合成路线1

The isomerization of trans-8-oxo-5-(3,4,5-trimethoxyphenyl)-5,6,7,8-tetrahydronaphtho[2,3-d][1,3]benzodioxole-6-carboxylic acid ethyl ester (XI) with LDA gives the corresponding cis isomer (XII), which is treated with trimethylsilyl triflate yielding the silylated enol ether (XIII). The reaction of (XIII) with benzyloxymethyl chloride and TiCl4 affords the benzyloxymethyl derivative (XIV), which is reduced at the ketonic group with LiBH4 giving the lactone (XV). The debenzylation of (XV) with H2 over Pd/C yields the carbinol (XVI), which is rearranged to the target compound with DCC in acidic medium.

合成路线2

Eprosartan has been obtained by several different ways: 1) The iodination of 2-butylimidazole (I) with I2 and Na2CO3 in dioxane/water gives 2-butyl-4,5-diiodoimidazole (II), which is treated with benzyl chloromethyl ether (III) and K2CO3 in DMF yielding the imidazole derivative (IV). The condensation of (IV) with N-methyl-N-(2-pyridyl)formamide (V) by means of butyllithium in THF affords 1-(benzyloxymethyl)-2-butyl-4-iodoimidazole-5-carbaldehyde (VI), which is deprotected with concentrated HCl ethanol to give 2-butyl-4-iodoimidazole-5-carbaldehyde (VII). The acylation of (VII) with methyl 4-(bromomethyl)benzoate (VIII) by means of K2CO3 in hot DMF yields 4-(2-butyl-5-formyl-4-iodoimidazol-1 ylmethyl)benzoic acid methyl ester (IX), which is deiodinated by hydrogenation with H2 over Pd/C in methanol affording compound (X). The condensation of (X) with methyl 3-(2-thienyl)propionate (XI) by means of lithium diisopropylamide (LDA) in THF gives (XII), which is acylated with acetic anhydride and dimethylaminopyridine (DMAP) in dichloromethane yielding the corresponding acetate (XIII). Elimination of acetic acid from (XIII) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in hot toluene affords the expected propenoic ester (XIV), which is finally saponified with NaOH or KOH in ethanol/water.

合成路线3

The regioselective reaction of cyclopentadiene (I) and sodium or commercial sodium cyclopentadienide (II) with benzyl chloromethyl ether (III) by means of the chiral catalyst (-)-diisopinocampheylborane in THF, followed by hydroxylation with H2O2/NaOH, gives (1S-trans)-2-(benzyloxymethyl)-3-cyclopenten-1-ol (IV), which is regioselectively epoxidized with tert-butyl hydroperoxide and vanadyl acetylacetonate in 2,2,4-trimethylpentane, yielding [1S-(1alpha,2alpha,3beta,5alpha)-2-(benzyloxymethyl)-6-oxabicyclo[3.1.0]hexan-3-ol (V). The protection of (V) with benzyl bromide and NaH affords the corresponding ether (VI), which is condensed with 6-O-benzylguanine (VII) by means of LiH in DMF to give the guanine derivative (VIII). The protection of the amino group of (VIII) with 4-methoxyphenyl(diphenyl)chloromethane (IX), TEA and DMAP in dichloromethane gives intermediate (X), which is oxidized at the free hydroxyl group with methylphosphonic acid, DCC and oxalic acid in DMSO or Dess Martin periodinane in dichloromethane, yielding the cyclopentanone derivative (XI). The reaction of (XI) with (i) Zn/TiCl4/CH2Br2 complex in THF/CH2Cl2, (ii) activated Zn/PbCl2/CH2I2/TiCl4 in THF/CH2Cl2 (2), (iii) Nysted reagent/TiCl4 in THF/CH2Cl2 or (iv) Tebbe reagent in toluene affords the corresponding methylene derivative (XII), which is partially deprotected with 3N HCl in hot THF, providing the dibenzylated compound (XI). Finally, this compound is treated with BCl3 in dichloromethane. (Scheme 18263401a)

合成路线4

The reaction of allyl alcohol (I) with triethyl orthoacetate at 120 C gives the 4-pentenoic ester (II), which is hydrolyzed with KOH to the corresponding free acid (III). The reaction of (III) with (COCl)2 yields the acyl chloride (IV), which is condensed with 4(S)-isopropyloxazolidin-2-one (V) (a chiral auxiliary), by means of BuLi to afford the chiral imide (VI). The diastereoselective alkylation of (VI) with benzyloxymethyl chloride (VII) by means of TiCl4 and TEA in dichloromethane provides the alkylated compound (VIII) with a diastereoselectivity of 70/30% and combined yields of 84%. The reductive elimination of the chiral auxiliary in (VIII) by means of LiAlH4 gives the alcohol (IX), which is treated with Ac2O to yield the acetate (X). The cyclization of (X) by means of I2 and pyridine in acetonitrile affords the chiral tetrahydrofuran (XI)????XI)a, which is condensed with the sodium salt of 1,2,4-triazole (XII) in hot DMF to provide the adduct (XIII). The debenzylation of (XIII) with H2 over Pd/C gives the alcohol (XIV), which is finally treated with Ts-Cl and pyridine to give rise to the target intermediate tosylate (XV) (see scheme no. 20027601a, intermediate no. (II))

合成路线5

The intermediate (R)-formyl amide (IX) was synthesized as follows. Acylation of the lithium anion of (S)-4-benzyl-2-oxazolidinone (I) with valeryl chloride (II) provided acyl oxazolidinone (III). Subsequent diastereoselective benzyloxymethylation of (III) with chloride (IV) and TiCl4 gave benzyl ether (V). Hydrolysis of (V) with lithium peroxide, followed by coupling of the resulting carboxylic acid (VI) with diethylamine in the presence of TBTU yielded diethylamide (VII). Hydrogenolysis of the benzyl group of (VII) using Pearlman's catalyst afforded alcohol (VIII), which was oxidized to aldehyde (IX) by means of Dess-Martin periodinane or NaOCl in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO) to give (IX).

合成路线6