Highly Efficient Nucleophilic Addition of Alkyl Grignard Reagents to 17-Ketosteroids in the Presence of Cerium(III) Chloride: Synthesis of 17α-Propyl-17β-hydroxy-4-androsten-3-one, an Androgen Receptor Antagonist.

Abstract The addition of alkyl Grignard reagents to sterically hindered 17-ketosteroids was significantly enhanced by anhydrous cerium(III) chloride with notable suppression of abnormal reactions, while the addition products were obtained in good to excellent yields and high stereoselectivity.