ChemInform Abstract: Palladium-Catalyzed Intramolecular Allylic Alkylation Reaction in Marine Natural Product Synthesis. Enantioselective Synthesis of (+)-Methyl Pederate, a Key Intermediate in Syntheses of Mycalamides.
✍ Scribed by M. TOYOTA; M. HIROTA; Y. NISHIKAWA; K. FUKUMOTO; M. IHARA
- Publisher
- John Wiley and Sons
- Year
- 2010
- Weight
- 43 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0931-7597
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✦ Synopsis
Palladium-Catalyzed Intramolecular Allylic Alkylation Reaction in Marine Natural Product Synthesis. Enantioselective Synthesis of (+)-Methyl Pederate, a Key Intermediate in Syntheses of Mycalamides. -The carbonate precursor (VIII) for the title key step, leading to lactone (IX), is effectively prepared by diastereoselective aldol addition of the boron enolate, derived from oxazolidinone auxiliary (I), chemoselective reduction of thiol ester (IV) to the aldehyde (V), and stereoselective olefination yielding only the (E)-olefin (VII). The outcome of the selective δ-lactonization reaction of carbonate (VIII) depends dramatically on the palladium catalyst, the temperature, and the solvent. Best results are obtained with Pd(O-Ac) 2 /PPh 3 and DMF at 90 • C. Lactone (IX) is transformed by demethoxycarbonylation and further functional group conversions to pederate (XIII) and its epimer (XIV). -(TOYOTA, M.;