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Enantioselective addition of diethylzinc to aldehydes catalyzed by titanium(IV) complexes of n ‐sulfonylated β‐amino alcohols with four stereogenic centers
Author(s) -
Hsieh ShengHsiang,
Gau HanMou
Publication year - 2006
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.20279
Subject(s) - diethylzinc , stereocenter , chemistry , denticity , catalysis , enantioselective synthesis , alcohol , amino acid , titanium , ligand (biochemistry) , stereochemistry , organic chemistry , metal , biochemistry , receptor
An N ‐sulfonylated β‐amino alcohol ( R , S , S , R )‐ 9 with four stereogenic centers is prepared. The titanium complex of 9 is an effective catalyst to induce excellent enantioselectivities for diethylzinc addition to aromatic aldehydes with ee values up to 99%. The feature of doubling the quantity of Ti(O‐i‐Pr) 4 required relative to the catalytic system of the Ti complex of bidentate N ‐sulfonylated β‐amino alcohols suggests that the two N ‐sulfonylated β‐amino alcohol moieties in 9 behave as two independent bidentate ligands in the catalytic system. The results obtained using ligand 15 having one N ‐sulfonylated β‐amino alcohol blocked support the argument of two independent active bidentate moieties in 9 . Chirality, 2006. © 2006 Wiley‐Liss, Inc.