Primary metabolite from human hepatic microsome metabolism. Likely formed by CYP3A4, as this enzyme is responsible for 6β-hydroxylation pathways in other steroids.
References
Verhoeven, C. H. J.; Krebbers, S. F. M.; Wagenaars, G. N.; Vos, R. M. E. In Vitro and in Vivo Metabolism of Desogestrel in Several Species. DRUG Metab. Dispos. 1998, 26 (9), 927–936.