合成路线1

The two enantiomers of amlodipine have been obtained as follows: The reaction of 2-azidoethanol (I) with chloroacetic acid (II) by means of NaH in THF gives 2-(2-azidoethoxy)acetic acid (III), which is condensed with Meldrum's acid (IV) and 3-hydroxypropionitrile (V) in dichloromethane to yield the 2-cyanoethyl acetoacetate (VI). The cyclization of (VI) with 2-chlorobenzaldehyde (VII) and methyl 3-aminocrotonate (VIII) in refluxing ethanol affords the dihydropyridine (IX), which is selectively hydrolyzed at the 2-cyanoethylester with NaOH to give the dihydropyridine monocarboxylic acid (X). The esterification of (X) with (S)-2-methoxy-2-phenylethanol (XI) by means of CDI in dichloromethane provides the ester (XII) as a diastereomeric mixture, which is separated by chromatography to furnish diastereomers (XXI A) and (XII B). The selective ethanolysis of (XII A) and (XII B) with sodium ethoxide in refluxing ethanol/diglyme gives enantiomers (+)-(XIII) and (-)-(XIII), which are finally reduced with H2 over Pd/CaCO3 in ethanol to afford the (-)- and (+)-isomers, respectively, of the target compound.

合成路线2

By cyclocondensation of 3-chloro-6-fluoro-2-(trifluoromethyl)benzaldehyde (I), isopropyl 3-aminocrotonate (II) and methyl 4-fluoroacetylacetate (III) by heating at 110 C. The starting products are prepared as follows: Aldehyde (I) is obtained by reaction of 1-chloro-4-fluoro-3-(trifluoromethyl)benzene (IV) with N-methyl-N-phenylformamide (V) by means of butyllithium in TNF. Aminocrotonate (II) is obtained by reaction of isopropyl acetoacetate (VI) with dry ammonia in methanol. Finally, the acylation of 2,2-dimethyl-1,3-dioxane-4,6-dione (VII) with fluoroacetyl chloride (VIII) by means of pyridine in dichloromethane gives 5-(fluoroacetyl)-2,2-dimethyl-1,3-dioxane-4,6-dione (IX), which is then treated with refluxing methanol to give 4-fluoroacetylacetate (III).

合成路线3

A synthesis of S-12968 has been published: The cyclization of 4-[2-(2-phthalimidoethoxy)ethoxy]-3-oxobutyric acid ethyl ester (I) with 2-(2,3-dichlorobenzylidene)-3-oxobutyric acid 2-cyanoethyl ester (II) and ammonium formate in hot ethanol gives the protected racemic 1,4-dihydropyridine (III), which is submitted to a chiral preparative HPLC to obtain the (R)-(-)-enantiomer (IV). The deprotection of (IV) with aqueous methylamine affords (S)-(-)-2-[2-(2-aminoethoxy)ethoxymethyl]-4-(2,3-dichlorophenyl)-1,4-di hydropyridine-3,5-dicarboxylic acid 3-monoethyl ester (V). Finally, this compound is methylated with diazomethane in ethyl ether/methanol. The starting compound, the dichlorobenzylidene derivative (II) has been obtained as follows: The condensation of Meldrum's acid (X) with acetic acid (XII) by means of CDI and pyridine as before gives 5-acetyl-2,2-dimethyl-1,3-dioxane-4,6-dione (XIII), which is submitted to ring opening with 3-hydroxypropionitrile (XIV) in refluxing toluene yielding 2-cyanoethyl acetoacetate (XV). Finally, the condensation of (XV) with 2,3-dichlorobenzaldehyde (XVI) by means of piperidine and hexanoic acid in refluxing benzene affords the dichlorobenzylidene derivative (II) used as the second starting compound.

合成路线4

The starting compound phthalimido derivative (I) could be obtained as follows: The condensation of 2-[2-(2-chloroethoxy)ethoxy]ethanol (VI) with potassium phthalimide (VII) in refluxing DMF gives the expected phthalimido derivative (VIII), which is oxidized with the Jones reagent in acetone yielding 2-[2-(2-phthalimidoethoxy)ethoxy]acetic acid (IX). The condensation of (IX) with 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid) (X) by means of carbonyldiimidazole (CDI) and pyridine in dichloromethane affords 2,2-dimethyl-5-[2-[2-(2-phthalimidoethoxy)ethoxy]acetyl]-1,3-dioxane-4,6-dione (XI), which is finally treated with refluxing ethanol to obtain the phthalimido derivative (I) used as starting material.

