Synthesis of Optically Active 2‐Siloxycyclopropanecarboxylates by Asymmetric Catalysis, IV. – Influence of Nucleophilicity of Silyl Enol Ethers on Stereoselectivities in Asymmetric Cyclopropanation Reactions
- 1 March 1997
- journal article
- Published by Wiley in European Journal of Organic Chemistry
- Vol. 1997 (3) , 521-526
- https://doi.org/10.1002/jlac.199719970312
Abstract
By variation of the aryl substituents of silyl enol ethers 1a–e and 1f–k, the influence of their nucleophilicity on the stereochemical outcome of cyclopropanation reactions was studied. Using the neutral Schiff‐base catalyst 2 · Cu(OAc)2, there was only a weak effect. On the other hand, with the cationic bisoxazoline complex 3· CuOTf a remarkable increase in the enantioselectivity was observed with more strongly electron‐attracting substituents such as a trifluoromethyl or nitro group.Keywords
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