β-Cleavage of Bis(homoallylic) Potassium Alkoxides. Preparation of 3-Hydroxypropyl and 4-Hydroxybutyl Propenyl Ketones from γ- and δ-Lactones. Synthesis of (±)-Rose oxide

Starting from γ‐ and δ‐lactones 1–3, a two‐step preparation of 3‐hydroxypropyl and 4‐ hydroxybutyl propenyl ketones 10–18 is described, involving as the key step the β‐cleavage of the bis(homoallylic) potassium alkoxides 4a–9a. The novel methodology is illustrated by a short synthesis of (±)‐rose oxide(20).