[Cr](Cl)([O-])(=O)=O.[NH+]1C=CC=CC=1.C([O-])(=O)C.[Na+].[OH:17][CH2:18][CH2:19][CH2:20][CH2:21][C:22]1[CH:31]=[CH:30][C:25]([C:26]([O:28][CH3:29])=[O:27])=[CH:24][CH:23]=1>C(Cl)Cl.C(OCC)C>[C:26]([C:25]1[CH:30]=[CH:31][C:22]([CH2:21][CH2:20][CH2:19][CH:18]=[O:17])=[CH:23][CH:24]=1)([O:28][CH3:29])=[O:27]To mixture of 4.19 g (1.5 eq) of pyridinium chlorochromate and 1.76 g (1.0 eq) of sodium acetate in 100 mL of dry methylene chloride are added, under nitrogen and with stirring, 2.70 g 1.0 eq) of methyl 4-(4-hydroxybutyl)benzoate in 50 mL of dry methylene chloride. The reaction mixture is stirred 12 hours, diluted with diethyl ether, and filtered. After concentration at reduced pressure, the residue is distilled under vacuum to yield 4-(4-carbomethoxyphenyl)-butanal as an oil, b.p. 131° C. at <1 torr; IR (film) νmax 2950, 2720, 1722, 1612, 1285, and 1110 cm-1 ; 1H NMR (CDCl3) delta 9.77 (m, 1H, --CHO), 7.98 (d, J=9 Hz, 2H, Ar), 7.24 (d, J=8.2 Hz, 2H, Ar), 3.90 (s, 3H, --CH3), 2.72 (t, 2H, benzyl), 2.47 (mm, 2H, --CH2CHO), 1.95 (m, 2H, --CH2).
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