Department of Chemistry and Biotechnology, School of Engineering, and Department of Materials Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
Nanomaterials Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.
J Am Chem Soc. 2023 Jun 7;145(22):12059-12065. doi: 10.1021/jacs.3c01225. Epub 2023 May 24.
Topochemical reactions provide selective products based on the molecular position; however, they generally require molecules to be placed in strictly limited orientations and distances, making them less versatile. In this study, we found that by confining -4-styrylpyridine (4-spy) as a reactive substrate in a flexible metal-organic framework (MOF) nanospace, [2+2] cycloadducts can be selectively obtained, even when the distance between two C═C bonds of 4-spy in the crystal is 5.9 Å, which is much larger than the conventionally observed upper limit (4.2 Å). Such an unusual cyclization reaction is suggested to occur due to the transient proximity of the 4-spy due to the "swing" motion in the nanospace. The MOF nanospace, with its high degree of molecular structural freedom, can be applied to different platforms that do not require the fine constraints of reactive distances for solid-phase reactions.
拓扑化学反应可根据分子位置提供选择性产物；然而，它们通常需要将分子严格限制在特定的取向和距离内，因此不够灵活。在这项研究中，我们发现通过将 -4- 乙烯基吡啶（4-spy）作为反应性底物限制在柔性金属有机骨架（MOF）纳米空间中，可以选择性地获得 [2+2] 环加成产物，即使在晶体中 4-spy 的两个 C═C 键之间的距离为 5.9 Å 时也是如此，这远大于通常观察到的上限（4.2 Å）。这种不寻常的环化反应是由于在纳米空间中“摆动”运动导致 4-spy 的瞬时接近而发生的。MOF 纳米空间具有高度的分子结构自由度，可以应用于不同的平台，而不需要固相反应中对反应距离的严格限制。
