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
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.
Synthesis and biological evaluation of some 4-(isoxazolinyl or 1,2,4-oxadiazolyl) coumarins
作者:Demetrios N. Nicolaides、Konstantina C. Fylaktakidou、Konstantinos E. Litinas、Dimitra Hadjipavlou-Litina
DOI:10.1002/jhet.5570330367
日期:1996.5
the nitrile oxides 4a,b result in compounds 9a,b. The compound 10, prepared from 1 and O-methylhydroxylamine, reacts with nitrile oxide 4b to give the oxadiazole derivative 12. The above referred coumarins are screened for antiinflammatory activity in vivo using the carrageenin rat paw edema and in vitro through their antiproteolytic activity and their ability to inhibit β-glucuronidase and 12-Lipoxygenase