N1[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.COC1C=[C:13]([S:15]C)C=CC=1CO.CCCCCC.C[CH2:26][O:27]C(C)=O.C(Cl)Cl.C[C:35](C)=[O:36].[CH3:38]CCCCC.C(OCC)(=O)C>C(Cl)Cl.CCCCCC.[O-2].[O-2].[O-2].[Cr+6]>[CH3:35][O:36][C:2]1[CH:38]=[C:6]([S:15][CH3:13])[CH:5]=[CH:4][C:3]=1[CH:26]=[O:27]Pyridine (4.8 mL, 60 mmol, 12 eq) was added under nitrogen to a mixture of chromium trioxide (fresh, 2 g, 20 mmol) in dry methylene chloride (15 mL) cooled over an ice bath. The mixture was stirred at 0° C. for 1 hour and Celite powder (1 g) and a solution of (2-methoxy-4-methylsulfanyl-phenyl)-methanol (934 mg, 5.07 mmol) in methylene chloride (10 mL) was added. The progress of the reaction was followed by TLC (silica gel, hexane-EtOAc-CH2Cl2-acetone (3:3:3:1 v/v) and hexane-ethyl acetate (7:3 v/v)) and analytical HPLC and when complete, the mixture was applied to a silica gel column (made up in hexane) and the column eluted with methylene chloride. Pure fractions were combined and concentrated to provide 2-methoxy-4-methylsulfanyl-benzaldehyde (730 mg, 79%). LCMS: MH+ 183.2.
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