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Trifluoroacetic acid (1.5 ml) was added to a solution of 7 (5.8 g, 15.26 mmol) in 20% aqueous methanol. The solution was stirred for 40 min at room temperature and then diluted with 400 ml of ethyl acetate and washed with 400 ml of 5% sodium bicarbonate solution followed by 400 ml of water. The organic solution was dried over sodium sulfate and evaporated. The residue was purified by silica gel chromatography eluting with a gradient of 50% hexane in ethyl acetate to 100% ethyl acetate to 5% methanol in ethyl acetate. The pure product fractions were evaporated affording an oil: 1.1 g (20%) yield; TLC (5% methanol in ethyl acetate), Rf=0.64; 1H NMR (CDCl3) 7.62 (1H, s, acetal CH), 7.44 (2H, d, J=8.7 Hz, aromatic), 6.90 (2H, d, J=8.6 Hz, aromatic), 3.98 (2H, t, J=6.3 Hz, CH2), 3.68 (1H, m, CH), 3.46 (2H, m, CH2), 2.11 (6H, s, Acetyl), 1.82 (2H, m, CH2), 1.55 (4H, m, CH2). Anal. Calcd for C17H24O7: C, 59.99; H, 7.11. Found: C, 60.26; H, 7.08.

1. washwashed with 400 ml of 5% sodium bicarbonate solution
2. dry with materialThe organic solution was dried over sodium sulfate
3. customevaporated
4. customThe residue was purified by silica gel chromatography
5. washeluting with a gradient of 50% hexane in ethyl acetate to 100% ethyl acetate to 5% methanol in ethyl acetate
6. customThe pure product fractions were evaporated
7. customaffording an oil
8. custom1.1 g (20%) yield