共查询到20条相似文献,搜索用时 0 毫秒
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Wenbo Ma Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13925-13928
Cationic ruthenium(II) complexes enabled oxidative alkenylations of phenols bearing easily cleavable directing groups. The optimized catalytic system allowed twofold C? H bond activations with excellent chemo‐, site‐, and diastereoselectivities. The double C? H functionalization process proceeded efficiently in an aerobic fashion under an atmosphere of ambient air. Detailed mechanistic studies were performed and provided strong support for an initial reversible C? H bond activation by the formation of six‐membered ruthenacycles as the key intermediates. 相似文献
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Masashi Shigenobu Kazuhiro Takenaka Hiroaki Sasai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(33):9708-9712
A palladium‐catalyzed direct arylation of isoxazoles with aryl iodides has been achieved. The C H bond at the 5‐position is activated selectively to give coupling products in moderate to good yields. This direct arylation was applied to the synthesis of a spiro‐type chiral ligand, which proved to be most effective to the palladium‐catalyzed tandem cyclization of a dialkenyl alcohol. 相似文献
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Masashi Shigenobu Kazuhiro Takenaka Hiroaki Sasai 《Angewandte Chemie (International ed. in English)》2015,54(33):9572-9576
A palladium‐catalyzed direct arylation of isoxazoles with aryl iodides has been achieved. The C H bond at the 5‐position is activated selectively to give coupling products in moderate to good yields. This direct arylation was applied to the synthesis of a spiro‐type chiral ligand, which proved to be most effective to the palladium‐catalyzed tandem cyclization of a dialkenyl alcohol. 相似文献
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Nadine Kuhl Dr. Matthew N. Hopkinson Dr. Joanna Wencel‐Delord Prof. Dr. Frank Glorius 《Angewandte Chemie (International ed. in English)》2012,51(41):10236-10254
The use of coordinating moieties as directing groups for the functionalization of aromatic C? H bonds has become an established tool to enhance reactivity and induce regioselectivity. Nevertheless, with regard to the synthetic applicability of C? H activation, there is a growing interest in transformations in which the directing group can be fully abandoned, thus allowing the direct functionalization of simple benzene derivatives. However, this approach requires the disclosure of new strategies to achieve reactivity and to control selectivity. In this review, recent advances in the emerging field of non‐chelate‐assisted C? H activation are discussed, highlighting some of the most intriguing and inspiring examples of induction of reactivity and selectivity. 相似文献
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Hang Zhang Kang Wang Bo Wang Heng Yi Fangdong Hu Changkun Li Yan Zhang Jianbo Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(48):13450-13454
An efficient rhodium(III)‐catalyzed synthesis of 2H‐chromene from N‐phenoxyacetamides and cyclopropenes has been developed. The reaction represents the first example of using cyclopropenes as a three‐carbon unit in rhodium(III)‐catalyzed C(sp2) H activations. 相似文献
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Baihua Ye Nicolai Cramer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(30):8030-8033
Directed Cp*RhIII‐catalyzed carbon–hydrogen (C H) bond functionalizations have evolved as a powerful strategy for the construction of heterocycles. Despite their high value, the development of related asymmetric reactions is largely lagging behind due to a limited availability of robust and tunable chiral cyclopentadienyl ligands. Rhodium complexes comprising a chiral Cp ligand with an atropchiral biaryl backbone enables an asymmetric synthesis of isoindolones from arylhydroxamates and weakly alkyl donor/acceptor diazo derivatives as one‐carbon component under mild conditions. The complex guides the substrates with a high double facial selectivity yielding the chiral isoindolones in good yields and excellent enantioselectivities. 相似文献
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Zi‐Qi Lin Wei‐Zhen Wang Shao‐Bai Yan Wei‐Liang Duan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(21):6363-6367
A palladium‐catalyzed enantioselective C H arylation of N‐(o‐bromoaryl)‐diarylphosphinic amides is described for the synthesis of phosphorus compounds bearing a P‐stereogenic center. The method provides good enantioselectivities and high yields. The products were readily transformed into P‐chiral biphenyl monophosphine ligands. 相似文献
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Yasuaki Kawaguchi Shigeo Yasuda Akira Kaneko Yuki Oura Chisato Mukai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(29):7738-7742
The efficient RhI‐catalyzed cycloisomerization of benzylallene‐alkynes produced the tricyclo[9.4.0.03,8]pentadecapentaene skeleton through a C H bond activation in good yields. A plausible reaction mechanism proceeds via oxidative addition of the acetylenic C H bond to RhI, an ene‐type cyclization to the vinylidenecarbene–RhI intermediate, and an electrophilic aromatic substitution with the vinylidenecarbene species. It was proposed based on deuteration and competition experiments. 相似文献
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Xueyun Zhang Zisong Qi Xingwei Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(40):10970-10974
[Cp*RhIII]‐catalyzed C H activation of arenes assisted by an oxidizing N O or N N directing group has allowed the construction of a number of hetercycles. In contrast, a polar N O bond is well‐known to undergo O‐atom transfer (OAT) to alkynes. Despite the liability of N O bonds in both C H activation and OAT, these two important areas evolved separately. In this report, [Cp*RhIII] catalysts integrate both areas in an efficient redox‐neutral coupling of quinoline N‐oxides with alkynes to afford α‐(8‐quinolyl)acetophenones. In this process the N O bond acts as both a directing group for C H activation and as an O‐atom donor. 相似文献