Green Chemistry Blog

Recyclable mesoporous silica-supported chiral ruthenium-(NHC)NN-pincer catalysts for asymmetric reactions.  Scientists from Spain have reported two new stable chiral Ru-pincer complexes with a pendant silyloxy group, which were grafted onto a mesoporous silica (MCM-41).  These supported complexes were shown to be highly active and recyclable catalysts for the asymmetric hydrogenation of alkenes and the cyclopropanation of styrenes.  These catalysts avoid the draw-backs associated with homogeneous catalysts such as high catalyst loadings and difficulties in catalyst recovery.  The supported catalysts reported here showed no deactivation after repeated recycling. (Green Chem., 2011, DOI 10.1039/c1gc15412e)

C-H bond functionalisation with [RuH(codyl)₂]BF₄ catalyst precursor.  Scientists from the CNRS-University of Rennes, France have employed a ruthenium catalyst, assisted by a coordinating base, for the direct diarylation of arenes with (hetero)arylhalides.  This reaction under these conditions is milder that the classical organometallic cross-coupling reactions.  The coordinating ligand/base has an important role by promoting the initial cleavage of the C-H bond.  The efficiency of the system strongly depends on the nature of both the assisting ligand/base and the (hetero)aryl halides. (Green Chem., 2011, DOI: 10.1039/c1gc15642j)

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