Stereochemistry and mechanistic study of intramolecular Pd(II)-catalyzed oxypalladation and 1,3-chirality-transfer reactions.
Stereochemistry and mechanistic study of intramolecular Pd(II)-catalyzed oxypalladation and 1,3-chirality-transfer reactions.
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DOI：
10.1002/asia.200700390
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
J. Uenishi;Y. Vikhe;N. Kawai
中科院分区：
文献类型：
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作者：
J. Uenishi;Y. Vikhe;N. Kawai
描述了手性α-、ζ-和η-羟基-α，β-不饱和醇的Pd（II）催化的环化。反应立体专一地进行，分别得到手性2，5-二取代四氢呋喃、2，6-二取代四氢吡喃和2，7-二取代氧杂环庚烷。手性烯丙醇的碳中心的手性立体特异性地转移到新生成的氧杂环的碳中心。一个合理的反应机理包括1）手性烯丙醇诱导的Pd π-络合物的顺式选择性形成，2）顺式氧钯化，和3）PdCl（OH）的顺式消除，这为立体化学结果提供了合理的解释。
Pd(II)-catalyzed cyclizations of chiral epsilon-, zeta-, and eta-hydroxy-alpha,beta-unsaturated alcohols are described. The reactions took place stereospecifically to give chiral 2,5-disubstituted tetrahydrofurans, 2,6-disubstituted tetrahydropyrans, and 2,7-disubstituted oxepanes, respectively. The chirality of the carbon center of the chiral allylic alcohol is transferred stereospecifically to the carbon center of the newly generated oxacyclic ring. A plausible reaction mechanism involves 1) chiral-allylic-alcohol-induced syn facioselective formation of a Pd pi-complex, 2) syn oxypalladation, and 3) syn elimination of PdCl(OH), which provide a rational account for the stereochemical results.