A Repetitive Approach to the Synthesis of Medium and Large Ring Compounds with a Ring-Opening/Ring-Closure Cascade Reaction of Siloxycyclopropane Derivatives as Crucial Step
✍ Scribed by Astrid Ullmann; Hans-Ulrich Reißig; Otto Rademacher
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 379 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
Starting from siloxycyclopropyl-substituted dimethyl derivatives 11, 12, 13, cycloeicosanone derivative 16, cyclotetradecanone derivative 19 and cyclononane malonates 1 and 2 a chain elongation was performed to give new malonates 8, 9, 10, and 18 in reasonable overall yield. derivative 22 (together with 23). The efficiency of this reaction including an intramolecular Michael addition is Further elongation by five carbon atoms transforms 10 into 15. Precursor 21 was prepared by alkylation of discussed. The sequence allows efficient synthesis of medium and large carbocycles by a highly flexible building cyclopropanecarboxylate 20 with dibromide 17 and subsequent treatment with sodium dimethyl malonate.
block system involving in principle unlimited repetition of construction steps. An X-ray analysis of 19 reveals its crown-Compounds 8, 9, 10, 15, 18, and 21 were subjected to cesium fluoride under high dilution which induced a ring-opening/ like conformation which is slightly distorted to a more planar skeleton compared with a ten-membered ring analog 24. ring-closure cascade reaction giving cyclopentadecanone [ ] X-ray analysis. and decarboxylation may be competing processes which