合成路线1

A new synthesis of the active (R,R)-isomer of SM-8668 has been reported: The Friedel-Crafts condensation of 1,3-difluorobenzene (I) with 2-bromopropionyl bromide (II) by means of AlCl3 gives the corresponding propiophenone (III), which is treated with sodium methylmercaptide to yield 2',4'-difluoro-2-(methylsulfanyl)propiophenone (IV). The reaction of (IV) with trimethylsulfoxonium chloride affords the epoxide (V) as a D,L-threo-mixture of isomers, which is treated with a chiral carboxylic acid (VI), giving the diastereomeric mixture of esters (VII). The separation of the isomers by column chromatography or fractional crystallization affords the (2R,3R)-isomer (VIII), which by hydrolysis with NaOH is converted to the diol (IX). The epoxidation of the diol (IX) with mesyl chloride, NaOH and benzyltriethylammonium chloride yields the (2R,3R)-epoxide (X), which is condensed with 1,2,4-triazole (XI) by means of NaOH to give the precursor (XII). Finally, this compound is oxidized with H2O2 and sodium tungstate.