Chloro({2-[mesityl(quinolin-8-yl-κN)boryl]-3,5-dimethyl-phenyl}methyl-κC)palladium(II) as a Catalyst for Heck Reactions

Abstract

Abstract:We recently reported an air and moisture stable 16-electron borapalladacycle formed upon combination of 8-quinolyldimesitylborane with bis(benzonitrile)dichloropalladium(II). The complex features a tucked mesityl group formed upon metalation of an ortho-methyl group on a mesityl; however it is unusually stable due to contribution of the boron pz orbital in delocalizing the carbanion that gives rise to an η 4 -boratabutadiene fragment coordinated to Pd(II), as evidenced from crystallographic data. This complex was observed to be a highly active catalyst for the Heck reaction. Data of the catalyst activity are presented alongside data found in the literature, and initial comparison reveals that the borapalladacycle is quite active. The observed catalysis suggests the borapalladacycle readily undergoes reductive elimination; however the Pd(0) complex has not yet been isolated. Nevertheless, the ambiphilic ligand 8-quinolyldimesitylborane may be able to support palladium in different redox states.

Study of Pd-based catalysts within red algae-derived polysaccharide supports in a Suzuki cross-coupling reaction

“…Thus, the low solubilities of arylhalides in water as well as the low solubility of phenylbronic acid and inorganic base in apolar organic solvents, have led to the use of hazardous polar organic solvents such as DMF and DMSO as reaction media. 46 The investigation initiated with the homogenous crosscoupling of iodobenzene and phenylboronic acid ( Fig. 1) with several simple and commercial available palladium catalysts in ethanol ( Table 1, entries 1-4).…”

Recent Advances in Palladium‐Catalyzed Cross‐Coupling Reactions at ppm to ppb Molar Catalyst Loadings

“…The Xiao group described the use of an N,C,N‐tridentate carbene ligand in a Heck reaction; during their examination of the scope of the reaction of aryl iodides, the catalyst loading was decreased to 1 mol ppm, and this afforded 78% conversion. Tamang and Hoefelmeyer synthesized an unusual complex in which nitrogen and boron atoms and an allyl group were coordinated to the palladium center; this was successfully used in the Heck reaction of iodobenzene with butyl acrylate at a catalyst loading of 10 mol ppm. Frech and co‐workers developed a P,C,P‐tridentate pincer complex .…”

Recyclable Pd‐based polysaccharide catalyst for aerobic oxidation of benzyl alcohol

“…The addition of phosphine ligands, like triphenyl phosphine (TPP), to the palladium salt can stabilize the metallic center and thus prevent catalyst deactivation. 30,31 To that end, Pd(OAc) 2 (TPP) 2 was also tested in the three solvents without or with the addition of sodium carbonate (Table 1, entries 3 and 4, respectively). The highest conversion was detected in ethyl acetate, which can be attributed to the change in the solubility of the complex compared to that of the palladium salt.…”