Department of Natural Sciences, Mid Sweden University, Sundsvall, SE-85170, Sweden.
Berzelii Center EXSELENT on Porous Materials, Stockholm University, Stockholm, SE-10691, Sweden.
Sci Rep. 2020 Apr 14;10(1):6407. doi: 10.1038/s41598-020-63083-8.
A new eco-friendly approach for the preparation of sustainable heterogeneous palladium catalysts from rice husk-derived biogenic silica (RH-Si and RH-Si). The designed heterogeneously supported palladium species (RH-Si-NH-Pd and RH-Si-NH-Pd) were fully characterized and successfully employed as catalysts for various chemical transformations (C-C bond-forming reactions, aerobic oxidations and carbocyclizations). Suzuki-Miyaura transformations were highly efficient in a green solvent system (HO:EtOH (1:1) with excellent recyclability, providing the cross-coupling products with a wide range of functionalities in high isolated yields (up to 99%). Palladium species (Pd(0)-nanoparticles or Pd(II)) were also efficient catalysts in the green aerobic oxidation of an allylic alcohol and a co-catalytic stereoselective cascade carbocyclization transformation. In the latter case, a quaternary stereocenter was formed with excellent stereoselectivity (up to 27:1 dr).
一种从稻壳衍生的生物成因硅（RH-Si 和 RH-Si）制备可持续的非均相钯催化剂的新型环保方法。设计的非均相负载钯物种（RH-Si-NH-Pd 和 RH-Si-NH-Pd）进行了充分的表征，并成功用作各种化学转化（C-C 键形成反应、有氧氧化和碳环化）的催化剂。Suzuki-Miyaura 转化在绿色溶剂体系（HO:EtOH（1:1））中非常高效，具有出色的可回收性，提供了具有广泛官能团的交叉偶联产物，收率高（高达 99%）。钯物种（Pd(0)-纳米粒子或 Pd(II)）也是烯丙醇有氧氧化和协同立体选择性级联碳环化转化的有效催化剂。在后一种情况下，形成了具有出色立体选择性的季立体中心（高达 27:1 dr）。
