Cavity-Directed Synthesis within a Self-Assembled Coordination Cage: Highly Selective [2 + 2] Cross-Photodimerization of Olefins
详细信息 查看全文
- 作者：Michito Yoshizawa ; Yoshihisa Takeyama ; Takashi Okano ; and Makoto Fujita
- 刊名：Journal of the American Chemical Society
- 出版年：2003
- 出版时间：March 19, 2003
- 年：2003
- 卷：125
- 期：11
- 页码：3243 - 3247
- 全文大小：118K
- 年卷期：v.125,no.11(March 19, 2003)
- ISSN：1520-5126
文摘
Herein reported is the highly selective [2 + 2] cross-photodimerization of olefins within a self-assembled coordination cage that acts as a molecular flask in an aqueous medium. An M6L4 coordinationnanocage that self-assembles from six Pd(II) complexes and four tridentate ligands accommodates twodifferent kinds of large olefin molecules such as acenaphthylene and 5-ethoxynaphthoquinone in a pairwiseselective fashion. This prerequisite recognition mode makes possible the selective [2 + 2] cross-photodimerization of the olefins within the cavity. The reaction is extremely efficient in terms of reactionrate, stereoselectivity, and, most importantly, pairwise selectivity. Maleimide derivatives, which themselvesare photochemically inactive under ordinary conditions, are also cross-dimerized with acenaphthylene ordibenzosuberenon quite efficiently. These results are in sharp contrast to those of common photodimerizationin organic media, where the yields and selectivities are generally poor to moderate. The key step of theexclusive formation of the cross-dimers stems from the selective formation of ternary complexes beforeirradiation, which is governed by the size compatibility of the guests with the confined space of the cavity.