合成路线1

Friedel-Crafts acylation of 1-(phenylsulfonyl)pyrrole (XV) with chloroacetyl chloride (XVI) by means of AlCl3 in CH2Cl2 gives 2-chloro-1-[1-(phenylsulfonyl)pyrrol-3-yl]ethanone (XVII), which by condensation with sodium N-tosyl formamide (XVIII) (obtained by treatment of tosylamide (XIX) with NaOMe in MeOH to afford sodium tosylamide (XX), which is then formylated with HCOOEt in MeOH) using Bu4NBr in THF at 60 °C affords the corresponding keto amide (XXI). Decarbonylation of intermediate (XXI) by means of H2SO4 in MeOH at 60 °C followed by protection of the keto group with (CH2OH)2 using HC(OMe)3 produces acetal (XXII). Pictet-Spengler cyclization of protected amine (XXII) with (HCHO)n in the presence of TFA in CH2Cl2 affords the 1,5,6,7-tetrahydro-4H-pyrrolo[2,3-c]pyridin-4-one derivative (XXIII) , which by O-methylation with HC(OMe)3 using MsOH and CMNOOH in MeOH yields the enol ether (XXIV). Redox elimination of the tosyl group in compound (XXIV) by means of Na2S2O3 and Et3N gives the pyrrolo[2,3-c]pyridine derivative (XXV) , which can also be prepared by treatment of N-protected amine (XXIII) with HC(OMe)3 in the presence of MsOH or Tf2O and CMNOOH or AIBN . Oxidation of intermediate (XXV) with H2O2 using MeReO3 or phthalic anhydride in CH2Cl2 results in the pyridine-N-oxide (XXVI). Bromination of compound (XXVI) with PyBroP and K3PO4 in trifluorotoluene, followed by treatment with NaOH in i-PrOH at 80 °C yields the bromopyridine (XXVII), which by Friedel-Crafts C-3-acylation with methyl oxalyl chloride (VI) using AlCl3 in CH2Cl2/MeNO2 at 0 °C produces the keto ester (XXVIII). Hydrolysis of the methyl ester (XXVIII) with aqueous NaOH and subsequent treatment with HBr affords (7-bromo-4-methoxypyrrolo[2,3-c]pyridin-3-yl)(oxo)acetic acid hydrobromide salt (XXIX) .