Blanco Christian O, Nascimento Daniel L, Fogg Deryn E
Center for Catalysis Research & Innovation and Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway.
Organometallics. 2021 Jun 28;40(12):1811-1816. doi: 10.1021/acs.organomet.1c00253. Epub 2021 Jun 16.
Clean, high-yielding routes are described to ruthenium-diiodide catalysts that were recently shown to enable high productivity in olefin metathesis. For the second-generation Grubbs and Hoveyda catalysts (: RuCl(HIMes)(PCy)(=CHPh); : RuCl(HIMes)(=CHAr), Ar = CH-2-O Pr), slow salt metathesis is shown to arise from the low lability of the ancillary PCy or ether ligands, which retards access to the four-coordinate intermediate required for efficient halide exchange. To exploit the lability of the first-generation catalysts, the diiodide complex RuI(PCy)(=CHAr) was prepared by treating "Grubbs I" (RuCl(PCy)(=CHPh), ) with NaI, HC=CHAr (), and a phosphine-scavenging Merrifield iodide () resin. Subsequent installation of HIMes or cyclic (alkyl)(amino)carbene (CAAC) ligands afforded the second-generation iodide catalysts in good to excellent yields. Given the incompatibility of the nitro group with a free carbene, the iodo-Grela catalyst RuI(HIMes)(=CHAr') ( : Ar' = CH-2-O Pr-4-NO) was instead accessed by sequential salt metathesis of with NaI, installation of HIMes, and finally cross-metathesis with the nitrostyrenyl ether HC=CHAr' (), with as the phosphine scavenger. The bulky iodide ligands improve the selectivity for macrocyclization in ring-closing metathesis.
本文描述了清洁、高产率的路线来制备二碘化钌催化剂，这些催化剂最近被证明能在烯烃复分解反应中实现高生产率。对于第二代格拉布斯催化剂和霍维达催化剂（：RuCl(HIMes)(PCy)(=CHPh)；：RuCl(HIMes)(=CHAr)，Ar = CH-2-O Pr），慢盐复分解反应源于辅助的PCy或醚配体的低活性，这阻碍了生成高效卤化物交换所需的四配位中间体。为了利用第一代催化剂的活性，通过用NaI、HC=CHAr（）和一种清除膦的 Merrifield 碘化物（）树脂处理“格拉布斯I”（RuCl(PCy)(=CHPh)，）制备了二碘化物配合物RuI(PCy)(=CHAr) 。随后安装HIMes或环（烷基）（氨基）卡宾（CAAC）配体，以良好至优异的产率得到第二代碘化物催化剂。鉴于硝基与游离卡宾不相容，碘代 - 格雷拉催化剂RuI(HIMes)(=CHAr')（ ：Ar' = CH-2-O Pr-4-NO）则通过与NaI进行连续盐复分解反应、安装HIMes，最后与硝基苯乙烯基醚HC=CHAr'（）进行交叉复分解反应来制备，其中 作为膦清除剂。庞大的碘化物配体提高了闭环复分解反应中环化的选择性。
