A study on chiral organocalcium complexes: Attempts in enantioselective catalytic hydrosilylation and intramolecular hydroamination of alkenes
Buch F, Harder S (2008)
Publication Type: Journal article, Original article
Publication year: 2008
Journal
Original Authors: Buch F., Harder S.
Publisher: Verlag der Zeitschrift Fuer Naturforschung
Book Volume: 63
Pages Range: 169-177
Journal Issue: 2
URI: https://www.scopus.com/record/display.uri?eid=2-s2.0-39449126278&origin=inward
Abstract
The chiral β-diketimine ligand [(A)-Ph(Me)CH-N=C(Me)]CHwas prepared by condensation of acetylacetone with the commercially available chiral building block (S)-Ph(Me)CH-NH. Reaction of bis(o-Me N-α-MeSi-benzyl)calcium with this β-diketimine led to double deprotonation. Reaction of bis(o-Me N-α-Me Si-benzyl)calcium with the commercially available chiral bis-oxazoline (S)-Ph-BOX gave diastereopure [(S)-Ph-BOX](o-MeN-α-MeSi-benzyl)calcium which in solution slowly decomposed with formation of o-MeN-α-Me Si-toluene. The corresponding amide complex [(S)-Ph-BOX] CaN(SiMe)(THF) is stable and the crystal structure has been determined. In solution, this heteroleptic amide is in Schlenk equilibrium with the homoleptic species [(S)-Ph-BOX]Ca and Ca[N(SiMe)]-(THF). This Schlenk equilibrium can be steered to the heteroleptic side. Use of the enantiopure calcium amide catalyst for the hydrosilylation of styrene with PhSiH or in the intramolecular hydroamination of aminoalkenes gave good product yields, but only small ee-values were observed (5 -10 %). From stoichiometric reactions of the catalyst with the substrates it is concluded that the "true" catalytically active species is mainly present as a homoleptic calcium complex, which explains the poor enantioselectivities. © 2008 Verlag der Zeitschrift für Naturforschung.
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APA:
Buch, F., & Harder, S. (2008). A study on chiral organocalcium complexes: Attempts in enantioselective catalytic hydrosilylation and intramolecular hydroamination of alkenes. Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 63(2), 169-177.
MLA:
Buch, Frank, and Sjoerd Harder. "A study on chiral organocalcium complexes: Attempts in enantioselective catalytic hydrosilylation and intramolecular hydroamination of alkenes." Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences 63.2 (2008): 169-177.
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