N-Vinyl-2-(trifluoroacetylethynyl)pyrroles and E-2-(1-bromo-2- trifluoroacetylethenyl)pyrroles: Cross-coupling vs. addition during CH-functionalization of pyrroles with bromotrifluoroacetylacetylene in solid Al2O3 medium. H-bonding controlстатья
Информация о цитировании статьи получена из
Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 14 августа 2017 г.
Аннотация:A topochemical reaction of pyrroles with bromotrifluoroacetylacetylene proceeds in solid Al2O3 at room
temperature in two different directions depending on the substituent character at the nitrogen atom.
While N-vinylpyrroles undergo the cross-coupling to give N-vinyl-2-(trifluoroacetylethynyl)pyrroles in
up to 58% yield, unsubstituted NH-pyrroles add to the triple bond to afford exclusively E-2-(1-bromo-2-
trifluoroacetylethenyl)pyrroles in 12–21% yields. It has been shown (1H NMR, quantum-chemical
calculations) that the reaction is controlled by the strong intramolecular hydrogen bonding between NH
and carbonyl groups.