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The Telescoped Intramolecular Michael/Olefination (TIMO) Approach to a-Alkylidene-g-butyrolactones: Synthesis of (+)-Paeonilactone B Significance: (+)-Paeonilactone is isolated from the root of Paeonia albiflora Pallas, which has been used for pain relief in Chinese and Japanese folk medicine. The cornerstone of this synthesis is the construction of the a-methylene-g-butyrolactone by a Telescoped Intramolecular Michael/Olefination (TIMO) tandem reaction. Comment: The TIMO tandem reaction entails an intramolecular Michael addition, proton transfer to give the phosphonate anion, and then a HWE olefination. The scope of the TIMO reaction was explored in eight examples showing that it tolerates five-and seven-membered-ring 4-hydroxycycloalkenones and aldehyde components. O OH O OTBS O OTBS O OH OH O O OH (EtO) 2 P O O OH O O LDA, THF then MeI -78 to -20 °C 55% (dr = 1:1)1. LDA, THF, then TESCl, -78 °C to r.t. 2. DMDO, CH 2 Cl 2 , Me 2 CO, -50 °C 3. AcOH, aq THF, 50 °C 52%

Aus den Hydrochinonen (I) entstehen mit einem Äquivalent des Oxidationsmittels Thallium= (III)‐nitrat die Chinone (II), während mit zwei Äquivalenten des Oxidationsmittels aus den Phenolen (III) die Chinone (IV) gebildet werden.