Enantioselective addition of diethylzinc to aldehydes catalyzed by titanium(IV) complexes of n-sulfonylated β-amino alcohols with four stereogenic centers

✍ Scribed by Sheng-Hsiang Hsieh; Han-Mou Gau

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 148 KB
• Volume: 18
• Category: Article
• ISSN: 0899-0042
• DOI: 10.1002/chir.20279

✦ Synopsis

Abstract

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.