Divergent synthesis of pseudoenantiomers for ABC-ring moiety of steroids

Steroid family has various bioactivities and characteristic polycyclic structure. Although several synthetic methods have been reported, more efficient way is desired for medicinal chemistry. In this Letter, we synthesized pseudoenantiomers of tricyclic enones toward both enantiomers for ABC-ring moiety of steroids utilizing d-mannitol as a chiral source. The key steps are radical domino cyclization of polyalkenyl-β-keto ester into tricyclic keto ester and subsequent dealkoxycarbonylation.