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1.
Rhodium‐Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight‐Membered Heterocycles
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Dr. Chunxiang Wang Dr. Dongping Wang Hao Yan Dr. Haolong Wang Dr. Bin Pan Dr. Xiaoyi Xin Dr. Xincheng Li Fan Wu Prof. Dr. Boshun Wan 《Angewandte Chemie (International ed. in English)》2014,53(44):11940-11943
N‐aryl‐substituted nitrones were employed as five‐atom coupling partners in the rhodium‐catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C? H activation of the N‐aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight‐membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles. 相似文献
2.
Dr. Elżbieta Gońka Long Yang Ralf Steinbock Dr. Fabio Pesciaioli Dr. Rositha Kuniyil Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16246-16250
The widespread applications of substituted diketopyrrolopyrroles (DPPs) call for the development of efficient methods for their modular assembly. Herein, we present a π-expansion strategy for polyaromatic hydrocarbons (PAHs) by C−H activation in a sustainable fashion. Thus, twofold C−H/N-H activations were accomplished by versatile ruthenium(II)carboxylate catalysis, providing step-economical access to diversely decorated fluorogenic DPPs that was merged with late-stage palladium-catalyzed C−H arylation on the thus-assembled DPP motif. 相似文献
3.
Wei‐Jun Kong Zhigao Shen Lars H. Finger Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(14):5551-5556
Nitrogen‐doped polycyclic aromatic hydrocarbons (aza‐PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza‐PAHs was developed via a rhodium‐catalyzed cascade C?H activation and alkyne annulation. A multifunctional O‐methylamidoxime enabled the high chemo‐ and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C?H activation steps. In addition, the metalla‐electrocatalyzed multiple C?H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups. 相似文献
4.
Rhodium(III)‐Catalyzed Tandem [2+2+2] Annulation–Lactamization of Anilides with Two Alkynoates via Cleavage of Two Adjacent C−H or C−H/C−O bonds
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Miho Fukui Dr. Yu Shibata Yuki Hoshino Haruki Sugiyama Kota Teraoka Prof. Dr. Hidehiro Uekusa Prof. Dr. Keiichi Noguchi Prof. Dr. Ken Tanaka 《化学:亚洲杂志》2016,11(16):2260-2264
An electron‐deficient CpE rhodium(III) complex bearing a cyclopentadienyl ligand with two ethyl ester substituents catalyzes the tandem [2+2+2] annulation–lactamization of acetanilides with two alkynoates via cleavage of adjacent two C?H bonds to give densely substituted benzo[cd]indolones. The reactions of meta‐methoxy‐substituted acetanilides with two alkynoates also provided benzo[cd]indolones via cleavage of adjacent C?H/C?O bonds. Furthermore, 3,5‐dimethoxyacetanilides reacted with two alkynoates to give dearomatized spiro compounds. 相似文献
5.
Mizuho Uryu Taito Hiraga Yoshito Koga Yutaro Saito Kei Murakami Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2020,59(16):6551-6554
Polycyclic aromatic hydrocarbons (PAHs) represent an emerging class of π‐conjugated molecules in the area of optoelectronic devices and materials. Unprecedented synthetic routes to various PAHs from simple phenol derivatives by a palladium‐catalyzed annulative dimerization of phenylene triflate through twofold inter‐ and intramolecular C?H activation have been established. The initially formed partially fused PAHs can be smoothly transformed into a variety of fully fused PAHs by the Scholl reaction. Furthermore, the reactions of phenanthrene‐substituted aryl triflates proceeded regioselectively. The findings inspired the development of a rapid and efficient synthesis of polybenzoacene derivatives. This study not only allows transformation of phenyl triflates, but also discloses a new retrosynthetic strategy towards PAHs, especially polybenzoacenes. 相似文献
6.
Rhodium‐Catalyzed CH Annulation of Nitrones with Alkynes: A Regiospecific Route to Unsymmetrical 2,3‐Diaryl‐Substituted Indoles
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Hao Yan Dr. Haolong Wang Dr. Xincheng Li Dr. Xiaoyi Xin Dr. Chunxiang Wang Prof. Dr. Boshun Wan 《Angewandte Chemie (International ed. in English)》2015,54(36):10613-10617
The direct C? H annulation of anilines or related compounds with internal alkynes provides straightforward access to 2,3‐disubstituted indole products. However, this transformation proceeds with poor regioselectivity in the synthesis of unsymmetrically 2,3‐diaryl substituted indoles. Herein, we report the rhodium(III)‐catalyzed C? H annulation of nitrones with symmetrical diaryl alkynes as an alternative method to prepare 2,3‐diaryl‐substituted N‐unprotected indoles with two different aryl groups. One of the aryl substituents is derived from N?C‐aryl ring of the nitrone and the other from the alkyne substrate, thus providing the indole products with exclusive regioselectivity. 相似文献
7.
