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taken into 15 mL chloroform or ether, washed twice
with 15 mL saturated brine solution and finally washed
with water. The organic layer was dried over anhydrous
magnesium sulfate and the solvent was removed using a
rotary evaporator. For further purification/separation
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tive TLC or by column chromatography. When formic
acid was used, the filtrate and washings were neutral-
ized with ammonia then evaporated under vacuum and
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