Complex sentence: The conversion consists of the demethylation of the C19 position and the aromatization of the A ring, which is the same reaction that occurs in the conversion of testosterone to estradiol via aromatase.
Split into simpler sentences: The conversion consists of the demethylation of the C19 position and the aromatization of the A ring. This reaction is similar to the conversion of testosterone to estradiol via aromatase.