Dr. Youai Qiu Cong Tian Leonardo Massignan Torben Rogge Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(20):5818-5822
Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C?H activation is restricted to strongly N‐coordinating directing groups. The first example of electrocatalytic C?H activation by weak O‐coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C?H/O?H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C?H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate. 相似文献
8.
Carboxylic Acids as Traceless Directing Groups for the Rhodium(III)‐Catalyzed Decarboxylative CH Arylation of Thiophenes
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Yuanfei Zhang Huaiqing Zhao Min Zhang Prof. Weiping Su 《Angewandte Chemie (International ed. in English)》2015,54(12):3817-3821
A rhodium(III)‐catalyzed carboxylic acid directed decarboxylative C? H/C? H cross‐coupling of carboxylic acids with thiophenes has been developed. With a slight adjustment of the reaction conditions based on the nature of the substrates, aryl carboxylic acids with a variety of substituents could serve as suitable coupling partners, and a broad variety of functional groups were tolerated. This method provides straightforward access to biaryl scaffolds with diverse substitution patterns, many of which have conventionally been synthesized through lengthy synthetic sequences. An illustrative example is the one‐step gram‐scale synthesis of a biologically active 3,5‐substituted 2‐arylthiophene by way of the current method. 相似文献
9.
One‐Pot Synthesis of Highly Substituted Polyheteroaromatic Compounds by Rhodium(III)‐Catalyzed Multiple CH Activation and Annulation
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Jayachandran Jayakumar Dr. Kanniyappan Parthasarathy Yi‐Hsiang Chen Tai‐Hua Lee Prof. Dr. Shih‐Ching Chuang Prof. Dr. Chien‐Hong Cheng 《Angewandte Chemie (International ed. in English)》2014,53(37):9889-9892
A new method for the synthesis of highly substituted naphthyridine‐based polyheteroaromatic compounds in high yields proceeds through rhodium(III)‐catalyzed multiple C? H bond cleavage and C? C and C? N bond formation in a one‐pot process. Such highly substituted polyheteroaromatic compounds have attracted much attention because of their unique π‐conjugation, which make them suitable materials for organic semiconductors and luminescent materials. Furthermore, a possible mechanism, which involves multiple chelation‐assisted ortho C? H activation, alkyne insertion, and reductive elimination, is proposed for this transformation. 相似文献
10.
Yichen Wu Sbastien Bouvet Susana Izquierdo Alexandr Shafir 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2643-2647
Among halogenated aromatics, iodoarenes are unique in their ability to produce the bench‐stable halogen(III) form. Earlier, such iodine(III) centers were shown to enable C?H functionalization ortho to iodine via halogen‐centered rearrangement. The broader implications of this phenomenon are explored by testing the extent of an unusual iodane‐directed para C?H benzylation, as well as by developing an efficient C?H coupling with sulfonyl‐substituted allylic silanes. Through the combination of the one‐shot nature of the coupling event and the iodine retention, multisubstituted arenes can be prepared by sequentially engaging up to three aromatic C?H sites. This type of iodine‐based iterative synthesis will serve as a tool for the formation of value‐added aromatic cores. 相似文献
11.
Hao Chen Mirxan Farizyan Francesca Ghiringhelli Manuel van Gemmeren 《Angewandte Chemie (International ed. in English)》2020,59(29):12213-12220
The regioselective functionalization of heteroarenes is a highly attractive synthetic target due to the prevalence of multiply substituted heteroarenes in nature and bioactive compounds. Some substitution patterns remain challenging: While highly efficient methods for the C2‐selective olefination of 3‐substituted five‐membered heteroarenes have been reported, analogous methods to access the 5‐olefinated products have remained limited by poor regioselectivities and/or the requirement to use an excess of the valuable heteroarene starting material. Herein we report a sterically controlled C?H olefination using heteroarenes as the limiting reagent. The method enables the highly C5‐selective olefination of a wide range of heteroarenes and is shown to be useful in the context of late‐stage functionalization. 相似文献
12.
A mild and efficient C(sp2)?H nitration of 3‐substituted indoles, by using the economical and non‐toxic cobalt nitrate hexahydrate [Co(NO3)2 ? 6 H2O] as a catalyst and tert‐butyl nitrite (TBN) as the nitro source, is reported. This approach provides a unique methodology involving a site‐selective C?N bond formation for preparation of C‐2 substituted nitro indoles. Utilization of the tBoc as the removable directing group enhances the synthetic utility of the method. 相似文献
13.
Zengbing Bai Chuangxu Cai Wangjian Sheng Yuxiang Ren Huan Wang 《Angewandte Chemie (International ed. in English)》2020,59(34):14686-14692
Transition‐metal‐catalyzed C?H activation has shown potential in the functionalization of peptides with expanded structural diversity. Herein, the development of late‐stage peptide macrocyclization methods by palladium‐catalyzed site‐selective C(sp2)?H olefination of tryptophan residues at the C2 and C4 positions is reported. This strategy utilizes the peptide backbone as endogenous directing groups and provides access to peptide macrocycles with unique Trp–alkene crosslinks. 相似文献
14.
