Palladium catalyzed Heck-arylation/cyclization cascade: An environmentally benign and efficient synthesis of 4-arylcoumarins in water
作者:Junmin Chen、Wei Liu、Liandi Zhou、Yongli Zhao
DOI:10.1016/j.tetlet.2018.05.032
日期:2018.6
An environmentally benign and efficient approach for the synthesis of 4-arylcoumarins from ortho-hydroxy cinnamate ester derivatives with aryl iodides was developed in water under aerobic conditions. This transformation proceeds through a palladiumcatalyzed Heck-arylation/cyclization cascade reaction. The present protocol features a wide substrate scope and readily available starting materials to
coumarin-3-carboxylic acids is developed. This approach enables controlled protodecarboxylation/regioselective C–H arylation of coumain-3-carboxylic acids in one-pot using a monometallic catalytic system. A wide variety of electron-donating and -withdrawing substituents on both coumarins and arylboronic acid are tolerated under the reaction conditions and 4-aryl coumarins are constructed in high yields.
Vinyl Nosylates: An Ideal Partner for Palladium-Catalyzed Cross-Coupling Reactions
作者:Nicolas P. Cheval、Anna Dikova、Aurélien Blanc、Jean-Marc Weibel、Patrick Pale
DOI:10.1002/chem.201300127
日期:2013.7.1
In a hurry to leave! Nosylates act as an excellent leavinggroup in various palladium‐catalyzed cross‐couplings, such as Suzuki, Stille, Heck, and Sonogashira reactions (see scheme). Crystalline, stable, and cheap vinyl and aryl nosylates proved better than classical halides and triflates, consistently giving higher yields of coupling products. Their usefulness in CCbondformation was also demonstrated
Photoinduced cyclization of alkynoates to coumarins with N-Iodosuccinimide as a free-radical initiator under ambient and metal-free conditions
作者:Zhihui Wang、Xuezhi Li、Lei Wang、Pinhua Li
DOI:10.1016/j.tet.2019.01.013
日期:2019.2
a free-radical initiator and under LED (380–385 nm) irradiation and metal-free conditions, the reaction of alkynoates underwent smoothly to afford the corresponding coumarins in high yields at room temperature with broad substrate scope via freeradical intramolecular cyclization and ester rearrangement.
Cascade Synthesis of 4-Arylcoumarins: Pd-Catalyzed Arylations and Cyclizations with (<i>E</i>
)-Ethyl 3-(2-Hydroxyaryl)acrylates and Triarylantimony Difluorides
The reactions of 3‐(2‐hydroxyaryl)acrylates with triarylantimony difluorides in the presence of Pd(OAc)2 and 2,2'‐bipyridyl under aerobic conditions afforded 4‐arylcoumarins in good‐to‐excellent yields with all of the arylgroups in the triarylantimony difluoride transferred to the coupling products. This protocol increases the synthetic scope of 4‐arylcoumarins, especially those bearing electron‐withdrawing