合成路线1

Reaction of thiophene-2-carboxylic acid (VIII) with oxalyl chloride and PPh3 gives the corresponding acyl chloride (IX), which is condensed with vinyltributylstannane, yielding 1-(2-thienyl)-2-propen-1-one (X). The addition of HCl to the double bond of (X) affords 3-chloro-1-(2-thienyl)-1-propanone (XI), which is reduced with BH3 and the chiral (R)-oxazaborolidine catalyst (XII) in THF to give (S)-3-chloro-1-(2-thienyl)-1-propanol (XIII) (4). Treatment of (XIII) with NaI in acetone affords the (S)-3-iodopropanol derivative (XIV), which is condensed with methylamine in THF to provide (S)-3-(methylamino)-1-(2-thienyl)-1-propanol (XV). Finally, this compound is condensed with 1-fluoronaphthalene (V) by means of NaH in DMA. The Friedel-Crafts condensation of thiophene (XVI) with 3-chloropropionyl chloride (XVII) by means of SnCl4 in benzene gives the previously reported 3-chloro-1-(2-thienyl)-1-propanone (XI), which is reduced with NaBH4 in ethanol to yield the racemic alcohol (XVIII). Optical resolution of (XVIII) performed by means of immobilized CALB (Novozyme 435, Novo-Nordisk A/S) affords the previously reported (S)-alcohol (XIII).

合成路线2

The reaction of thiophene-2-[14C]carboxylic acid (VII) with oxalyl chloride and PPh3 gives the corresponding labeled acyl chloride (VIII), which is condensed with vinyltributylstannane, yielding 1-(2-thienyl)-[1-14C]prop-2-en-1-one (IX). The addition of HCl to the double bond of (IX) affords 3-chloro-1-(2-thienyl)-[1-14C]propan-1-one (X), which is reduced with BH3 and the chiral (R)-oxazaborolidine catalyst (XI) in THF to give (S)-3-chloro-1-(2-thienyl)-[1-14C]propan-1-ol (XII). Treatment of (XII) with NaI in acetone affords the labeled (S)-3-iodopropanol derivative (XIII), which is condensed with methylamine in THF to provide (S)-3-(methylamino)-1-(2-thienyl)-[1-14C]propan-1-ol (XIV). Finally, this compound is condensed with 1-fluoronaphthalene (V) by means of NaH in DMA.

合成路线3

The enantioselective reduction of 3-chloro-1-(2-thienyl)-1-propanone (I) by means of BH3 catalyzed by (R)-1-methyl-3,3-diphenyltetrahydropyrrolo[1,2-c][1,3,2]oxazaborole (II) in THF gives 3-chloro-1-(2-thienyl)propan-1(S)-ol (III), which is treated with methylamine and NaI in acetone/THF to yield (S)-N-methyl-N-[3-(2-thienyl)propyl]amine (IV). Finally, this compound is condensed with 1-fluoronaphthalene (V) by means of NaH in DMA to provide duloxetine. Alternatively, the enantioselective reduction of 3-chloro-1-(2-thienyl)-1-propanone (I) by means of BH3 catalyzed by (S)-1-methyl-3,3-diphenyltetrahydropyrrolo[1,2-c][1,3,2]oxazaborole (VI) in THF gives 3-chloro-1-(2-thienyl)propan-1(R)-ol (VII), which is condensed with 1-naphthol (VIII) by means of DEAD and PPh3 to yield the expected aryl ether (IX), with inversion of the configuration. Finally, this compound is treated with methylamine and NaI in acetone/THF to provide duloxetine.

合成路线4