Trimethyl orthoformate → 2-Bromo-1-[3-(pentafluorosulfanyl)-5-pyrrolidin-1-ylphenyl]ethanone

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Reaction Steps

1-[3-(Pentafluorosulfanyl)-5-pyrrolidin-1-ylphenyl]ethanone (78 mg) was dissolved in methanol (5 ml) and admixed while stirring with trimethyl orthoformate (80 mg) and DL-10-camphorsulfonic acid (57 mg). After stirring at RT for 3 h, THF (5 ml) was added, followed by phenyltrimethylammonium tribromide (83 mg). After stirring at RT for 3 h, the mixture was left to stand overnight. Then the mixture was heated to 50° C. for 3 h and subsequently dried. The residue was taken up in ACN, admixed with 2N sulfuric acid and stirred for 30 min. Then it was admixed with water and concentrated. The residue was purified by means of preparative HPLC. The product-containing fractions were combined, freed of the acetonitrile, admixed with saturated sodium hydrogencarbonate solution and extracted three times with ethyl acetate. The combined extracts were dried over magnesium sulfate, filtered and concentrated. 9 mg of the desired compound were obtained.

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