9-borabicyclo[3.3.2]decanes and the asymmetric hydroboration of 1,1-disubstituted alkenes
9-borabicyclo[3.3.2]decanes and the asymmetric hydroboration of 1,1-disubstituted alkenes
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DOI：
10.1021/ja803119p
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发表时间：
2008-07-23
影响因子：
15
通讯作者：
Soderquist, John A.
中科院分区：
文献类型：
--
作者：
Gonzalez, Ana Z.;Roman, Jose G.;Soderquist, John A.
报道了两种光学纯的不对称硼氢化试剂1（a，R = Ph; B，R = TMS）的合成。这些试剂对于顺式、反式和三取代烯烃的硼氢化反应是有效的。更重要的是，它们在1，11-二取代烯烃的不对称硼氢化反应中表现出前所未有的选择性水平（28- 92%ee），这是该试剂控制工艺近50年历史中以前未回答的挑战。例如，α-甲基苯乙烯与1a的硼氢化反应产生78%ee的相应醇6 f（参见，Ipc（2）BH，5%ee）。中间体加合物5的Suzuki偶联非常有效地（50-84%）产生非外消旋产物7，而不损失光学纯度。
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 1,11-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 alpha-methylstyrene with 1a produces the corresponding alcohol 6f in 78% ee (cf., Ipc(2)BH, 5% ee). Suzuki coupling of the intermediate adducts 5 produces the nonracemic products 7 very effectively (50-84%) without loss of optical purity.