- One-pot Synthesis of Fused Dipyranocoumarins from Dihydroxycoumarins and Propargyl Chlorides under Microwave Irradiation
-
Dipetalolactone and 4-methyldipetalolactone are prepared in excellent yield by a one-pot tandem propargylation/Claisen rearrangement/cyclization reaction of the corresponding 5,7-dihydroxycoumarins with 3-chloro-3-methylbut-1-yne in the presence of Cs2CO3 under microwave irradiation. The analogous reactions of propargyl chloride with esculetins or 5,7-dihydroxycoumarins led to dipropargyloxy derivatives. The later by treatment with gold nanoparticles supported on TiO2 or BF3.Et2O in N,N-dimethylformamide (DMF) under microwave irradiation resulted in very good to excellent yield to the corresponding fused dipyranocoumarins. The reactions of esculetins with 3-chloro-3-methylbut-1-yne gave mainly exomethylene fused dioxino[g]coumarins.
- Vlachou, Evangelia-Eirini N.,Gabriel, Catherine,Litinas, Konstantinos E.
-
-
Read Online
- Synthesis and evaluation of substituted 8,8-dimethyl-8H-pyrano[2,3-f]chromen-2-one derivatives as vasorelaxing agents
-
A series of substituted 8,8-dimethyl-8H-pyrano[2,3-f]chromen-2-ones (chromeno-coumarin hybrids) was synthesized from scopoletin (11) as vasorelaxing agents. The synthesized compounds 21a-f, 22, 23a-e and scopoletin (11) were evaluated for vasorelaxation in endothelium intact rat main mesenteric artery (MMA). Compounds 11, 21a, 21c-f and 22 showed significant vasorelaxation in precontracted MMA within the range of EC50 value 1.58–5.02 μM. These derivatives presented 29.40–70.89 fold increased sensitivity for experimental tissue compared to scopoletin (11), the parent molecule. Among others, 22 was found to be the most active compound which had EC50 1.58 μM with 70.89 fold increased sensitivity. The mechanistic evaluation of 22 showed that it exerted vasorelaxation through Ca2+-activated K+ (BKca) channel and the effect was endothelium-independent.
- Singh, Sarita,Agarwal, Karishma,Iqbal, Hina,Yadav, Pankaj,Yadav, Deepika,Chanda, Debabrata,Tandon, Sudeep,Khan, Feroz,Gupta, Anil Kumar,Gupta, Atul
-
supporting information
(2019/11/26)
-