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Mechanism and Enantioselectivity of [Zinc(diamine)(diol)]‐Catalyzed Asymmetric Hydrosilylation of Ketones: DFT, NMR and ECD Studies
Author(s) -
Gajewy Jadwiga,
Gawronski Jacek,
Kwit Marcin
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201200992
Subject(s) - chemistry , hydrosilylation , ketone , catalysis , hydride , diol , substrate (aquarium) , diamine , reaction mechanism , reactivity (psychology) , silane , stereochemistry , medicinal chemistry , computational chemistry , organic chemistry , hydrogen , medicine , oceanography , alternative medicine , pathology , geology
NMR and ECD measurements together with density functional theory computations were used to analyze the mechanism of [Zn(diamine)(diol)]‐catalyzed ketone hydrosilylation. Of the three possible pathways, the one that assumes formation of a Zn‐hydride species acting as an active catalyst appears energetically most favorable. This conclusion is in contrast to a previously proposed mechanism that assumed the reaction between the [Zn(diamine)(diol)] catalyst, the silane, and the substrate, took place through Zn‐activation of the carbonyl group. The absolute stereochemistry of the final product predicted on the basis of our proposal is in agreement with the available experimental data. It appears that the most important factor that controls stereochemistry of the whole process is preorganization of the reaction substrates by formation of a NH ··· O=C hydrogen bond between the catalyst and the substrate.