香豆素染料的高级时变密度泛函理论(TD-DFT)计算模型已被用来指导有效光催化剂(PC)的设计。从理论角度研究了香豆素库,并评估了光物理/电化学性质(吸收和发射光谱,E 00,氧化和还原电势)。与报告的一些候选人的文献价值进行比较已用于评估理论水平。根据获得的结果,新的还原性强的PC [ E ox(PC 。+/PC*)=−2.1 – −2.0 V vs SCE]。通过对结构-性质关系的计算研究,已经合成了许多香豆素衍生物,并在甲醛的频哪醇偶联中作为模型反应进行了评估。新型有机光氧化还原催化剂根据计算预测的数据显示了实验光物理和电化学数据,其激发态还原电势超过了高度还原的过渡金属基PC的电势。对它们作为PC的行为进行的仔细研究表明,在一般的光氧化还原催化中需要考虑到一些关键问题,从而阐明了频哪醇以及其他光氧化还原反应中这些PC的使用。
A new regioselective alpha-arylation of coumarins with unactivated simple arenes via a palladium-catalyzed twofold C-H functionalization is devised. This method offers an attractive new approach to synthesis of a wide variety of 3-arylcoumarins from readily accessible starting materials.
Palladium-Catalyzed Decarboxylative Cross-Coupling Reactions: A Route for Regioselective Functionalization of Coumarins
作者:Farnaz Jafarpour、Samaneh Zarei、Mina Barzegar Amiri Olia、Nafiseh Jalalimanesh、Soraya Rahiminejadan
DOI:10.1021/jo302778d
日期:2013.4.5
A straightforward, regioselective, and step-economical ligand-free palladium-catalyzed decarboxylative functionalization of coumarin-3-carboxylic acids is devised. This protocol is compatible with a wide variety of electron-donating and -withdrawing substituents and allows for construction of various biologically important π-electron extended coumarins.
Metal-free C(3)–H arylation of coumarins promoted by catalytic amounts of 5,10,15,20-tetrakis(4-diethylaminophenyl)porphyrin
作者:Masahiro Kojima、Kounosuke Oisaki、Motomu Kanai
DOI:10.1039/c5cc02349a
日期:——
Metal-free, Meerwein-type C(3)–H arylation of coumarins was achieved in the presence of catalytic amounts of 5,10,15,20-tetrakis(4-diethylaminophenyl)porphyrin.