Hata Hiroshi, Yamaguchi Shigeru, Mori Goro, Nakazono Satomi, Katoh Taisuke, Takatsu Keishi, Hiroto Satoru, Shinokubo Hiroshi, Osuka Atsuhiro
Department of Chemistry, Graduate School of Science, Kyoto University, PRESTO & CREST, Japan Science and Technology Agency, Sakyo-ku, Kyoto 606-8502, Japan.
Chem Asian J. 2007 Jul 2;2(7):849-59. doi: 10.1002/asia.200700086.
Highly regioselective and efficient borylation of a variety of porphyrins has been achieved by reaction with bis(pinacolato)diboron through C-H bond activation under iridium catalysis on the basis of the synthetic protocol developed by Miyaura, Hartwig, and Smith. A boryl group can be selectively introduced at sterically uncongested positions in the peripheral aryl groups of porphyrin substrates whose peripheral beta-positions are sterically hindered. Curiously, beta substituents adjacent to the aryl group to be borylated have unexpectedly large effects on the regioselectivity, because the iridium catalyst can discriminate between subtle steric differences. Chemoselective borylation was also achieved for several functionalized porphyrins. This borylation protocol can be applied to various monomeric and oligomeric functional porphyrins, hence offering an efficient route to elaborate multiporphyrin-based molecular constructs.
基于宫浦、哈特维希和史密斯开发的合成方案，通过在铱催化下与双（频哪醇合）二硼反应，经C-H键活化实现了多种卟啉的高度区域选择性和高效硼化反应。在卟啉底物外围芳基中空间位阻较小的位置，可以选择性地引入一个硼基，其外围β位存在空间位阻。奇怪的是，与要硼化的芳基相邻的β取代基对区域选择性有着意想不到的巨大影响，这是因为铱催化剂能够区分细微的空间差异。对于几种功能化卟啉也实现了化学选择性硼化。这种硼化方案可应用于各种单体和低聚功能卟啉，从而为构建复杂的基于多卟啉的分子结构提供了一条有效途径。
