合成路线1

Naratriptan can be obtained by several related ways: 1) The reaction of 5-bromoindole (I) with 1-methylpiperidin-4-one (II) by means of KOH in methylated spirit (or methanol) at room temperature gives 5-bromo-3-(4-(hydroxy-1-methylpiperidin-4-yl)-1H-indole (III) (1, 2), which is condensed with N-methylvinylsulfonamide (IV) by means of palladium acetate and tri-p-tolyl phosphine in hot (110 C) DMF to afford (E)-N-methyl-2-[3-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-1H-indol-5-yl]vinylsulfonamide (V). Finally, this compound is hydrogenated with H2 over Pd/C in DMF/water/HCl, DMF/water/methanol/HCl, or water/methanesulfonic acid. 2) The reaction of indole (I) with piperidone (II) or with 4-hydroxy-1-methylpiperidine (VI) by means of KOH in refluxing methylated spirit or 1-propanol gives 5-bromo-3-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-1H-indole (VII), which is then condensed with N-methylvinylsufonamide (IV) as before, yielding the substituted sulfonamide (V), already obtained. 3) The hydrogenation of the tetrahydropyridine (VII) with H2 over PtO2 in methanol/HCl gives 5-bromo-3-(1-methylpiperidin-4-yl)-1H-indole (VIII), which is finally condensed with N-methylvinylsulfonamide (IV) as before yielding N-methyl-2-[3-(1-methylpiperidin-4-yl)-1H-indol-5-yl]vinylsulfonamide (XI). Finally, this compound is hydrogenated with H2 over Pd/C in ethanol/DMF/HCl. 4) The reaction of 5-bromoindole (I) with sulfonamide (IV) by means of palladium acetate as before gives 2-(1H-indol-3-yl)-N-methylvinylsulfonamide (IX), which is condensed with piperidone (II) by means of refluxing KOH as before, yielding the substituted tetrahydropyridine (V), already obtained. 5) The condensation of sulfonamide (IX) with piperidone (II), by means of KOH at room temperature as before gives N-methyl-2-[3-(4-hydroxy-1-methylpiperidin-4-yl)-1H-indol-3-yl] vinylsulfonamide (X), which is dehydrated to tetrahydropyridine (V) with KOH in refluxing methylated spirit. 6) The cyclization of 2-(4-hydrazinophenyl)-N-methylethanesulfonamide (XII) with 2-(1-methylpiperidin-4-yl)acetaldehyde (XIII) by means of HCl in water. 7) The reaction of 2-(1H-indol-5-yl)-N-methylethanesulfonamide (XIV) with piperidone (II) by means of KOH in refluxing methanol, yielding N-methyl-2-[3-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-1H-indol-5-yl] ethylsulfonamide (XV), which is finally hydrogenated with H2 over Pd/C in ethanol/DMF.

合成路线2

The reaction of N-(benzyloxycarbonyl)-D-proline (I) with oxalyl chloride in dichloromethane/DMF gives the corresponding acyl chloride (II), which is condensed with 5-bromoindole (III) by means of ethylmagnesium bromide in ether yielding 3-(N-benzyloxycarbonyl-D-prolyl)-5-bromoindole (IV). The reduction of the carbonyl group of (IV) with LiAlH4 in THF affords 5-bromo-3-[1-methylpyrrolidin-2(R)-ylmethyl]indole (V), which is condensed with phenyl(vinyl)sulfone (VI) by means of tri-p-tolylphosphine, palladium acetate and triethylamine in refluxing acetonitrile giving the substituted (E)-vinyl sulfone (VII). Finally, this compound is hydrogenated with H2 over Pd/C in ethanol/HCl.

合成路线3

Condensation of 5-bromoindole (I) with oxalyl chloride produced (5-bromo-3-indolyl)glyoxyl chloride (II), which was subsequently treated with dimethylamine to give amide (III). Conversion of (III) to the tributylstannyl derivative (IV) was achieved by reaction with hexabutylditin in the presence of tetrakis(triphenylphosphine) palladium in refluxing dimethoxyethane. Palladium-catalyzed coupling of stannyl indole (IV) with 5-bromo-2-thiophenecarboxaldehyde (V) furnished the thienyl indole (VI). Finally, reduction of (VI) with LiAlH4 in boiling THF produced a mixture of the desired 5-methylthiophene derivative along with the 5-(hydroxymethyl) analogue (VII), that were separated by column chromatography.

合成路线4

Condensation between 5-bromoindole (I) in ether and oxalyl chloride (II) in dichloromethane followed by treatment with dimethylamine provides N,N-dimethyaminoglyoxyl derivative (III), which is then reduced with LiAlH4 in THF to yield compound (IV). Coupling of (IV) with benzoyl chloride (V) by means of Et3N and DMAP in dichloromethane affords benzoylindole derivative (VI), which is then subjected to reaction with tributylstannyl derivative (VII) in toluene in the presence of Pd(PPh3)4 to furnish compound (VIII). Treatment of (VIII) with NaOH in refluxing MeOH gives indole (IX), which is converted into the final product by reduction with LiAlH4 in refluxing THF) and treatment with HCl for the formation of the corresponding hydrochloride salt. Alternatively, the target compound can be obtained as follows: treatment of (IV) with KH in ether and tert-butyllithium in pentane followed by reaction with N-methylpiperidinone (X) affords hydroxy derivative (XI), which is finally converted into the desired product.

合成路线5

Protection of 2-bromoethanol (I) upon treatment with 2-methoxypropene (II) gave a mixture of ketals (III) and (IV). This mixture was used for N-alkylation of 5-bromoindole (V) in the presence of KOH to afford, after ketal hydrolysis, 1-(2-hydroxyethyl)-5-bromoindole (VI) (1). Alternatively, compound (VI) was obtained by alkylation of 5-bromoindole (V) with ethylene oxide (VII) in the presence of NaOH in DMSO (2). The hydroxyl group of (VI) was then protected as the silyl ether (VII) by treatment with tert-butyldimethylsilyl chloride. Subsequent lithium-halogen exchange in (VIII) with tert-butyllithium, followed by reaction with bismuth trichloride provided the triindolyl bismuthane (IX) (1, 2). This was oxidized with either benzoyl peroxide (1) or peracetic acid (2) to produce the corresponding di(acyloxy) pentavalent bismuthanes (X).

合成路线6

The reaction of 4-fluorobenzoyl chloride (I) with N,O-dimethylhydroxylamine (II) in pyridine gives the N-methylhydroxamate (III), which is condensed with 5-bromo-1H-indole (IV) by means of KH and t-BuLi yielding the ketone (V). The alkylation of (V) with ethyl iodide and NaH in DMF affords (1-ethylindol-5-yl)(4-fluorophenyl)methanone (VI), which is reduced with NaBH4 in methanol to the corresponding carbinol (VII). Finally, this compound is treated with carbonyl diimidazole in THF.

合成路线7

The methylation of 5-bromo-1H-indole (I) with methyl iodide and NaH in DMSO gives the 1-methyl derivative (II), which is acylated with 4-fluorobenzoyl chloride (III) and AlCl3 in dichloromethane yielding the 3-acyl derivative (IV). The reduction of (IV) with NaBH4 in methanol affords the corresponding carbinol (V), which is finally treated with carbonyl diimidazole (VI) in THF.

合成路线8