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Optically Active Helical Poly[( S )‐3‐vinyl‐2,2′‐dihydroxy‐1,1′‐binaphthyl]: New Ligand for Asymmetric Addition of Diethylzinc to Aryl Aldehyde
Author(s) -
Chen Yehui,
Qin Guochang,
Yang Liwen,
Yang Nianfa
Publication year - 2015
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201400819
Subject(s) - diethylzinc , chemistry , aldehyde , catalysis , aryl , yield (engineering) , enantiomer , polymer chemistry , ligand (biochemistry) , enantiomeric excess , alcohol , vinyl alcohol , enantioselective synthesis , medicinal chemistry , polymer , organic chemistry , alkyl , biochemistry , materials science , receptor , metallurgy
Poly[( S )‐3‐vinyl‐2,2′‐dihydroxy‐1,1′‐binaphthyl] (L*) was obtained by taking off the protecting groups of poly[( S )‐3‐vinyl‐2,2′‐bis(methoxymethoxy)‐1,1′‐binaphthyl] (poly‐ 1 ). L* was proved to keep a stable helical conformation in solution. The application of helical L* in the asymmetric addition of diethylzinc to aldehydes has been studied. The catalytic system employing 10 mol% of L* and 150 mol% of Ti(O i Pr) 4 was found to promote the addition of diethylzinc to a wide range of aromatic aldehydes, giving up to 99% enantiomeric excess ( ee ) and up to 93% yield of the corresponding secondary alcohol at 0°C. The chiral polymer can be easily recovered and reused without loss of catalytic activity as well as enantioselectivity.