反应详情

To a flask containing a solution of 3α-hydroxy-5β-pregnan-20-one (5.15 g, 16.5 mmol)in methanol (100 mL) was added a solution of bromine (1.1 mL) in methanol (30 mL) dropwise in such a rate to maintain the brown color of the bromine until this color was persistent. Then water (200 mL) was added and the mixture was extracted with CH2Cl2 (3×100 mL). The combined extracts were dried over Na2SO4. Removal of the solvent resulted in the product as a foamy white solid (6.63 g). Other 21-bromo-pregnan-20-ones (3β-ethynyl-3α-hydroxy-21-bromo-5β-pregnan-20-one, 3β-methyl-3α-hydroxy-21-bromo-5α-pregnan-20-one and 3α-hydroxy-3β-trifluoromethyl-12-bromo-5β-19-norpregnan-20-one) were synthesized using the same method.

1. extractionthe mixture was extracted with CH2Cl2 (3×100 mL)
2. dry with materialThe combined extracts were dried over Na2SO4
3. customRemoval of the solvent