9-Borabicyclo[3.3.2]decanes and the Asymmetric Hydroboration of 1,1-Disubstituted Alkenes

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• 作者：Ana Z. Gonzalez ; Jose&#x301 ; G. Roma&#x301 ; n ; Eduvigis Gonzalez ; Judith Martinez ; Jesus R. Medina ; Karl Matos ; John A. Soderquist
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：July 23, 2008
• 年：2008
• 卷：130
• 期：29
• 页码：9218 - 9219
• 全文大小：257K
• 年卷期：v.130,no.29(July 23, 2008)
• ISSN：1520-5126

文摘

The syntheses of the optically pure asymmetric hydroborating agents 1 (a, R = Ph; b, R = TMS) in both enantiomeric forms are reported. These reagents are effective for the hydroboration of cis-, trans- and trisubstituted alkenes. More significantly, they exhibit unprecedented levels of selectivity in the asymmetric hydroboration of 1,1-disubstituted alkenes (28−92% ee), a previously unanswered challenge in the nearly 50 year history of this reagent-controlled process. For example, the hydroboration of α-methylstyrene with 1a produces the corresponding alcohol 6f in 78% ee (cf., Ipc₂BH, 5% ee). Suzuki coupling of the intermediate adducts 5 produces the nonracemic products 7 very effectively (50−84%) without loss of optical purity.