[C:1]([NH:5][S:6]([CH3:9])(=[O:8])=[O:7])([CH3:4])([CH3:3])[CH3:2].C([Li])CCC.[F:15][C:16]1[CH:25]=[CH:24][C:19]([C:20](OC)=[O:21])=[CH:18][CH:17]=1.C(O)(=O)C>C1COCC1.C(OCC)(=O)C>[C:1]([NH:5][S:6]([CH2:9][C:20]([C:19]1[CH:24]=[CH:25][C:16]([F:15])=[CH:17][CH:18]=1)=[O:21])(=[O:8])=[O:7])([CH3:4])([CH3:3])[CH3:2]N-tert-Butylmethanesulfonamide (1.00 g) was initially charged in THF (10 ml) and cooled to −78° C. n-Butyllithium (1.6 N in hexane, 9.00 ml) was added dropwise. Subsequently, the mixture was warmed up to 0° C. within 5 minutes, stirred for 5 further minutes and cooled again to −78° C. Methyl 4-fluorobenzoate (1.56 g) in THF (10 ml) dissolved and to −78° C. cooled. The solution prepared above was added dropwise at low temperature. After the addition had ended, the mixture was allowed to come to room temperature and stirred for a further 1 hour. After the addition of acetic acid (0.82 ml) and ethyl acetate (50 ml), the mixture was washed with saturated sodium hydrogencarbonate solution (50 ml) and saturated sodium chloride solution (50 ml). The organic phase was dried over magnesium sulfate, filtered and concentrated by rotary evaporation. Purification was effected via normal phase with an n-heptane/ethyl acetate gradient. The fractions of value were combined, concentrated by rotary evaporation and dried under reduced pressure. This gave the product (661 mg) with a molecular weight of 273.3 g/mol (C12H16FNO3S), MS (EST): m/e=296 (M+Na+).
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