合成路线5

The condensation of phthalic anhydride (I) with glycine (II) by heating at 160 C gives 2-phthalimidoacetic acid (III), which is treated with refluxing SOCl2 to yield the acetyl chloride (IV). The condensation of (IV) with Meldrum's acid (V) by means of pyridine in dichloromethane, followed by a treatment with refluxing ethanol, affords 4-phthalimidoaetoacetic acid ethyl ester (VI), which is condensed with 1-13C-labeled 2-bromoacetic acid ethyl ester (VII) by means of NaH in dimethoxyethane to provide labeled 2-(2-phthalimidoacetyl)succinic acid diethyl ester (VIII). Finally, this compound is treated with HCl in refluxing acetic acid to give the target labeled aminolevulinic acid.

合成路线6

The condensation of phthalic anhydride (I) with 1-13C-labeled glycine (II) by heating at 160 C gives 2-phthalimidoacetic acid (III), which is treated with refluxing SOCl2 to yield the acetyl chloride (IV). The condensation of (IV) with Meldrum's acid (V) by means of pyridine in dichloromethane, followed by a treatment with refluxing ethanol affords 4-phthalimidoaetoacetic acid ethyl ester (VI). This compound is condensed with 2-bromoacetic acid ethyl ester (VII) by means of NaH in dimethoxyethane to provide labeled 2-(2-phthalimidoacetyl)succinic acid diethyl ester (VIII). Finally, the compound is treated with HCl in refluxing acetic acid to give the target labeled aminolevulinic acid.

合成路线7

The condensation of phthalic anhydride (I) with glycine (II) by heating at 160 C gives 2-phthalimidoacetic acid (III), which is treated with refluxing SOCl2 to yield the acetyl chloride (IV). The condensation of (IV) with Meldrum's acid (V) by means of pyridine in dichloromethane, followed by a treatment with refluxing ethanol affords 4-phthalimidoaetoacetic acid ethyl ester (VI). This compound is condensed with 2-13C-labeled 2-bromoacetic acid ethyl ester (VII) by means of NaH in dimethoxyethane to provide labeled 2-(2-phthalimidoacetyl)succinic acid diethyl ester (VIII). Finally, this compound is treated with HCl in refluxing acetic acid to give the target labeled aminolevulinic acid.

合成路线8

The condensation of phthalic anhydride (I) with glycine (II) by heating at 160 C gives 2-phthalimidoacetic acid (III), which is treated with refluxing SOCl2 to yield the acetyl chloride (IV). The condensation of (IV) with 2-13C-labeled Meldrum's acid (V) by means of pyridine in dichloromethane, followed by a treatment with refluxing ethanol affords 4-phthalimidoaetoacetic acid ethyl ester (VI). This compound is condensed with 2-bromoacetic acid ethyl ester (VII) by means of NaH in dimethoxyethane to provide labeled 2-(2-phthalimidoacetyl)succinic acid diethyl ester (VIII). Finally, the ester is treated with HCl in refluxing acetic acid to give the target labeled aminolevulinic acid.

合成路线9

The condensation of 6-chloro-5-methoxy-1H-indole (I) with Meldrum's acid (II) and acetaldehyde (III) catalyzed by L-proline in acetonitrile gives the adduct (IV), which is treated with Cu and ethanol in refluxing pyridine to yield 3-(6-chloro-5-methoxy-1H-indol-3-yl)butyric acid ethyl ester (V). The reaction of (V) with hydrazine at 140 C affords the hydrazide (VI), which is treated with NaNO2 and Ac-OH to provide the corresponding azide that, without isolation, is thermolyzed and rearranged in toluene at 80?C to give 7-chloro-6-methoxy-4-methyl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indol-1-one (VII). The cleavage of the lactam ring of (VII) with KOH in refluxing ethanol/water yields 3-(2-amino-1-methylethyl)-6-chloro-5-methoxy-1H-indole-2-carboxylic acid (VIII). The decarboxylation of (VIII) by means of refluxing aq. 3M HCl affords 3-(2-amino-1-methylethyl)-6-chloro-5-methoxy-1H-indole (IX), which is finally acylated with acetic anhydride and pyridine in toluene to provide the target 6-chloromelatonin as a racemic compound.

