The β-Lactone Route to β-Hydroxy or α,β-Unsaturated γ- and δ-Lactones. Syntheses of (±)-Massoialactone and (±)-Prelactone B - Fournier, Lycia; Gaudel-Siri, Anouk; Kocieňski, Philip J; Pons, Jean-Marc (Synlett, 2003)