Borabicyclo[3.3.2]decanes and the Stereoselective Asymmetric Synthesis of 1,3-Diol Stereotriads from 1,3-Diborylpropenes
Borabicyclo[3.3.2]decanes and the Stereoselective Asymmetric Synthesis of 1,3-Diol Stereotriads from 1,3-Diborylpropenes
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DOI：
10.1021/ja808360z
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发表时间：
2009-01-28
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.
描述了混合硼二环环烷 (BBD) 衍生的 1,3-二硼基丙烯 (trans-1) 的合成。这些新的双金属试剂对于酮（或酮亚胺）和醛（或醛亚胺）的选择性不对称烯丙基硼化是有效的。作为反式区域异构体的热力学混合物，由 cis-1 通过一系列 1,3-硼致硼位移形成，只有 trans-1 经历酮的单烯丙基化。在这一次添加之后，该过程在 1 中的 10-Ph-9-BBD 部分反应后有效地停止。作为分子门，重排的 10-TMS-9-BBD 反式烯丙基硼烷中间体 11 仅在添加醛（或醛亚胺）后才发生反应。这种烯丙基化固定了 2-乙烯基-1,3-二醇立体三联体的最后两个立体中心，最终产生 16（或 1,3-氨基醇），产率为 50-72%（> 98% ee），为单一可观察到的非对映异构体。这些试剂 1 的独特功能相当于 1,1-双金属烯丙基试剂，依次首先添加到酮中，然后添加到醛中。
The synthesis of mixed borabicycloclecane (BBD)-derived 1,3-diborylpropenes (trans-1) is described. These new bimetallic reagents are effective for the selective asymmetric allylboration first of ketones (or ketimines) and second of aldehydes (or aldimines). Formed as a thermodynamic mixture of trans regioisomers from cis-1 through a series of 1,3-borotropic shifts, only trans-1 undergoes the monoallylation of ketones. After this single addition, this process is effectively shut down after the reaction of the 10-Ph-9-BBD portion in 1. Serving as a molecular gate, the rearranged 10-TMS-9-BBD transallylborane intermediate 11 reacts only after an aldehyde (or aldimine) is added. This allylation fixes the last two stereogenic centers of the 2-vinyl-1,3-diol stereotriad, ultimately resulting in 16 (or 1,3-amino alcohols) in 50-72% yield (> 98% ee) as single observable diastereomers. These reagents 1 uniquely function as the equivalent of 1,1-bimetallic allylic reagents, adding sequentially first to ketones and second to aldehydes.