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Asymmetric catalysis with self‐organized chiral lanthanum complexes: Practical and highly enantioselective epoxidation of α,β‐unsaturated ketones
Author(s) -
Daikai Kazuhiro,
Hayano Tetsuji,
Kino Rie,
Furuno Hiroshi,
Kagawa Takumi,
Inanaga Junji
Publication year - 2002
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10167
Subject(s) - chemistry , enantioselective synthesis , cumene hydroperoxide , lanthanum , enantiomeric excess , catalysis , enantiomer , epoxy , alkyl , chalcone , organic chemistry , peroxide , medicinal chemistry
A highly efficient and practical method for obtaining α,β‐epoxy ketones with high optical purities was developed. The chiral lanthanum complex self‐organized in situ from lanthanum triisopropoxide, ( R )‐BINOL, triarylphosphine oxide, and alkyl hydroperoxide (1:1:1:1) was found to catalyze the epoxidation of α,β‐unsaturated ketones with tert ‐butyl hydroperoxide or cumene hydroperoxide at room temperature to give the corresponding epoxy ketones in high enantioselectivities (up to >99% enantiomeric excess (ee)). A remarkably high asymmetric amplification, a positive nonlinear effect, was observed in the epoxidation of chalcone, which strongly suggests the formation of a dinuclear peroxide‐involved μ‐complex as the active catalyst. Chirality 15:83–88, 2003. © 2002 Wiley‐Liss, Inc.