The Preparation of α‐Alkylidene‐γ‐Butyrolactones Using a Telescoped Intramolecular Michael/Olefination (TIMO) Sequence: Synthesis of (+)‐Paeonilactone B

Abstract

Abstract A novel telescoped intramolecular Michael addition/proton transfer/HWE olefination sequence has been developed to provide rapid access to α‐alkylidene‐γ‐butyrolactones. This methodology has been applied to prepare a range of tetrahydrobenzofuran‐2,5‐diones, and related systems, and also utilised in an extremely short synthesis of the natural product (+)‐paeonilactone B in enantiomerically pure form. In addition, preliminary experiments are described that illustrate a palladium‐catalysed variant proceeding by way of a π‐allyl intermediate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)