The condensation of 4-fluorophenacyl chloride (I) with N-isopropylaniline gives N-(4-fluorobenzoylmethyl)-N-isopropylaniline (II), which is cyclized in a conventional way to 3-(4-fluorophenyl)-1-isopropyl-indole (III) and condensed with 3-(dimethylamino)acrolein (IV) by means of POCl3 in refluxing acetonitrile, yielding 3-[3-(4-fluorophenyl)-1-isopropyl-indol-2-yl]acrolein (V). The condensation of (V) with methylacetoacetate (VI) by means of NaH and butyl-lithium in THF affords methyl 7-[3-(4-fluorophenyl)-1-isopropyl-1H-indol-2-yl]-5-hydroxy-3-oxo-6-heptenoate (VII), which is reduced with triethylborane and NaBH4 in THF, giving the dihydroxy ester (VIII). Finally, this compound is hydrolyzed with NaOH in ethanol.
The condensation of 3-(4-fluorophenyl)-2-(hydroxymethyl)-1-isopropyl-1H-indole (IX) with trimethyl phosphite by means of oxalyl chloride in toluene gives 3-(4-fluorophenyl)-1-isopropyl-1H-indol-2-ylmethylphosphonic acid dimethyl ester (X), which is condensed with erythro-3,5-di(tert-butyldiphenylsilyloxy)-6-oxohexanoic acid allyl ester (XI) by means of butyllithium in THF yielding erythro-3,5-di(tert-butyldiphenylsilyloxy)-7-[3-(4-fluorophenyl)-1H-indol-2-yl]-6(E)-heptenoic acid allyl ester (XII). The hydrolysis of (XII) by means of triphenylphosphine and palladium tetrakis triphenylphosphine in acetic acid affords the corresponding silylated free acid (XIII), which is finally deprotected with tetrabutylammonium fluoride in THF - acetic acid, and treated with NaOH. (racemic). The allyl ester (XI) is obtained as follows: The hydrogenation of fluoroglucinol (XIV) with H2 over W4 Raney Nickel in ethanol gives, after crystallization, cis-1,3,5-trihydroxycyclohexane (XV), which is treated with tert-butyldiphenylsilyl chloride and imidazole in DMF to afford the bis-silylated compound (XVI). The oxidation of (XVI) with pyridinium chlorochromate in dichloromethane gives the protected cyclohexanone (XVII), which is oxidized again with m-chloroperbenzoic acid in dichloromethane yielding cis-4,6-bis(tert-butyldiphenylsilyloxy hexahydrooxepin-2-one (XVIII). The hydrolysis of (XVIII) with trifluoroacetic acid and refluxing allyl alcohol affords erythro-3,5-bis(tert-butyldiphenylsilyloxy)-6-hydroxyhexanoic acid allyl ester (XIX), which is finally oxidized with pyridinium chlorochromate in dichloromethane to give the desired oxo-ester (XI).
3) The esterification of L-malic acid (XX) with methanol and acetyl chloride gives the dimethyl ester (XXI), which is reduced with borane-dimethyl sulfide in THF yielding 3(S),4-dihydroxybutyric acid methyl ester (XXII). Partial protection of (XXII) with trityl chloride in pyridine affords 3(S)-hydroxy-4-(trityloxy) butyric acid methyl ester (XXIII), which is hydrolyzed with NaOH to the corresponding free acid (XXIV). The condensation of (XXIV) with succinic acid monoallyl ester, magnesium salt (XXV) by means of the carbonyl diimidazole (DCI) in THF gives 5(S)-hydroxy-3-oxo-6-(trityloxy)hexanoic acid allyl ester (XXVI), which is reduced with triethylborane and NaBH4 in THF and treated with H2O2 at -70 C to afford 3(R),5(S)-6-(trityloxy)hexanoic acid allyl ester (XXVII). The protection of the hydroxyl groups of (XXVII) with tert-butyldiphenylsilyl chloride and imidazole in DMF gives the fully protected ester (XXVIII), which is treated with trifluoroacetic acid in dichloromethane yielding erythro-3(R),5(S)-bis(tert-butyldiphenylsilyloxy)-6-hydroxyhexanoic acid allyl ester (XXIX). The oxidation of (XXIX) with pyridinium chlorochromate in dichloromethane affords the oxo-ester (XXX), which is condensed with phosphonate (X), as in method 2 above, to give ester (XXXI). The hydrolysis of (XXXI) with triphenylphosphine and palladium tetrakis triphenylphosphine as before yields the protected acid (XXXII), which is finally deprotected with tetrabutylammonium fluoride, also as before. [3(R),5(S)-erythro-isomer].
A synthesis of [14C]-labeled fluvastatin has been described: The acylation of fluorobenzene (I) with [14C]-bromoacetyl chloride (II) by means of AlCl3 gives the expected phenacyl bromide (III), which is condensed with N-isopropylaniline (IV) in hot ethanol yielding the tertiary amine (V). The cyclization of (V) by means of anhydrous ZnCl2 in refluxing ethanol affords the indole (VI), which is alkylated with 3-(N-methyl-N-phenylamino)acroleine (VII) by means of POCl3 in refluxing acetonitrile giving 3-[3-(4-fluorophenyl)-1-isopropylindol-2-yl]acroleine (VIII). The reductocondensation of (VIII) with tert-butyl acetoacetate (IX) by means of NaH and BuLi in THF yields 7-[3-(4-fluorophenyl)-1-isopropylindol-2-yl)-5-hydroxy-3-oxo-6-heptenoic acid tert-butyl ester (X), which is further reduced with NaBH4 and diethyl(methoxy)borane in THF to the dihydroxy compound (XI) as a mixture of the two syn-enantiomers (XI). Finally, this compound is hydrolyzed with NaOH in methanol to the expected sodium salt.
The Friedel-Crafts condensation of fluorobenzene (I) with chloroacetyl chloride (II) by means of AlCl3 gives the phenacyl chloride (III), which is cyclized with N-isopropylaniline (IV) by means of ZnCl2 to yield 3-(4-fluorophenyl)-1-isopropyl-1H-indole (V). The condensation of (V) with 3-(N-methyl-N-phenylamino)acrolein (VI) by means of POCl3 in acetonitrile affords 3-[3-(4-fluorophenyl)-1-isopropyl-1H-indol-2-yl]acrolein (VII), which is further condensed with tert-butyl acetoacetate (VIII) by means of BuLi and NaH in THF to provide 7-[3-(4-fluorophenyl)-1-isopropyl-1H-indol-2-yl]-5-hydroxy-3-oxo-6(E)-heptenoic acid tert-butyl ester (IX). The reduction of the ketonic group of (IX) with NaBH4 catalyzed by Et2B-OMe as chelating agent gives the diol (X) with a syn configuration. Finally, the tert-butyl ester group of (X) is hydrolyzed with NaOH in ethanol/water to afford the target fluvastatin sodium.