21-hydroxyprogesterone <=> 20-hydroxy-3-oxopregn-4-en-21-al
21-hydroxyprogesterone <=> 20-hydroxy-3-oxopregn-4-en-21-al
21-hydroxyprogesterone <=> 20-hydroxy-3-oxopregn-4-en-21-al
21-hydroxyprogesterone <=> 20-hydroxy-3-oxopregn-4-en-21-al