot DMF gives the intermediate pyridone (III), which without isolation is cyclized again with methyl acrylate (IV) in the same conditions affording the indolizinone (V). The treatment of (V) with concentrated HCl in refluxing acetic acid gives the indolizinedione (VI), which is treated with ethylene glycol and trimethylsilyl chloride in dichloromethane to yield the ethylene ketal (VII). The carboxylation of (VII) with diethyl carbonate and KH in refluxing toluene affords the acetic ester derivative (VIII), which is alkylated with ethyl iodide and potassium tert-butoxide in anhydrous DME to the corresponding butyric ester derivative (IX). The reductive acetylation of (IX) with H2 over RaNi in acetic anhydride gives the acetamide derivative (X), which is treated with NaNO2 in acetic acid to yield the corresponding N-nitroso compound (XI). Thermal degradation of (XI) in refluxing CCl4 affords the acetoxymethyl compound (XII), which is submitted to a oxidative cyclization with O2 in methanol/K2CO3 to give the tetracyclic ketal (XIII). Hydrolysis of the ketal group of (XIII) with 2N H2SO4 in hot DME yields the tricyclic triketone (XIV), which is further cyclized with 2-amino-6-nitrobenzaldehyde (XV) by heating at 160 C to afford 9-nitro-20(RS)-camptothecin (XVI). Finally, this compound is hydrogenated with H2 over Pd/C in ethanol. The title product can also be obtained by direct cyclization of tricyclic triketone (XIV) with 2,6-diaminobenzaldehyde (XVII) in the same conditions.

合成路线12

5) The condensation of 3-methylbutanal (XIX) with cyanoacetic acid ethyl ester (XXXII) or cyanoacetamide (XXXIII) by means of dipropylamine in refluxing hexane, followed by treatment with refluxing 6N HCl, gives 3-isobutylglutaric acid (XXXIV). This compound is converted into the corresponding anhydride (XXXV) by treatment with refluxing acetic anhydride. The reaction of the anhydride (XXXV) with NH4OH affords the glutaramic amide (XXXVI), which is submitted to optical resolution with (R)-(+)-1-phenylethylamine, yielding the (S)-enantiomer (XXXVII). Finally, this compound is submitted to a Hoffmann degradation with Br2/NaOH.

合成路线13

The partial hydrolysis of malonodinitrile (I) with HCl in ethanol gives 2-cyanoacetamide (II), which is treated with ammonia in ethanol to yield 3,3-diaminopropenenitrile (III). Finally, this compound is cyclized with 2-bromo-1-(2-fluorophenyl)-1-propanone (IV) by means of TEA in ethanol.

合成路线14

The reaction of 3-methoxybenzoylacetone (I) with dimethylformamide dimethylacetal (II) gives the dimethylaminomethylene derivative (III), which is cyclized with 2-cyanoacetamide (IV) by means of sodium ethoxide in ethanol yielding the pyridinone (V). The condensation of (V) with dimethylformamide dimethylacetal (II) affords the dimethylaminovinylpyridinone (VI), which is cyclized by means of ammonium acetate in DMF providing the 1,6-naphthyridine (VII). The hydrolysis of the cyano group of (VII) with NaOH gives the corresponding carboxylic acid (VIII), which is finally cyclized with N-hydroxyacetamidine (IX) by means of carbonydimidazole (CDI).

合成路线15

Knoevenagel condensation of ketone (I) with ethyl cyanoacetate followed by Michael addition of cyanoacetamide to the resulting alpha-cyanocinnamate (IIa-b) yields cyclic imide (III). Hydrolysis and decarboxylation of (III) with H2SO4 gives diacid (IV), which is cyclized by means of hot H2SO4 to provide indanone (V). Treatment of (V) with oxalyl chloride in CH2Cl2 and catalytic DMF followed by addition of EtOH affords ethyl ester (VI), which is then converted into oxime (VII) by means of t-BuONO in Et2O and HCl. Hydrogenolysis of (VII) with H2 over Pd/C in HOAc/HCl provides alpha-amino derivative (VIII). By reacting (VIII) with ethyl oxalyl chloride (A), in CH2Cl2 in presence of Et3N, (IX) was obtained and then cyclized in presence of NH4OAc in refluxing HOAc to yield pyrazino derivative (X). Finally (X) is hydrolyzed with HCl in dioxane.

合成路线16

Condensation of 3-methoxysalicylaldehyde (I) with cyanoacetamide (II) in the presence of piperidine gave rise to the carbamoyl iminochromene (III). Subsequent condensation of (III) with 3,4,5-trimethoxybenzaldehyde furnished the title compound.

合成路线17