An efficient synthesis of the 25-hydroxy Windaus–Grundmann ketone

A short and efficient synthesis of the 25-hydroxy Windaus–Grundmann ketone from the Inhoffen–Lythgoe diol is described (seven steps, 70% overall). The most relevant feature of the synthesis is the preparation of the Wittig reagent 3 from cheap and commercially available starting materials. Pure 3 can be obtained in multigram quantities for achieving clean and efficient Wittig reactions.