| 摘要 |
1,233,692. Dehydrohalogenation of 3-oxo-2,4- dihalosteroids. SCHERICO Ltd. 13 Jan., 1969 [16 Jan., 1968], No. 1811/69. Heading C2U. A 3-oxo-#<SP>1</SP>,<SP>4</SP>-steroid is prepared by dehydrohalogenation of a 3-oxo-2,4-dihalo steroid (I) by heating it with an alkali or alkaline earth metal oxide or carbonate (II), a tertiary amide (III), and water (IV) in an amount of 1-10% of the volume of III. A lithium halide (V) may also be present. Specified reactants are: I-many specific 2,4-dibromo-steroids of the androstane, pregnane and cholestane series; II-MgO, LiCO 3 , CaCO 3 , MgCO 3 ; III-dimethylformamide, dimethylacetamide, N - methyl - 2- pyrrolidone; V-LiBr. Preferred reactant ratio ranges are: II/I (mole/mole) = 1-15; III/I (ml/gm.) = 5-15; IV/III (v/v) = 0À01- 0À04; V/I (mole/mole) = 0À1-5À0. A 9α-chloro- 11#-hydroxy grouping may be simultaneously converted to a 9,11-epoxy group (Example 5). Any ester group hydrolysed during the reaction may subsequently be regenerated. |
