Isoxazole-directed pinacol rearrangement: stereocontrolled approach to angular stereogenic centers.
Isoxazole-directed pinacol rearrangement: stereocontrolled approach to angular stereogenic centers.
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DOI：
10.1002/anie.200605138
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发表时间：
2007-04
影响因子：
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通讯作者：
Keisuke Suzuki;H. Takikawa;Y. Hachisu;J. Bode
中科院分区：
文献类型：
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作者：
Keisuke Suzuki;H. Takikawa;Y. Hachisu;J. Bode
在我们对一些聚酮类天然产物的合成研究中，包括seragakinoneA(1)[1]和抗生素BE-43472A(2),[1]，我们需要一种通用而有效的方法来在这些多环化合物的角位置建立四元立体中心（方案1）。认识到传统的立体控制构建季碳中心的策略，例如，烯醇烷基化和亲核置换反应，[3]不能提供这个问题的一般解决方案，我们设想通过三环二醇I的pinacol重排可以间接但有效地获得角取代酮II（方案2）。必须满足两个关键要求：1)二醇I需要以立体定义的形式容易获得，2)1,2移位必须以区域选择性和立体特异性的方式发生。后一个标准是有挑战性的，因为两个羟基
In our synthetic studies towards some polyketide-derived natural products, including seragakinoneA (1)[1] and the antibiotic BE-43472A (2),[2] we required a general and effective method for establishing quaternary stereogenic centers at the angular position in these polycyclic compounds (Scheme 1). With the recognition that conventional strategies for the stereocontrolled construction of quaternary carbon centers, for example, enolate alkylation and nucleophilic displacement reactions,[3] would not provide a general solution to this problem, we envisaged that an indirect but efficient route to the angularly substituted ketone II would be available by the pinacol rearrangement of the tricyclic diol I (Scheme 2).[4]For such a scenario to be feasible, however, two critical requirements must be fulfilled: 1) The diol I needs to be readily available in a stereodefined form, and 2) the 1, 2-shift must occur in a regioselective and stereospecific manner. The latter criterion is challenging, because the two hydroxy groups