Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals

Growing attention in developing new N-heterocyclic carbene (NHC)-mediated reactions involving homoenolate intermediates has prompted our interest in exploring the mechanistic details of the related reactions. In this work, we carried out a detailed theoretical study for the NHC-catalyzed annulation...

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Main Authors: Sun, Hui, Fang, Xinqiang, Chi, Robin Yonggui, Li, Guohui
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2013
Online Access:https://hdl.handle.net/10356/98675
http://hdl.handle.net/10220/17504
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-986752020-03-07T12:37:07Z Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals Sun, Hui Fang, Xinqiang Chi, Robin Yonggui Li, Guohui School of Physical and Mathematical Sciences Growing attention in developing new N-heterocyclic carbene (NHC)-mediated reactions involving homoenolate intermediates has prompted our interest in exploring the mechanistic details of the related reactions. In this work, we carried out a detailed theoretical study for the NHC-catalyzed annulation reaction of cinnamaldehyde (A) and benzodi(enone) (B) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). By performing density functional theory calculations, we show clearly the detailed reaction mechanism and rationalize the experimental observation. The reaction of A and B falls into two stages: the formation of homoenolate intermediate and the annulation of homoenolate with B. In the homoenolate formation stage, three possible paths are characterized. The pathway involving the DBU-assisted 1,2-proton transfer with a stepwise mechanism is kinetically more favorable, and the DBU-assisted C1 proton departure is the rate-determining step of the total reaction. The annulation of homoenolate with B involves four elementary steps. The conformational difference of homoenolate (cis and trans) leads to two slightly different reaction processes. In the total reaction, the process involving cis-conformation of A is kinetically more feasible. This can be clearly understood through the frontier molecular orbital analysis and the electronic inductive effect. The calculated results are expected to offer valuable information for further design and development of NHC-mediated reactions. 2013-11-08T06:57:50Z 2019-12-06T19:58:20Z 2013-11-08T06:57:50Z 2019-12-06T19:58:20Z 2013 2013 Journal Article Sun, H., Fang, X., Chi, Y. R., & Li, G. (2013). Theoretical Study of N-Heterocyclic Carbenes-Catalyzed Cascade Annulation of Benzodienones and Enals. Chirality, 25(9), 521-528. https://hdl.handle.net/10356/98675 http://hdl.handle.net/10220/17504 10.1002/chir.22157 en Chirality © 2013 Wiley Periodicals, Inc
institution Nanyang Technological University
building NTU Library
country Singapore
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language English
description Growing attention in developing new N-heterocyclic carbene (NHC)-mediated reactions involving homoenolate intermediates has prompted our interest in exploring the mechanistic details of the related reactions. In this work, we carried out a detailed theoretical study for the NHC-catalyzed annulation reaction of cinnamaldehyde (A) and benzodi(enone) (B) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). By performing density functional theory calculations, we show clearly the detailed reaction mechanism and rationalize the experimental observation. The reaction of A and B falls into two stages: the formation of homoenolate intermediate and the annulation of homoenolate with B. In the homoenolate formation stage, three possible paths are characterized. The pathway involving the DBU-assisted 1,2-proton transfer with a stepwise mechanism is kinetically more favorable, and the DBU-assisted C1 proton departure is the rate-determining step of the total reaction. The annulation of homoenolate with B involves four elementary steps. The conformational difference of homoenolate (cis and trans) leads to two slightly different reaction processes. In the total reaction, the process involving cis-conformation of A is kinetically more feasible. This can be clearly understood through the frontier molecular orbital analysis and the electronic inductive effect. The calculated results are expected to offer valuable information for further design and development of NHC-mediated reactions.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Sun, Hui
Fang, Xinqiang
Chi, Robin Yonggui
Li, Guohui
format Article
author Sun, Hui
Fang, Xinqiang
Chi, Robin Yonggui
Li, Guohui
spellingShingle Sun, Hui
Fang, Xinqiang
Chi, Robin Yonggui
Li, Guohui
Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
author_sort Sun, Hui
title Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
title_short Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
title_full Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
title_fullStr Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
title_full_unstemmed Theoretical study of N-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
title_sort theoretical study of n-heterocyclic carbenes-catalyzed cascade annulation of benzodienones and enals
publishDate 2013
url https://hdl.handle.net/10356/98675
http://hdl.handle.net/10220/17504
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