The first synthesis of Krempene B

[Display omitted] ► The first synthesis of marine pregnene Krempenes B (1). ► The dienone–phenol rearrangement of steroids A ring. ► Compound 7 and Krempenes B (1) was confirmed by X-ray crystal structure analysis. ► Provide raw materials for the biological activity of 1 and analogues of 1. The synthesis of Krempene B, which can be isolated from the marine soft coral Cladiella krempfi, is achieved in 23.9% overall yield from commercially available 3β-acetoxy-5-pregnen-20-one by 11 steps. Key transformations include the dienone–phenol rearrangement of steroids and Wittig reaction.