反应条件
1: 6α, 9α-difluoro-11β-hydroxy-16α-methyl-3-oxo-17α-hydroxy-androsta-1,4-diene-17β-carboxylic acid With 1,1'-carbonyldiimidazole in tetrahydrofuran T=5°C; 18 h; Inert atmosphere; 2: methyl thioacetic acid in tetrahydrofuran T=5 - 25°C; 7 h; Inert atmosphere; Product distribution / selectivity;