[CH3:1][O:2][C:3](=[O:11])[C:4]1[CH:9]=[CH:8][C:7]([OH:10])=[CH:6][CH:5]=1.N1C=CC=CC=1.[CH3:18][S:19](Cl)(=[O:21])=[O:20]>C1COCC1>[CH3:1][O:2][C:3](=[O:11])[C:4]1[CH:9]=[CH:8][C:7]([O:10][S:19]([CH3:18])(=[O:21])=[O:20])=[CH:6][CH:5]=14-Hydroxy-benzoic acid methyl ester (3.19 g, 21 mmol) was dissolved together with pyridine (1.97 g, 25 mmol) in dry THF (20 mL) and after cooling down to 0° C., methanesulfonyl chloride (2.29 g, 20 mmol) was added dropwise. The ice bath was removed and mixture was stirred at r.t. for 5 h. After diluting with DCM and extraction with water and aq. HCl (2N), the organic layer was dried (MgSO4) and evaporated to afford the crude but highly pure product as a solid which was used in the next step without further purification (4.38 g, 95.1%). 1H NMR (400 MHz, CDCl3): δ 8.07-8.09 (d, 2H), 7.32-7.34 (d, 2H), 3.90 (s, 3H), 3.16 (s, 3H).
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