N E W S
New Publications in Angewandte Chemie
(1) Enantioselective Rhodium-Catalyzed Synthesis of Branched Allylic Amines by Intermolecular Hydroamination of Terminal Allenes
Branching out: The rhodium-catalyzed enantioselective hydroamination of monosubstituted allenes with anilines permits the atom-economic synthesis of valuable branched allylic amines. In contrast to previous linear selective allene hydroaminations, a RhI/Josiphos catalyst system (see scheme; cod=1,5-cyclooctadiene, DCE=1,2-dichloroethane) allows branched allylic amines to be obtained with perfect regioselectivity, high yield, and good enantioselectivity.
M. L. Cooke, Kun Xu, B. Breit, Angew. Chem. 2012, 124, 11034-11037; (link) Angew. Chem. Int. Ed. 2012, 51, 10876-10879. (link)
(2) Mechanistic Insights into a Supramolecular Self-Assembling Catalyst System: Evidence for Hydrogen-Bonding during Rhodium-Catalyzed Hydroformylation
The structural integrity and flexibility provided by intermolecular hydrogen bonds leads to the outstanding properties of the 6-diphenylphosphinopyridin-(2H)-1-one ligand (see scheme) in the rhodium-catalyzed hydroformylation of terminal alkenes, as demonstrated by the combination of spectroscopic methods and DFT computations. Hydrogen bonds were also detected in a competent intermediate of the catalytic cycle.
U. Gellrich, W. Seiche, M. Keller, B. Breit, Angew. Chem. 2012, 124, 11195-11200; (link) Angew. Chem. Int. Ed. 2012, 51, 11033-11038. (link)
(3) Preparation of Alkylmagnesium Reagents from Alkenes through Hydroboration and Boron-Magnesium Exchange
Tolerant: Alkylmagnesium reagents can be synthesized from alkenes through a sequence of hydroboration and subsequent boron–magnesium exchange using a method that tolerates different functional groups (see scheme). The resulting alkylmagnesium reagents can be used in carbon–carbon bond forming reactions, such as alkylation reactions or transition-metal-catalyzed cross-coupling reactions.
M. Reichle, B. Breit, Angew. Chem. 2012, 124, 5828-5832; (link) Angew. Chem. Int. Ed. 2012, 51, 5730-5734. (link) highlighted in SynFacts as Synfact of the Month September (link)
(4) Tandem Rhodium-Catalyzed Hydroformylation-Hydrogenation of Alkenes by Employing a Cooperative Ligand System
Dual action: A multifunctional rhodium catalyst system enables
the simultaneous catalysis of two distinct transformations,
hydroformylation of an alkene and reduction of an aldehyde, in a highly
selective manner. This one-pot/two-step process is controlled by the
cooperative action of two different supramolecular ligand systems and
transforms terminal alkenes into C1-chain-elongated linear
D. Fuchs, G. Rousseau, L. Diab, U. Gellrich, B. Breit, Angew. Chem. 2012, 124, 2220-2224; (link) Angew. Chem. Int. Ed. 2012, 51, 2178-2182. (link)