Highly active ruthenium metathesis catalysts enabling ring-opening metathesis polymerization of cyclopentadiene at low temperatures

Abstract

Development of versatile ruthenium olefin-metathesis catalysts with high activity, stability, and selectivity is a continuous challenge. Here we report highly controllable ruthenium catalysts using readily accessible and versatile N -vinylsulfonamides as carbene precursors. Catalyst initiation rates were controlled in a straightforward manner, from latent to fast initiating, through the facile modulation of the N -vinylsulfonamide ligands. Trifluoromethanesulfonamide-based catalysts initiated ultrarapidly even at temperatures as low as −60 °C and continuously propagated rapidly, enabling the enthalpically and entropically less-favored ring-opening metathesis polymerizations of low-strained functionalized cyclopentene derivatives, some of which are not accessible with previous olefin-metathesis catalysts. To our surprise, the developed catalysts facilitated the polymerization of cyclopentadiene (CPD), a feedstock that is easily and commonly obtainable through the steam cracking of naphtha, which has, to the best of our knowledge, not been previously achieved due to its low ring strain and facile dimerization even at low temperatures (below 0 °C).

Degradable Polyphosphoramidate via Ring-Opening Metathesis Polymerization

“…ROMP is known as a powerful tool for the synthesis of polymers with predictable molecular weights, narrow molecular weight distributions, and complex architectures. − In particular, the development of well-defined ruthenium carbene initiators has enabled efficient polymerization with excellent functional group tolerance. − Despite the tremendous diversity of functional nondegradable polymers accessed via ROMP, − examples of well-defined high molecular weight polymers consisting of fully degradable backbones remain rare. In 2013, Kiessling and co-workers demonstrated the controlled ROMP of bicyclic oxazinones, resulting in polymers that degrade under both acidic and basic conditions .…”

“…However, an evaluation of the ring strain energy of PTDO via a density functional theory calculation revealed a low ring strain of 10.86 kcal/mol (Figure S1). This number is markedly lower than the strain energy of norbornene (27.2 kcal/mol), the most widely used monomer class employed for ROMP. , In the case of low ring strain monomers such as cyclopentene, one approach to achieve high monomer conversion is to lower the reaction temperature. ,− Therefore, we hypothesized that ROMP of PTDO would be achieved at low reaction temperatures to afford polymers with controlled molecular weight and low dispersity. Furthermore, upon hydrolysis, the polymer would degrade into a phosphoric acid and 1,4-diamino-2-butene, which is an unsaturated analog of biogenic amines involved in cell growth and differentiation, leading to a potentially biocompatible material …”

Glycoengineering of NK Cells with Glycan Ligands of CD22 and Selectins for B‐Cell Lymphoma Therapy

“…Both cell lines possess complex type N ‐glycans terminated with N ‐acetyllactosamine (type 2 Lac N Ac Galβ1‐4Glc N Ac, or in the case of HEK293 also minor amounts of LacDi N Ac, Gal N Acβ1‐4Glc N Ac) as is the case for most mammalian cells. Two α2‐6STs, the truncated human ST6Gal1 [33] and Photobacterium damsela 2,6ST (Pd2,6ST [34, 35] ), were evaluated for this endeavor using biotinylated CMP‐Neu5Ac [36] as the donor. Approximately 2fold more biotin‐Neu5Ac was incorporated onto Lec2 cells by ST6Gal1 compared to that added by Pd2,6ST (Supplementary Figure s1).…”

PEG/PPG-PDMS-Adamantane-Based Crosslinked Terpolymer Using the ROMP Technique to Prepare a Highly Permeable and CO2-Selective Polymer Membrane

“…Furthermore, a crosslinking method using ROMP was employed for polymerization to improve the physical properties of the rubbery polymers mentioned above. ROMP has the advantage of easy post-modification after polymer synthesis using various monomers with different functional groups [ 24 , 25 , 26 , 27 , 28 , 29 ].…”