Titanocene-Catalyzed Hydrosilylation of Imines: Experimental and Computational Investigations of the Catalytically Active Species.
2546 - 2553.
In this paper we communicate mechanistic investigations of the asymmetric catalytic hydrosilylation of imines using (R,R)-ethylene-1,2-bis(eta(5)-4,5,6,7-tetrahydro-1-indenyl)titanium (R)-1,1'-binaphth-2-olate (1) and (S,S)-ethylene-1,2-bis(eta(5)-4,5,6,7-tetrahydro-1-indenyl)titanium dichloride (2) as catalyst precursors. After activation with RLi (R = alkyl, aryl) and a silane, these complexes are well-known catalysts for hydrosilylation reactions. However, the exact nature of the catalytic active species is still a subject of debate and was therefore investigated by us using experimental (IR, NMR, EPR, GC/MS) and computational methods. Our results indicate an EBTHITiRSiH2Ph compound (EBTHI = ethylene-1,2-bis(eta(5),5,6,7-tetrahydro-1-indenyl), R = alkyl, aryl) as the catalytically active species. This Ti(IV) species is postulated to be responsible for the lower activities of I and 2 in contrast to hydrosilylations with ethylene-1,2-bis(eta(5)-4,5,6,7-tetrahydro-1-indenyl)titanium difluoride (3), for which a Ti(III)-H compound was postulated to be the active species.
|Title:||Titanocene-Catalyzed Hydrosilylation of Imines: Experimental and Computational Investigations of the Catalytically Active Species|
|Keywords:||EFFECTIVE CORE POTENTIALS, X-RAY-STRUCTURE, ASYMMETRIC HYDROSILYLATION, MOLECULAR CALCULATIONS, KINETIC RESOLUTION, COMPLEXES, TITANIUM, HYDRIDE, HYDROGENATION, POLYMERIZATION|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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