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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
Author(s) -
Reißig HansUlrich,
Schumacher Ralf,
Ferse Dirk
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719971014
Subject(s) - chemistry , cyclopropanation , cyclopropane , enantioselective synthesis , enol , silylation , stereochemistry , absolute configuration , interpretation (philosophy) , catalysis , ring (chemistry) , organic chemistry , computer science , programming language
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.