ChemInform Abstract: Synthesis of Cyclic Bis(trimethylsilyl) Enol Ethers and Their [3 + 4] and [3 + 5] Annulation Reactions with Dicarbonyl Electrophiles. Access to Highly Functionalized Tricyclic Ethers Possessing trans Intrabridgehead Stereochemistry.
✍ Scribed by Gary A. Molander; Bernard Bessieres; Paul R. Eastwood; Bruce C. Noll
- Publisher
- John Wiley and Sons
- Year
- 2010
- Weight
- 40 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0931-7597
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✦ Synopsis
Synthesis of Cyclic Bis(trimethylsilyl) Enol Ethers and Their [3 + 4] and [3 + 5] Annulation Reactions with Dicarbonyl Electrophiles. Access to Highly Functionalized Tricyclic Ethers Possessing trans Intrabridgehead Stereochemistry. -The title investigation is presented in connection with studies on the total synthesis of ingenol (XVIII), a naturally occurring diterpene which plays an important role in cellular signal transduction and carcinogenesis. Cyclic bis(trimethylsilyl) enol ethers are prepared for the first time starting from cycloalkanone carboxylates using different conditions depending on the ring size. In all cases 90-95% conversion to the desired product is achieved together with 5-10% of the corresponding monosilyl enol ethers (not shown). Application of the bis(silyl) enol ethers as dinucleophiles in annulation reactions with various dicarbonyl compounds furnishes tricyclic keto ethers in moderate to good yields. Trans intrabridgehead stereochemistry is obtained when 9-to 12-membered rings are utilized.
-(MOLANDER, GARY A.;