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Olefin Metathesis in Confinement: Towards Covalent Organic Framework Scaffolds for Increased Macrocyclization Selectivity
Author(s) -
Emmerling Sebastian T.,
Ziegler Felix,
Fischer Felix R.,
Schoch Roland,
Bauer Matthias,
Plietker Bernd,
Buchmeiser Michael R.,
Lotsch Bettina V.
Publication year - 2022
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202104108
Subject(s) - selectivity , catalysis , metathesis , covalent organic framework , covalent bond , heterogeneous catalysis , olefin fiber , chemical engineering , chemistry , materials science , combinatorial chemistry , organic chemistry , polymerization , polymer , engineering
Covalent organic frameworks (COFs) offer vast structural and chemical diversity enabling a wide and growing range of applications. While COFs are well‐established as heterogeneous catalysts, so far, their high and ordered porosity has scarcely been utilized to its full potential when it comes to spatially confined reactions in COF pores to alter the outcome of reactions. Here, we present a highly porous and crystalline, large‐pore COF as catalytic support in α,ω‐diene ring‐closing metathesis reactions, leading to increased macrocyclization selectivity. COF pore‐wall modification by immobilization of a Grubbs‐Hoveyda‐type catalyst via a mild silylation reaction provides a molecularly precise heterogeneous olefin metathesis catalyst. An increased macro(mono)cyclization (MMC) selectivity over oligomerization (O) for the heterogeneous COF‐catalyst (MMC:O=1.35) of up to 51 % compared to the homogeneous catalyst (MMC:O=0.90) was observed along with a substrate‐size dependency in selectivity, pointing to diffusion limitations induced by the pore confinement.