An Unexpected Transannular [4+2] Cycloaddition during the Total Synthesis of (+)‐Norcembrene 5
| Autor: | Michael Breunig, Po Yuan, Tanja Gaich |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
transannular cycloaddition
010405 organic chemistry Chemistry Stereochemistry Communication furanocembranoid norcembrenolide ring-closing metathesis total synthesis transannular [4+2] cycloaddition Total synthesis General Chemistry ring-closing metathesis 010402 general chemistry Metathesis 01 natural sciences Communications Catalysis Cycloaddition 0104 chemical sciences Ring-closing metathesis terpenoids Diels–Alder reaction ddc:540 total synthesis Structural motif Natural Products Synthesis Norcembrenolide |
| Zdroj: | Angewandte Chemie (International Ed. in English) |
| ISSN: | 1521-3773 1433-7851 |
| DOI: | 10.1002/anie.201912613 |
| Popis: | We report a concise and versatile total synthesis of the diterpenoid (+)‐norcembrene 5 from simple building blocks. Ring‐closing metathesis and an auxiliary‐directed 1,4‐addition are the key steps of our synthetic route. During the synthesis, an unprecedented, highly oxidized pentacyclic structural motif was established from a furanocembranoid through transannular [4+2] cycloaddition. They may look alike… During studies toward the total synthesis of the norditerpene natural product norcembrene 5, one diastereomer of a key intermediate (α‐OAc at C13) underwent clean and spontaneous Diels–Alder cycloaddition at room temperature (see scheme). However, the corresponding β isomer did not undergo a Diels–Alder reaction, but was oxidized to the corresponding furanone, which was further transformed into norcembrene 5. |
| Databáze: | OpenAIRE |
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