[CH2:1]([O:8][C:9]1[CH:16]=[CH:15][C:12]([CH:13]=[O:14])=[CH:11][C:10]=1[OH:17])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C(=O)([O-])[O-].[K+].[K+].[CH:24]1(Br)[CH2:28][CH2:27][CH2:26][CH2:25]1.O>CN(C)C=O.C(OCC)C>[CH2:1]([O:8][C:9]1[CH:16]=[CH:15][C:12]([CH:13]=[O:14])=[CH:11][C:10]=1[O:17][CH:24]1[CH2:28][CH2:27][CH2:26][CH2:25]1)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1A stirred solution of 4-benzyloxy-3-hydroxybenzaldehyde (60.9 g; that is prepared as described in Reference Example 36) in dry dimethylformamide (270 mL) under nitrogen is treated portionwise with potassium carbonate (79.5 g). After stirring at room temperature for 45 minutes, it is treated with cyclopentyl bromide (34.3 mL), and the resulting suspension is heated at 60° C. for 8 hours. After cooling, the solution is evaporated to low bulk under reduced pressure, to give an oil. This oil is treated with water (250 mL) and diethyl ether (300 mL), and the aqueous layer is washed with further quantities of diethyl ether (2×50 mL). The combined ethereal extracts are washed with brine (1×50 mL) and with water (3×50 mL), dried over magnesium sulfate and evaporated. The resulting residue is crystallized from methanol, to give 4-benzyloxy-3-cyclopentyloxybenzaldehyde (79 g), m.p. 55°-56° C. [Elemental analysis: C,77.1; H,6.9%; calculated: C,77.0; H,6.8%].
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