Self-assembled poly(imidazole-palladium): highly active, reusable catalyst at parts per million to parts per billion levels.
Self-assembled poly(imidazole-palladium): highly active, reusable catalyst at parts per million to parts per billion levels.
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DOI：
10.1021/ja210772v
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发表时间：
2012-02
影响因子：
15
通讯作者：
Yoichi M. A. Yamada;S. Sarkar;Y. Uozumi
中科院分区：
文献类型：
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作者：
Yoichi M. A. Yamada;S. Sarkar;Y. Uozumi
金属酶是重要的蛋白质，具有促进高效酶反应的重要活性。为了确保安全、无毒、可持续的化学合成和绿色有机合成的催化活性、稳定性和可重复使用，开发金属酶激发的聚合物负载金属催化剂具有重要意义。在这里，我们提出了一种高活性、可重复使用的、受金属酶激发的聚咪唑-丙烯酰胺和钯物种的自组装催化剂，并将我们的卷积方法应用于制备聚合物金属催化剂。因此，通过(NH4)(2)PdCl4与poly[(N-vinylimidazole)-co-(N-isopropylacrylamide)(5)]在80℃的甲醇-水溶液中络合卷积30min，可以容易地制备出金属酶激发的聚合物咪唑钯催化剂(MEPI-Pd)。扫描电子显微镜观察表明，MEPI-Pd具有球状聚集的自组装结构。透射电子显微镜观察、XPS和EDX分析表明，PdCl(2)和Pd(0)纳米粒子均匀分散在MEPI-Pd中。将MEPI-Pd用于烯丙基酯和碳酸酯与芳基/烯基硼酸、乙烯基硼酸酯和四芳基硼酸酯的烯丙基芳基化/烯基化/乙烯基化反应。即使0.8-40molppmPd的MEPI-Pd也能有效地促进醇和/或水中的烯丙基芳基化/烯烃/乙烯基化反应，其催化周转数(TON)为20,000-1,250,000。此外，MEPI-Pd有效地促进了各种灭活的芳基氯化物以及芳基溴和碘在高达3,570,000吨的水中的Suzuki-Miyaura反应。在不损失催化活性的情况下，MEPI-Pd重复用于芳基氯的烯丙基芳基化和Suzuki-Miyaura反应。
Metalloenzymes are essential proteins with vital activity that promote high-efficiency enzymatic reactions. To ensure catalytic activity, stability, and reusability for safe, nontoxic, sustainable chemistry, and green organic synthesis, it is important to develop metalloenzyme-inspired polymer-supported metal catalysts. Here, we present a highly active, reusable, self-assembled catalyst of poly(imidazole-acrylamide) and palladium species inspired by metalloenzymes and apply our convolution methodology to the preparation of polymeric metal catalysts. Thus, a metalloenzyme-inspired polymeric imidazole Pd catalyst (MEPI-Pd) was readily prepared by the coordinative convolution of (NH(4))(2)PdCl(4) and poly[(N-vinylimidazole)-co-(N-isopropylacrylamide)(5)] in a methanol-water solution at 80 °C for 30 min. SEM observation revealed that MEPI-Pd has a globular-aggregated, self-assembled structure. TEM observation and XPS and EDX analyses indicated that PdCl(2) and Pd(0) nanoparticles were uniformly dispersed in MEPI-Pd. MEPI-Pd was utilized for the allylic arylation/alkenylation/vinylation of allylic esters and carbonates with aryl/alkenylboronic acids, vinylboronic acid esters, and tetraaryl borates. Even 0.8-40 mol ppm Pd of MEPI-Pd efficiently promoted allylic arylation/alkenylation/vinylation in alcohol and/or water with a catalytic turnover number (TON) of 20,000-1,250,000. Furthermore, MEPI-Pd efficiently promoted the Suzuki-Miyaura reaction of a variety of inactivated aryl chlorides as well as aryl bromides and iodides in water with a TON of up to 3,570,000. MEPI-Pd was reused for the allylic arylation and Suzuki-Miyaura reaction of an aryl chloride without loss of catalytic activity.