Asymmetric hydroesterification of styrene using catalysts with planar-chiral ferrocene oxazoline ligands

✍ Scribed by Lailai Wang; Wai Him Kwok; Albert S.C. Chan; Tao Tu; Xuelong Hou; Lixin Dai

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 167 KB
• Volume: 14
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/s0957-4166(03)00455-5

✦ Synopsis

Chiral P,N-ferrocene ligands, 1-diphenylphosphino-1%-[(S)-4-isopropyl-2.5-oxazolinyl]-2%-(S p )-(trimethylsilyl)-ferrocene and its diastereomer, and 1-diphenylphosphino-1%-[(S)-4-isopropyl-2.5-oxazolinyl]-2%(S p )-(diphenylphosphino)-ferrocene and its diastereomer were used in the palladium-catalyzed asymmetric hydroesterification of styrene. The role of these ligands, which contain central, axial, and planar chirality, on the stereochemical outcome was investigated. A significant effect of using CuCl 2 as a co-catalyst on the reaction was observed. Excellent regioselectivity (b/n >99:1) with low ee (28%) was obtained in the presence of CuCl 2 ; moderate enantioselectivity (64% ee) but low regioselectivity (b/n, 40/60) was obtained in the absence of CuCl 2 .