期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 14, 期 18, 页码 5555-5566出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.200800411
关键词
alcohols; Heck reaction; hydrogen bonds; palladium catalysis; regioselectivity
资金
- EPSRC [EP/F000316/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/F000316/1] Funding Source: researchfish
A general method for the regioselective Heck reaction of electron-rich olefins is presented. Fast, highly regioselective Pd-catalysed alpha-arylation of electron-rich olefins, vinyl ethers (1a-d), hydroxyl, vinyl ethers (1e,f), enamides (1g,h) and a substituted vinyl ether (1i) has been accomplished with a diverse range of aryl bromides (2a-r), for the first time, in cheap, green and easily available alcohols with no need for any halide scavengers or salt additives. The reaction proceeds with high efficiency, leading exclusively to the a-products, in 2-propanol and particularly in ethylene glycol. In the latter, the arylation can be catalysed at a palladium loading of 0.1 mol% and finish in as short a time as 0.5 h. The remarkable performance of the alcohol solvents in promoting a regiocontrol is attributed to their hydrogen-bond-donating capability, which is believed to facilitate the dissociation of halide anions from Pd-II, and hence, the generation of a key ionic Pd-II-olefin intermediate responsible for the alpha product. This belief is further strengthened by the study of a benchmark arylation reaction in 21 different solvents. The study revealed that exclusive alpha-regioselective arylation takes place in almost all of the protic solvents, and there is a rough correlation between the alpha-arylation rates and the solvent parameter E-T(N). The method is simpler, cleaner and more general than those established thus far.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据