11-Ketotigogenin benzoate

This material in pyridine (120 ml) is benzoylated by addition of benzoyl chloride (12 ml). After 2 hr, water (20 ml) is added to destroy excess reagent, and the product is precipitated after a further 2 hr by addition of more water (200 ml). Addition of boiling methanol (135 ml) to a solution of the substance in boiling chloroform (45 ml) gives 11-ketotigogenin benzoate as lances (11.5g), mp 228-232° [aJo, —32°. A further 1.05 g is obtained from the mother liquors by evaporation and repeated crystallization. The total yield is 12.6 g, 83%. 

A sample of 11-ketotigogenin benzoate, prepared in a similar way from authentic 11-ketotigogenin, gives mp 231-233° [a]o, —32°. 

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