[C:1]([C:4]1[CH:11]=[CH:10][C:7]([CH:8]=[O:9])=[CH:6][CH:5]=1)([OH:3])=[O:2].[CH3:12][Si](C=[N+]=[N-])(C)C.C([O-])(O)=O.[Na+]>C(Cl)Cl>[CH3:12][O:2][C:1](=[O:3])[C:4]1[CH:11]=[CH:10][C:7]([CH:8]=[O:9])=[CH:6][CH:5]=1To a suspension of 9.6 g (63.6 mmol) of 4-carboxybenzaldehyde (Aldrich Chemical Co.) in 100 mL of CH2Cl2 at 0° C. was added excess trimethylsilyldiazomethane and the resulting mixture was allowed to stir at 0° C. for 1 h. The mixture was poured into saturated aqueous NaHCO3 and extracted three times with ethyl acetate. The combined organic extracts were dried over MgSO4, filtered and concentrated to give 4.3 g of the ester 167 as an oil. 1H NMR consistent with the product.
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