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J Phys Chem A. 2012 Jan 12;116(1):670-9. doi: 10.1021/jp209308a. Epub 2011 Oct 21.

Enantioselectivity in organocatalytic cascade double Michael addition reaction: a theoretical study.

Author information

1
College of Chemistry, Chemical Engineering, and Materials Science, Department of Chemistry, Wenhua East Road 88, Shandong Normal University, Jinan 250014, PR China.

Abstract

We have investigated important intermediates and key transition states of the organocatalyzed cascade double Michael addition using density functional theory. The calculated results suggest that the reaction contains intermolecular nucleophilic addition and intramolecular cyclization, both involving the formation of two stereocenters. The iminium-enamine catalysis of secondary amine unit enables the cascade addition to proceed consecutively. As an electron transport, the iminium attracts the electron stream to promote the nucleophilic addition. Then enamine causes the electron stream to catalyze the cyclization. As H bond donor, the catalyst forms three types of C-H···O H bond with substrates. The enantioselectivity and diastereoselectivity are dominated by the catalyst backbone. Two group links of pyrrole-phenyl and pyrrole-silyl ether orient the reaction in paths with smaller rotations of the linked single bonds. Our conclusion is supported by NBO analysis and the predicted ee, dr values according to the experiment.

PMID:
21985603
DOI:
10.1021/jp209308a
[Indexed for MEDLINE]

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