反应详情

Concentrated ammonium hydroxide (3 mL) was added to a suspension of the product of Example 29 (1.95 g.) in 12 mL of deoxygenated water. The reaction mixture, which became homogeneous in less than one minute, was stirred for 15 minutes. At this time, the pH was adjusted to about 1.5 with potassium bisulfate and the resulting aqueous mixture was extracted with ethyl acetate (2×150 mL). The combined organic layers were washed with brine, dried (MgSO4), and concentrated to afford an oily residue. This residue was flash chromatographed on a 5×12 cm silica gel column using hexane:ethyl acetate:acetic acid, 65:35:1. The pure fractions were concentrated and the residue was coevaporated from heptane several times to afford a white solid. Trituration with hexane and drying 18 hours under high vacuum afforded 1.175 g. of the title isomer A compound as a white solid, m.p. 96°-98° C., TLC Rf =0.38 (ethyl acetate:hexane:acetic acid, 40:60:2). [α]D =-43.2 (c=0.60, methanol).

1. waitThe reaction mixture, which became homogeneous in less than one minute
2. extractionthe resulting aqueous mixture was extracted with ethyl acetate (2×150 mL)
3. washThe combined organic layers were washed with brine
4. dry with materialdried (MgSO4)
5. concentrationconcentrated
6. customto afford an oily residue
7. customchromatographed on a 5×12 cm silica gel column
8. concentrationThe pure fractions were concentrated
9. customto afford a white solid
10. dry with materialTrituration with hexane and drying 18 hours under high vacuum
11. customafforded 1.175 g