Hydrochloric Acid → 3beta-tert-Butyldimethylsilyloxy-4,4-dimethyl-5alpha-chola-8,14-dien-24 oic acid-N-methoxy-N-methyl amide

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Reaction Conditions

Reaction Steps

3β-tert-Butyldimethylsilyloxy-4,4-dimethyl-5α-chola-8,14-dien-24-oic acid (5.0 g) is dissolved in 250 ml of dry dichloromethane. After cooling to −15° C., 2.14 ml of N-methylmorpholine and 1.27 ml isobutylchloroformate is added and the mixture is stirred at −15° C. for 20 minutes, whereupon 0.98 g of N,O-dimethylhydroxy/amine, HCl is added and the mixture is stirred overnight and the temperature is slowly elevated to room temperature. After aqueous work-up, 3β-tert-butyldimethylsilyloxy-4,4-dimethyl-5α-chola-8,14-dien-24-oic acid-N-methoxy-N-methyl amide (5.37 g) is obtained. Melting point: 134-135° C. 1H-NMR (CDCl3, 300 MHz): δ=5.35 (1H, s); 3.69 (3H, s); 3.2 (1H, m); 3.18 (3H, s); 0.9 (9H, s); 0.04 (6H, m).

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