Metallodendritic Catalysis for Redox and CarbonCarbon Bond Formation Reactions: A Step towards Green Chemistry.

Abstract

Metallodendritic catalysts combine the advantages of homogeneous and heterogeneous catalysts: they are soluble and perfectly well defined on the molecular level, and yet they can be recovered by precipitation, ultra-filtration or ultra-centrifugation (as biomolecules) and recycled several times. In this article, we summarize our recent work in this field with examples operating under ambient conditions in metathesis, Pd-catalyzed Sonogashira coupling, redox catalysis of nitrate and nitrite cathodic reduction to ammonia and various oxidation reactions by H 2 O 2 catalyzed by polyoxometallates. The dendritic effects on the catalytic efficiencies are scrutinized, i.e., the comparison of the metallodentritic catalysts with their monomeric models and among the dendrimer generations. It is concluded that metallostars or low-generation metallodendrimers usually are optimized catalysts in terms of efficiency and recovery/re-use.

Organoiron-mediated dendrimer syntheses with 1→3 connectivity and applications

“…This strategy was also applied to related fully polyoxometalate (POM)-centered dendrimers. [119][120][121][122] Functionalizaton of olefin-terminated dendrimers by hydrosilylation reactions using chlorosilanes has been achieved in particular in van Leeuwen's divergent dendrimer synthesis 123 and using chloromethyldimethylsilane by Seyferth, both with 1/2 connectivity. 58 Chlorodimethylsilane could also be used for a direct one-pot iterative dendrimer synthesis with 1/3-connectivity up to G3-243-allyl.…”

Synthesis and studies of pyrazolo[3,4-b]piperidin-4-one derivatives

“…The reaction between benzaldehyde, aniline and cyclohexanone as a model reaction in water in the presence of various amounts of first generation dendrimer [6][7][8][9][10][11][12][13][14]. It was found that only 2 mol % of the catalyst was required to drive the reaction smoothly to completion.…”

Role of cluster size and substrate in the gas phase CC bond coupling reactions of allyl halides mediated by Agn+ and Agn−1H+ cluster cations

“…Despite decades of use, there is still much interest in developing new approaches for C C bond coupling, and recent attention has focussed on a range of areas including the development of new catalysts [4], design of water based organometallics [5] and the use of metallic nanoparticles [6]. One of the most widely studied classes of C C bond coupling reactions are metal mediated reductive coupling of organohalides, the so called "Wurtz" reaction [7].…”