Highly stereoselective photocyclodimerization of α-cyclodextrin-appended anthracene mediated by γ-cyclodextrin and cucurbit[8]uril:: A dramatic steric effect operating outside the binding site
Highly stereoselective photocyclodimerization of α-cyclodextrin-appended anthracene mediated by γ-cyclodextrin and cucurbit[8]uril:: A dramatic steric effect operating outside the binding site
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DOI：
10.1021/ja8032923
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发表时间：
2008-07-09
影响因子：
15
通讯作者：
Inoue, Yoshihisa
中科院分区：
文献类型：
--
作者：
Yang, Cheng;Mori, Tadashi;Inoue, Yoshihisa
研究了α-环糊精(Cd)与环糊精(Cucurbit[8]，CB[8])在γ-CD和Cucurbit[8]底物存在下的光环二聚反应，以操纵腔内通过位于腔外的大量附着体进行的立体区分光反应。在γ-Cd介导的光二聚反应中，得到了头到尾的光二聚体，总产率为98%，特别是头到尾的合成的光二聚体的产率为91%，产率为68%，远高于未修饰的蒽羧酸盐获得的32%的ee和44%的产率。CB[8]的使用还导致了头对尾/头对头选择性的显著反转，仅提供了头对头的光电二聚体，总收率为99%。
Photocyclodimerization of alpha-cyclodextrin (CD)-appended anthracene was studied in the presence of gamma-CD and cucurbit[8] uril (CB[8]) hosts to manipulate the stereodifferentiating photoreaction occurring inside the cavity by the bulky attachment located outside. The gamma-CD-mediated photodimerization afforded the head-to-tail photodimers in 98% combined yield, in particular, the syn-head-to-tail photodimer of 91% ee in 68% yield, which are much greater than 32% ee and 44% yield obtained with unmodified anthracene carboxylate. The use of CB[8] also led to a striking inversion of the head-to-tail/head-to-head selectivity, affording exclusively the head-to-head photodimers in 99% combined yield.