83670-63-7Relevant academic research and scientific papers
Organo[2-(hydroxymethyl)phenyl]dimethylsilanes as mild and reproducible agents for rhodium-catalyzed 1,4-addition reactions
Nakao, Yoshiaki,Chen, Jinshui,Imanaka, Hidekazu,Hiyama, Tamejiro,Ichikawa, Yoshitaka,Duan, Wei-Liang,Shintani, Ryo,Hayashi, Tamio
, p. 9137 - 9143 (2008/02/09)
Stable and reusable tetraorganosilicon reagents, alkenyl-, aryl-, and silyl[2-(hydroxymethyl)phenyl]-dimethylsilanes, undergo 1,4-addition reactions to α,β-unsaturated carbonyl acceptors under mild rhodium-catalysis. The reaction tolerates a diverse range of functional groups and is applicable to gram-scale synthesis. Use of a chiral diene ligand allows the achievement of the corresponding enantioselective transformations using the tetraorganosilicon reagents, providing the silicon-based approach to optically active ketones and substituted piperidones that serve as synthetic intermediates of pharmaceuticals. A rhodium alkoxide species is suggested to be responsible for a transmetalation step on the basis of the observed kinetic resolution of a racemic chiral phenylsilane in the enantioselective 1,4-addition reaction under the rhodium-chiral diene catalysis.
Highly enantioselective conjugate additions of potassium organotrifluoroborates to enones by use of monodentate phosphoramidite ligands
Duursma, Ate,Boiteau, Jean-Guy,Lefort, Laurent,Boogers, Jeroen A. F.,De Vries, Andre H. M.,De Vries, Johannes G.,Minnaard, Adriaan J.,Feringa, Ben L.
, p. 8045 - 8052 (2007/10/03)
The use of phosphoramidite ligands in the rhodium-catalyzed asymmetric conjugate addition of potassium organotrifluoroborates to various enones in the absence of water is described. A systematic search for effective catalysts has been performed by use of high-throughput screening methods. Initially, we have screened reaction conditions, catalyst precursors, and focused ligand libraries. In the next stage we have used the monodentate ligand combination approach, and finally we have made a library of 96 different phosphoramidites by parallel synthesis in the robot (instant ligand libraries) and have tested these in the vinylation of cyclohexenone (up to 88% enantiomeric excess, ee) and 4-phenyl-3-buten-2-one (up to 42% ee). Arylation of cyclohexenone by use of potassium phenyltrifluoroborate gave 3-phenylcyclohexanone with 99% ee.
Synthesis and application in asymmetric C-C bond formation of solution phase ligand libraries of monodentate phosphoramidites
Duursma, Ate,Lefort, Laurent,Boogers, Jeroen A.F.,De Vries, Andre H.M.,De Vries, Johannes G.,Minnaard, Adriaan J.,Feringa, Ben L.
, p. 1682 - 1684 (2007/10/03)
The synthesis of solution phase libraries of chiral monodentate phosphoramidite by using the automated parallel protocol was analyzed. It was observed that the method leads to the analysis of effective enantioselective catalysts for tranformations and association with the monodentate ligand combination approach. The automated parallel protocol provided a powerful tool for the combinatorial asymmetric catalysis. The chromatography was performed at the end of the phosphoramidite synthesis by a filtration process, due to more simple automated procedure.