合成路线10

Acylation of Meldrum's acid (I) with propionyl chloride (II) in the presence of pyridine gave propionyl derivative (III). Subsequent ring opening of (III) with ethanethiol (IV), followed by decarboxylation provided S-ethyl 3-oxothiovalerate (V). Propyl 3-amino-3-phenyl-2-propenoate (VII) was prepared by reaction of benzoylacetate (VI) with ammonium acetate in refluxing ethanol. Then, Hantzsch condensation of ketothioester (V), beta-enaminoester (VII), and butyraldehyde (VIII) in EtOH at 80 C in a sealed tube furnished the dihydropyridine (IX). Finally, oxidation of (IX) using chloranil (X) in boiling THF gave the target pyridine.

合成路线11

Acylation of Meldrum's acid (I) with propionyl chloride (II) in the presence of pyridine gave propionyl derivative (III). Subsequent ring opening of (III) with ethanethiol (IV), followed by decarboxylation provided S-ethyl 3-oxothiovalerate (V). Ethyl 3-amino-3-phenyl-2-propenoate (VII) was prepared by reaction of benzoylacetate (VI) with ammonium acetate in refluxing ethanol. Then, Hantzsch condensation of ketothioester (V), beta-enaminoester (VII), and propionaldehyde (VIII) in EtOH at 80 C in a sealed tube furnished the dihydropyridine (IX). Finally, oxidation of (IX) using chloranil (X) in boiling THF gave the target pyridine.

合成路线12

Acylation of Meldrum's acid (I) with propionyl chloride (II) in the presence of pyridine gave propionyl derivative (III). Subsequent ring opening of (III) with propanethiol (IV), followed by decarboxylation provided S-propyl 3-oxothiovalerate (V). Propyl 3-amino-3-(m-chlorophenyl)-2-propenoate (VII) was prepared by reaction of (3-chlorobenzoyl)acetate (VI) with ammonium acetate in refluxing ethanol. Then, Hantzsch condensation of ketothioester (V), beta-enaminoester (VII), and propionaldehyde (VIII) in EtOH at 80 C in a sealed tube furnished the dihydropyridine (IX). Finally, oxidation of (IX) using chloranil (X) in boiling THF gave the target pyridine.

合成路线13

Acylation of Meldrum's acid (I) with butyryl chloride (II) in the presence of pyridine gave butyryl derivative (III). Subsequent ring opening of (III) with ethanethiol (IV), followed by decarboxylation provided S-ethyl 3-oxothiocaproate (V). Ethyl 3-amino-3-phenyl-2-propenoate (VII) was prepared by reaction of benzoylacetate (VI) with ammonium acetate in refluxing ethanol. Then, Hantzsch condensation of ketothioester (V), b-enaminoester (VII), and propionaldehyde (VIII) in EtOH at 80 C in a sealed tube furnished the dihydropyridine (IX). Finally, oxidation of (IX) using chloranil (X) in boiling THF gave the target pyridine.

合成路线14

A synthetic route based on the asymmetric reduction of oxo diesters has been reported. Meldrum's acid (LII) was acylated by methyl adipoyl chloride (LI) in the presence of pyridine to produce the intermediate (LIII) which, upon alcoholysis with isobutanol, led to oxo diester (LIV). Enantioselective reduction of (LIV) by means of baker's yeast furnished the (S)-hydroxy diester (LV). Alternatively, the analogous oxo diester (LVI) was prepared by acylation of methyl acetoacetate with methyl adipoyl chloride (LI), followed by deacetylation in the presence of ammonium hydroxide. Then, asymmetric chemical reduction of (LVI) by hydrogenation in the presence of the chiral catalyst Ru2Cl4[(S)-BINAP]2 provided the (S)-hydroxy diester (LVII). Regioselective reduction of either diester (LV) or (LVII) by means of NaBH4 in refluxing THF furnished dihydroxy ester (XLVIII). After conversion of (XLVIII) to the dimesylate (XLIX), displacement with potassium thioacetate afforded the bis(acetylthio) derivative (LVIII), which was further hydrolyzed with KOH to provide dihydrolipoic acid (LIX). In a related procedure, dihydrolipoic acid (LIX) was prepared by reaction of dimesylate (XLIX) with sodium disulfide, followed by reductive treatment with NaBH4 and NaOH. The title cyclic disulfide was then obtained by oxidation of the dithiol (LIX) using oxygen in the presence of FeCl3.

