New, Highly Efficient Catalyst Precursors for Kharasch Additions − [RuCl(Cp*)(PPh3)2] and [RuCl(Ind)(PPh3)2]

Abstract

RuCl(Cp*)(PPh 3 ) 2 ] and [RuCl(Ind)(PPh 3 ) 2 ] are excellent catalyst precursors for promoting the Kharasch addition of CCl 4 and CHCl 3 across olefins under mild reaction conditions (at temperatures as low as 40°C with CCl 4 ). The effect of the substituents on the cyclopentadienyl ring has been investigated. In terms of efficiency and activity, [RuCl(Cp*)(PPh 3 ) 2 ][a]

Ruthenium Catalysts for the Kharasch Reaction

“…The addition of PPh 3 to the reaction mixture was found to reduce the rate of the reaction. It was therefore suggested that phosphine loss is required for the activation of the catalyst precursor 5 [20], similar to what has been proposed for complex 1 [11]. Variation of the phosphine ligand lead likewise to an reduced activity: upon substitution of the PPh 3 ligands of 5 with either tris(4-methoxyphenyl)phosphine or tris(4-trifluormethylphenyl)phosphine, the yields dropped significantly.…”

“…In a full report about this new type of catalyst, the related Cp-and (indenyl)Ru complexes 6 and 7 (Fig. 4) were included [20]. For all reactions investigated, the CpRu complex 6 gave lower yields than the complexes 5 and 7.…”

“…For the addition of CCl 4 to styrene, for example, a yield of 69 % was obtained after only 6 h at 40 °C using 0.33 mol% of the catalyst precursor 5 or 7 ( Table 1, entry 1 and 2). Under identical conditions, only 16 % of the adduct was observed for the Ru phosphine catalyst 1 ( Table 1, entry 3) [20]. With complex 5, it was even possible to perform the reaction at room temperature with excellent yields ( Table 1, entry 4).…”

“…The complexes 5 and 7 are also efficient catalysts for the addition of CCl 4 to acrylates for which a quantitative monoadduct formation was observed after a few hours. With 1-decene as the olefinic substrate, however, a yield of only 27 % (24 h, 60 °C) was observed for reactions with the Cp* complex 5 and a yield of 45 % was found for the indenyl complex 7 [20]. Here, the 'classical' ruthenium complex [RuCl 2 (PPh 3 ) 3 ] (1) gave superior results.…”

Immobilized metal ion-containing ionic liquids: Preparation, structure and catalytic performances in Kharasch addition reaction and Suzuki cross-coupling reactions

“…Kharasch et al reported the addition of carbon tetrachloride or chloroform to C=C double bond of alkenes in the presence of peroxide [22]. The Kharasch reactions have been studied in homogeneous systems by using iron and copper chlorides [23][24][25][26], ruthenium complexes [27][28][29][30], palladium complex [31], nickel pincer complex [32,33], rhodium-ruthenium bimetallic complex [34], and Eu(OTf) 3 [35].…”