Ruthenium-catalyzed step-growth

Synthesis of High-Molecular-Weight Pofymers by Ruthenium-Catalyzed Step-Growth Copolymerization of Acetophenones with a,cx -Dieiies... 

Two approaches are successful for the preparation of high molecular weight polymers by ruthenium catalyzed step-growth copolymerization... 

Oxidative photodegradation is a major problem for polymers which are utilized as coatings in exterior applications. Perfectly temating copolymers formed by ruthenium catalyzed step-growth copolymerization of acetophenones and a,co-dienes have considerable potential in this area. Thus, these polymers contain ortho alkyl acetophenone units as an integral part of the copolymer backbone. It is well known that... 

Acyclic diene metathesis (ADMET) is a step-growth polycondensation reaction for the polymerization of o -dienes 729 The process is catalyzed by the same metal alkylidene initiators used for ROMP, and is driven by the removal of ethylene from the system (Scheme 13). Both molybdenum and ruthenium-based initiators have been used to prepare a variety of materials including functionalized polyethy-... 

The new polymers 9-28 were synthesized by the Pd-catalyzed reaction of (4,4 - or 5,5 -dibromo-2,2 -bipyridine)-bis(4,4 -terf-butyl-2,2 -bipyridine or 2,2 -bipyridine)ruthenium(II) complexes 5-8 and diethynylarenes (Table 2) in a step-growth polycondensation mechanism (Scheme 4). The typical reaction conditions used for the synthesis of the polymers involved stirring the argon-... 

Woodgate et al. [51] applied the C-H/acetylene coupling to the ortho-selective alkenylation of terpene derivatives (Eq. 27). The basic feature of this reaction is the same as the alkenylation reaction of Murai et al. The combination of acetophenone and diynes provides a new entry for the copolymerization of aromatic ketones with acetylenes. Weber et al. [50] studied extensive reactions of ruthenium-catalyzed C-H/acetylene coupling with respect to the step-growth copolymerization of aromatic ketones and acetylenes (Eq. 28). These coupling reactions provide a new route to the preparation of trisubstituted styrene derivatives. 

Cyclothiazomycin is 1 of 76 structurally distinct actinomycete thio-peptide antibiotics, can inhibit bacterial protein synthesis, and prevent the growth of gram-positive bacteria [38]. In 2011, Deiters and cowor-kers reported their work on the synthesis of the pyridine core of cyclothiazomycin based on ruthenium-catalyzed [2 + 2 + 2] cyclotri-merization as the key step (Scheme 3.17) [39]. The electron-deficient nature of the thiazole-bearing nitrile enables ruthenium catalysis under mild reaction conditions with excellent yields. Complete chemo and regioselectivity in the construction of the trisubstituted pyridine core were achieved by applying a temporary silyl tether. 

Murai et al. have reported that dihydridocarbonyl/> /5(tiiphenylphosphine)ruthenium (Ru) catalyzes the addition of the ortho C-H bonds of acetophenone across the C-C double bonds of olefins such as trimethylvinylsilane to yield ortho alkyl substituted acetophenones (7-3). We have shown that this reaction can be applied to achieve step-growth copolymerization (cooligomerization) of aromatic ketones and a,co-dienes. For example, reaction of divinyldimethylsilane and acetophenone catalyzed by Ru at 150°C yields copoly(3,3-dimethyl-3-sila-1,5-pentanylene/2-aceto-1,3-phenylene), =... 

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