Angewandte Chemie International Edition
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Inside Cover: Highly Selective Metal Catalysts for Intermolecular Carbenoid Insertion into Primary C-H Bonds and Enantioselective C-C Bond Formation (Angew. Chem. Int. Ed. 50/2008)
Analogous to a microreactor that has twelve inlets, but with only one large enough for secondary C-H bonds to approach reactive metal–carbene groups, a rhodium catalyst bearing a bis-pocket porphyrin that imposes a high steric hindrance to secondary C-H bonds is described by C.-M. Che et al. in their Communication on page 9747 ff. The porphyrin directs reactions to occur at the less reactive primary C-H bonds of n-alkanes, with an approximate primary/secondary selectivity of 11:1.