Insights into the role of zirconium in proline functionalized metal-organic frameworks attaining high enantio- and diastereoselectivity
Nguyen KD, Kutzscher C, Ehrling S, Senkovska I, Bon V, De Oliveira M, Gutmann T, Buntkowsky G, Kaskel S (2019)
Publication Type: Journal article
Publication year: 2019
Journal
Book Volume: 377
Pages Range: 41-50
DOI: 10.1016/j.jcat.2019.07.003
Abstract
A chiral zirconium-based catalyst, DUT-67-Pro containing 8-connected Zr6-clusters is obtained by post synthetic functionalization of Zr6O6(OH)2(TDC)4(HCOO)2 (DUT-67, TDC = 2,5-thiophenedicarboxylate) with the chiral monocarboxylic acid, L-proline. 13C and 15N solid state MAS and DNP NMR studies of DUT-67-Pro confirm the integration of L-proline into the porous framework. The chiral MOF catalyst exhibits an excellent catalytic activity at low temperature (298 K) with an unprecedented syn-(S,S)-product selectivity in an asymmetric aldol addition reaction of cyclohexanone to 4-nitrobenzaldehyde (yield = 95%, ee = 96%). Comparative catalytic studies using a molecular Zr6-cluster model compound indicate the Zr6-moiety to be responsible for this inverse diastereoselectivity compared to well-established L-proline organocatalysis and a mechanism is proposed to explain the Zr6-cluster-mediated syn-selectivity. Masking residual acidic active sites in the cluster of the framework was found to be a key prerequisite to achieve the high enantioselectivity. The purely heterogeneous catalytic system based on DUT-67-Pro is highly stable and can be recycled several times.
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How to cite
APA:
Nguyen, K.D., Kutzscher, C., Ehrling, S., Senkovska, I., Bon, V., De Oliveira, M.,... Kaskel, S. (2019). Insights into the role of zirconium in proline functionalized metal-organic frameworks attaining high enantio- and diastereoselectivity. Journal of Catalysis, 377, 41-50. https://doi.org/10.1016/j.jcat.2019.07.003
MLA:
Nguyen, Khoa D., et al. "Insights into the role of zirconium in proline functionalized metal-organic frameworks attaining high enantio- and diastereoselectivity." Journal of Catalysis 377 (2019): 41-50.
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