合成路线15

Acylation of Meldrum's acid (I) with 3-tryphenylmethylsulfanyl)propionic acid (II) by means of DCC produces the intermediate adduct (III), which is subsequently reduced to the tritylsulfanyl derivative (IV) by using NaBH4/AcOH. Alkylation of (IV) with methyl 3-bromopropionate (V) in the presence of NaOMe provides the 5,5-disubstituted dioxanedione (VI). Basic hydrolysis of (VI) gives rise to the tricarboxylic acid (VII), which is further decarboxylated to (VIII) in hot DMSO. Finally the S-trityl protecting gropu is removed by treatment with trifluoroacetic acid and triisopropylsilane.

合成路线16

Decarboxylation of methyl 3-aminothiophene-2-carboxylate (I) in 2 N NaOH leads to 3-aminothiophene (II). Meldrum's acid (III) is condensed with triethyl orthoformate to produce the ethoxymethylene derivative (IV). Subsequent reaction of enol ether (IV) with 3-aminothiophene (II) gives rise to enamine (V), which is further cyclized to thienopyridinone (VI) upon heating in dowtherm A at 260 C. This is then chlorinated by means of oxalyl chloride to furnish 4-chlorothieno[3,2-b]pyridine (VII). Metalation of (VII) with butyllithium in cold THF, followed by treatment with I2 affords the aryl iodide (VIII). Palladium-catalyzed coupling of (VIII) with the lithiated derivative of 1-methylimidazole (IX) yields (X). Finally, displacement of the chloride group of (X) with 5-amino-2-methylindole (XI) provides the title compound.

合成路线17

合成路线18

合成路线19

Reaction of 2-aminobenzyl alcohol (I) with acetone in aqueous AcOH affords 2,2-dimethyl-1,4-dihydro-2H-3,1-benzoxazine, which is reduced with LiAlH4 in THF, producing 2-(isopropylamino)benzyl alcohol (II). After oxidation of alcohol (II) to the corresponding benzaldehyde (III) by means of MnO2 in toluene at 117 °C, Knoevenagel condensation with Meldrum’s acid (IV) in the presence of AcOH and ethylenediamine in MeOH gives 1-isopropyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acid (V) . Chlorination of acid (V) with SOCl2 in toluene at 95 °C and subsequent coupling of the resulting acid chloride with N-Boc-endo-3-aminotropane (VI) in the presence of NaOH in toluene/water affords the corresponding amide (VII). Deprotection of the N-Boc-tropane derivative (VII) by means of TFA in CH2Cl2 furnishes the corresponding amine TFA salt (VIII) (1-9), which is then N-alkylated with 1-chloro-3-(N-Boc-N-methylamino)propan-2(S)-ol (IX) [prepared by condensation of (S)-epichlorohydrin (X) with Nmethylbenzylamine in hexane and subsequent hydrogenolysis of the obtained benzylamine derivative (XI) in the presence of Pd(OH)2/C and Boc2O in EtOAc] in the presence of DIEA in MeOH at 80 °C to give the N-Boc-methylamine derivative (XII). Deprotection of this compound by means of TFA in CH2Cl2 and N-sulfonylation of the obtained free amine (XIII) with methanesulfonyl chloride (XIV) in the presence of DBU in CH2Cl2 then affords velusetrag. Alternatively, reaction of amine (VIII) with N-[(S)-glycidyl]-N-methylmethanesulfonamide (XV) [prepared by alkylation of N-methylmethanesulfonamide (XVI) with (S)-epichlorohydrin (XVII) using aqueous NaOH] in the presence of NaOH in MeOH yields velusetrag . N-Boc-endo-3-aminotropane (VI) is prepared by hydrolysis of 2,5-dimethoxytetrahydrofuran (XVIII) with aqueous HCl, followed by Mannich reaction of the resulting succinaldehyde with BnNH2 and 1,3-acetonedicarboxylic acid (XIX) in the presence of HCl in H2O to give N-benzyl-8-azabicyclo[3.2.1]octan-3-one (XX). Treatment of this compound with H2 over Pd(OH)2/C and Boc2O in EtOAc yields N-Boc-8-azabicyclo[3.2.1]octan-3-one (XXI), which is then converted to the desired amine (VI) by reductive amination with HCOONH4 in the presence of Pd/C in MeOH/H2O .
Velusetrag can be converted to its salts, including hydrochloride, citrate,adipate, phosphate, sulfate, tartrate, malate, hydrobromide and mesylate, by treatment with the respective acids .