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Linked‐BINOL: An Approach towards Practical Asymmetric Multifunctional Catalysis
Author(s) -
Matsunaga Shigeki,
Ohshima Takashi,
Shibasaki Masakatsu
Publication year - 2002
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/1615-4169(200201)344:1<3::aid-adsc3>3.0.co;2-2
Subject(s) - chemistry , catalysis , ligand (biochemistry) , epoxide , lewis acids and bases , lanthanide , aldol reaction , lanthanum , enantioselective synthesis , enantiomeric excess , combinatorial chemistry , enantiomer , synergistic catalysis , medicinal chemistry , stereochemistry , organic chemistry , ion , biochemistry , receptor
The development and application of a novel linked‐1,1′‐binaphthol (linked‐BINOL) as an approach towards practical asymmetric multifunctional catalysis is described. Linked‐BINOL was first designed to increase the stability of a Ga‐Li‐BINOL complex against ligand exchange with 4‐methoxyphenol. An oxygen‐containing linked‐BINOL, which is a semi crown ether, was effective in both promoting the formation of a monomer complex and increasing the stability of the Ga‐Li complex. A Ga‐Li‐linked‐BINOL complex promoted the epoxide opening reaction in up to 96% enantiomeric excess (ee). Second, based on the X‐ray structural information of the Ga‐Li‐linked‐BINOL complex, we designed a more stable lanthanide linked‐BINOL complex. An air‐stable, storable, and reusable La‐linked‐BINOL complex promoted the Michael reaction in up to >99% ee. The catalyst activity remained unchanged after storage under air for 4 weeks. Calculations suggested that the linked‐BINOL would function as a pentadentate ligand in a lanthanum complex, thus efficiently improving the stability of the complex. Finally, the linked‐BINOL was applied to a new homobimetallic multifunctional catalysis. A dinuclear Zn‐Zn‐linked‐BINOL complex promoted the enantio‐ and diastereoselective direct aldol reaction in up to 99% ee, where one Zn cation might function as a Lewis acid and the other Zn‐phenoxide as a Brønsted base.