Example 101
Compound 104. To a stirred suspension of ketone 101 (94 mg, 0.333 mmol) in dry chloroform (10 mL), oxalyl chloride (30 μL, 0.33 mmol) was added upon cooling to 0-5° C. The resulted red solution was stirred for 1 h, then N,N-diethyl-m-anisidine (60 mg, 0.33 mmol) was added. The reaction was allowed to warm to rt, stirred for 16 h and diluted with CHCl3 (60 mL). Chloroform solution was shaken with sat. NaHCO3 (40 mL) until water layer turned almost colorless. The organic layer was washed with sat. NaHCO3 (20 mL) and extracted with 10% HCl (2×30 mL). The combined acid extract was washed with CHCl3 (2×15 mL; discarded), the aqueous solution was saturated with sodium acetate and extracted with CHCl3 (4×30 mL). The extract was washed with brine (30 mL), and evaporated. The crude product was purified by chromatography on silica gel column (2×40 cm bed, packed with 10% MeOH and 1% AcOH in CHCl3) eluant: 10% MeOH and 1% AcOH in CHCl3 to give the product 104 (3 mg, 2%) as a purple wax.
