A Standard System of Characterization for Olefin Metathesis Catalysts

Abstract

The success of olefin metathesis has spurred the intense investigation of new catalysts for this transformation. With the development of many different catalysts, however, it becomes increasingly difficult to compare their efficiencies. In this article we introduce a set of six reactions with specific reaction conditions to establish a standard for catalyst comparison in olefin metathesis. The reactions were selected on the basis of their ability to provide a maximum amount of information describing catalyst activity, stability, and selectivity, while being operationally simple. Seven of the most widely used rutheniumbased olefin metathesis catalysts were evaluated with these standard screens. This standard is a useful tool for the comparison and evaluation of new metathesis catalysts.

Synthesis and study of olefin metathesis catalysts supported by redox-switchable diaminocarbene[3]ferrocenophanes

“…Although catalytic activity was not observed under the standardized conditions reported by Grubbs and co-workers (CD 2 Cl 2 , 30°C), 61 enhanced activities were observed at 80°C in toluene. …”

Origins of Initiation Rate Differences in Ruthenium Olefin Metathesis Catalysts Containing Chelating Benzylidenes

“…The resulting biphasic reaction mixture was stirred at 65 °C for 48 h. The flask was allowed to cool to room temperature, and 25% (aq.) NH 4 OAc solution (10 mL) was added to partition the mixture. The phases were separated, and the aqueous phase was further extracted with Et 2 O (2 × 100 mL).…”

“…TBAF (1.0 M in THF) solution (7.6 mL, 7.6 mmol) was added, and the solution was allowed to stir at room temperature for 90 min. The reaction was quenched with 25% NH 4 OAc solution (50 mL) and was extracted with EtOAc (3 × 50 mL). The combined organic layers were washed with brine (100 mL), dried over Na 2 SO 4 , filtered, and concentrated in vacuo.…”

Synthesis and Reactivity of Olefin Metathesis Catalysts Bearing Cyclic (Alkyl)(Amino)Carbenes

“…These results are consistent with those obtained previously with pyridine-containing catalysts. [19] For comparison, complexes 2 and 3 can achieve 95% conversion to 10 in 30 and 20 min, respectively, at 30°C and 1 mol % catalyst loading. [19] To obtain more stable complexes, we targeted complexes 12a,b.…”

“…[19] For comparison, complexes 2 and 3 can achieve 95% conversion to 10 in 30 and 20 min, respectively, at 30°C and 1 mol % catalyst loading. [19] To obtain more stable complexes, we targeted complexes 12a,b. After addition of 5 a,b (prepared in situ) to ruthenium precursor 11, [8] catalysts 12a,b were isolated and purified in good yields by column chromatography [Eq.…”