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Formation of a trans ‐cycloadduct from the reaction of difluorocarbene with cis‐difluorostilbene
Author(s) -
GuoZhen Ji,
GuoFei Chen,
ZongMei Wu,
XiKui Jiang
Publication year - 1987
Publication title -
acta chimica sinica english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 0256-7660
DOI - 10.1002/cjoc.19870050313
Subject(s) - difluorocarbene , chemistry , medicinal chemistry
The photochemical isomerization of trans and cis ‐difluorostilbenes has been studied. In the presence of a photosensitizer (biacetyl, 0.05 mol· −1 ) about 75% of the trans form can be converted into the crystalline cis form. The reactions of difluorocarbene (CF 2 ) from the Seyferth reagent (PhHgCF 3 ) with cis ‐ and trans ‐stilbene obey the Skell rule, i. e. , stereospecific cycloaddition. However, although the reaction of CF 2 with trans ‐1,2‐difluorostilbene yields trans ‐1,2‐diphenyl‐perfluorocyclopropane (9) as the only isolable product, the reaction of CF 2 with cis ‐difluorostilbene also gives the same trans ‐cycloadduct as the only isolable product. A possible mechanistic path involving the homolytic cleavage of the highly activated cyclopropane C—C bond facing the CF 2 group is discussed.