Synthesis of pinguisane-type sesquiterpenoids acutifolone a, pinguisenol, and bisacutifolones by a diels-alder dimerization reaction

The total synthesis of pinguisane-type sesquiterpenoids, acutifolone A (1) and pinguisenol (2), has been achieved by using the Mukaiyama aldol reaction as the key step. The intermolecular Diels-Alder reaction of these monomeric natural products successfully led to stereoselective dimerization, leading to bisacutifolones A (3) and B (4). Theoretical calculations revealed that the dimerization reaction proceeded through the most stable transition state. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).