Access to 4-Alkenylated Coumarins via Ruthenium-Catalyzed Olefinic C–H Alkenylation of Coumarins with Modifiable and Removable Directing Groups
摘要:
The ruthenium-catalyzed activation of the C4 position of coumarins for coupling with acrylates was described using modifiable ketone as a directing group. The alkenylation reaction provided a direct approach to prepare previously inaccessible 4-alkenylated coumarins with operational simplicity and high atom-economy. This protocol also worked well with coumarin-3-carboxylic acids to unveil a rare instance of a tandem alkenylation/decarboxylation reaction. The potential value of this approach was further highlighted by the efficient synthesis of several heterocyclic fused coumarin derivatives.
1,3-cycloaddition reactions of 2-oxo-2<i>H</i>-[1]benzopyran-4-carbonitrile<i>N</i>-oxide. Synthesis of several new 4-substituted coumarins
作者:Demetrios N. Nicolaides、Konstantina C. Fylaktakidou、Konstantinos E. Litinas、George K. Papageorgiou、Dimitra J. Hadjipavlou-Litina
DOI:10.1002/jhet.5570350321
日期:1998.5
1,3-Cycloadditionreactions of new2-oxo-2H-[1]benzopyran-4-carbonitrile N-oxide 2 with dipolarophiles, o-aminophenols and o-phenylenediamine resulted in 4-heterocyclic substituted coumarin derivatives. These derivatives are screened for antiinflammatory activity in vitro through their antiproteolytic activity, the interaction with 1,1-diphenyl-2-picrylhydrazyl and the ability to affect superoxide