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An N‐Heterocyclic‐Carbene–Tetracyanoethylene Zwitterion: Experimental and Theoretical Study on Its Formation and Reactivity
Author(s) -
Song Hayoung,
Kim Youngsuk,
Park Junbeom,
Ko Young Ho,
Kim Kimoon,
Lee Eunsung
Publication year - 2017
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.201601648
Subject(s) - tetracyanoethylene , chemistry , zwitterion , carbene , reactivity (psychology) , cycloaddition , adduct , nitrene , nitrile , photochemistry , medicinal chemistry , isomerization , cyclopentene , molecule , organic chemistry , catalysis , medicine , alternative medicine , pathology
The direct addition of tetracyanoethylene (TCNE) to the carbene center of 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr) was successfully demonstrated. The IPr–TCNE adduct, that is, zwitterion 1 , clearly differs from the typical [2+1]‐cycloaddition products obtained from the reaction of carbenes with olefins. The results obtained from experimental and theoretical studies suggest that adduct 1 disassembles into IPr and TCNE, which is followed by the addition of IPr to the nitrile carbon atom of TCNE and subsequent isomerization into a thermodynamically more stable singlet nitrene intermediate. This intermediate is then captured by an additional molecule of TCNE to afford another heterocycle. This study reveals a unique example of the reactivity between N‐heterocyclic carbenes and olefins.