Document Detail

Superacid-catalyzed intramolecular cyclization reaction of arylcyanopropionate: geminal substitution effect on superelectrophilicity.
MedLine Citation:
PMID:  18476746     Owner:  NLM     Status:  MEDLINE    
We present superacid-catalyzed intramolecular cyclization reactions of arylcyanopropionates to give cyclized five- and six-membered beta-enamino esters in moderate to high yields. Known intramolecular ring-closing reactions of protonated nitrile to aromatic carbon atom are limited to the 6-membered case. Interestingly, a significant synergistic increase of reactivity of the cyano functionality was observed, and the cyano nitrogen atom was converted into an amino group, when an ester group was present in a geminal arrangement. Deuterium exchange experiments excluded the involvement of deprotonation of the alpha-proton in the cyclization process. The acidity dependence of the cyclization reactions and (13)C NMR studies of a model compound, methyl cyanoacetate, in various acidic media were consistent with the involvement of the O, N-diprotonated dication of methyl cyanoacetate, a distonic dication, in strong acid, and this is considered to be the de facto electrophile in the present cyclization reaction of arylcyanopropionates.
Satoshi Nakamura; Hiromichi Sugimoto; Tomohiko Ohwada
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-05-14
Journal Detail:
Title:  The Journal of organic chemistry     Volume:  73     ISSN:  0022-3263     ISO Abbreviation:  J. Org. Chem.     Publication Date:  2008 Jun 
Date Detail:
Created Date:  2008-05-30     Completed Date:  2008-08-21     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985193R     Medline TA:  J Org Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4219-24     Citation Subset:  IM    
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
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MeSH Terms
Acids / chemistry*
Magnetic Resonance Spectroscopy
Propionates / chemistry*
Spectrometry, Mass, Electrospray Ionization
Reg. No./Substance:
0/Acids; 0/Propionates

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