Synthesis of Optically Active 2-siloxycyclopropanecarboxylates by Asymmetric Catalysis, V. Baeyer–Villiger Oxidations of γ-Oxo Esters – Determination of the Absolute Configurations of Methyl 2-Siloxycyclopropanecarboxylates – Interpretation of the Enantioselective Cyclopropanations of Silyl Enol Ethers

✍ Scribed by Reißig, Hans-Ulrich ;Schumacher, Ralf ;Ferse, Dirk

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 563 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719971014

✦ Synopsis

Abstract

Racemic and enantiomerically enriched methyl 2‐siloxycyclopropanecarboxylates 1 have been ring‐opened to furnish γ‐oxo esters 2. Depending on the electronic properties of substituents, these could be transformed into either succinate derivatives 3 or 3‐oxybutanoates 4 by Baeyer‐Villiger oxidation. By comparison with known reference compounds the absolute configurations of 3a and 4d, and hence those of their cyclopropane precursors, could be determined. Further literature data on the optical rotations of related cyclopropanes have been collected and compared. A mechanistic interpretation of the asymmetric cyclopropanation of silyl enol ethers based on Pfaltz's model is suggested.