Md Raja Sk Arya Bhattacharyya Shuvendu Saha Arpita Brahma Dr. Modhu Sudan Maji 《Angewandte Chemie (International ed. in English)》2023,62(30):e202305258
Annulative π-extension (APEX) reaction has become a powerful tool for the precise synthesis of well-defined polycyclic aromatic hydrocarbons (PAHs) such as nanographene, graphene, and other PAHs possessing unique structure. Herein, an APEX reaction has been realized at the masked bay-region for the efficient and rapid synthesis of valuable PAH, pyrene, bearing substitutions at the most challenging K-region. RhIII-catalyzed ketone-directed C−H activation at the peri-position of a naphthyl-derived ketone, alkyne-insertion, intramolecular nucleophilic attack at the carbonyl-group, dehydration, and aromatization steps occurred in one-pot to effectuate the protocol. Employing this strategy, a two-fold APEX reaction on enantiopure BINOL-derived ketones provided access to axially-chiral bipyrene derivatives. The detailed DFT study to support proposed mechanism, and synthesis of helical PAHs like dipyrenothiophene and dipyrenofuran are other highlights of the present study. 相似文献
15.
Hai‐Xu Wang Yann Richard Qingyun Wan Cong‐Ying Zhou Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2020,59(5):1845-1850
Described herein is an IrIII/porphyrin‐catalyzed intermolecular C(sp3)?H insertion reaction of a quinoid carbene (QC). The reaction was designed by harnessing the hydrogen‐atom transfer (HAT) reactivity of a metal‐QC species with aliphatic substrates followed by a radical rebound process to afford C?H arylation products. This methodology is efficient for the arylation of activated hydrocarbons such as 1,4‐cyclohexadienes (down to 40 min reaction time, up to 99 % yield, up to 1.0 g scale). It features unique regioselectivity, which is mainly governed by steric effects, as the insertion into primary C?H bonds is favored over secondary and/or tertiary C?H bonds in the substituted cyclohexene substrates. Mechanistic studies revealed a radical mechanism for the reaction. 相似文献
16.
Amidines for Versatile Ruthenium(II)‐Catalyzed Oxidative CH Activations with Internal Alkynes and Acrylates
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Jie Li Dr. Michael John Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5403-5408
Cationic ruthenium complexes derived from KPF6 or AgOAc enabled efficient oxidative C?H functionalizations on aryl and heteroaryl amidines. Thus, oxidative annulations of diversely decorated internal alkynes provided expedient access to 1‐aminoisoquinolines, while catalyzed C?H activations with substituted acrylates gave rise to structurally novel 1‐iminoisoindolines. The powerful ruthenium(II) catalysts displayed a remarkably high site‐, regio‐ and, chemoselectivity. Therefore, the catalytic system proved tolerant of a variety of important electrophilic functional groups. Detailed mechanistic studies provided strong support for the cationic ruthenium(II) catalysts to operate by a facile, reversible C?H activation. 相似文献
17.
Density functional theory calculations were implemented to expand the knowledge about graphyne and its interaction with polycyclic aromatic hydrocarbons (PAHs). Due to the porous character of graphyne, the adsorption strength of PAHs onto graphyne surfaces is expected to be lower with respect to graphene (a perfect π‐extended system). However, there are not quantitative evidences for this assumption. This work shows that the adsorption strength of adsorbed PAHs onto γ‐graphyne nanosheets (GY) is weakened in 12 ? 23% with respect to the adsorption onto graphene, with a decrease of 10 ? 20% in the dispersive interactions. The adsorption energies (in eV) of the GY–PAH systems can be straightforward obtained as E ads/eV≈0.033N H + 0.031N C, where N H and N C is the number of H and C atoms in the aromatic molecule, respectively. This equation predicts the binding energy of graphene–graphyne bilayers with a value of ~31 meV/atom. Analysis of the electronic properties shows that PAHs behaves as n‐dopants for GY, introducing electrons in GY and also reducing its bandgap in up to ~0.5 eV. Strong acceptor or donor substituted PAHs decrease the bandgap of γ‐graphyne in up to ~0.8 eV, with changes in its valence or conduction band, depending on the chemical nature of the adsorbate. Finally, these data will serve for future studies related to the bandgap engineering of graphyne surfaces by nonaggressive molecular doping, and for the development of graphyne‐based materials with potential applications in the removal of persistent aromatic pollutants. 相似文献
18.
Rhodium(III)‐Catalyzed [4+1] Annulation of Aromatic and Vinylic Carboxylic Acids with Allenes: An Efficient Method Towards Vinyl‐Substituted Phthalides and 2‐Furanones
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Dr. Parthasarathy Gandeepan Dr. Pachaiyappan Rajamalli Prof. Dr. Chien‐Hong Cheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(25):9198-9203
A highly regio‐ and stereoselective synthesis of 3,3‐disubstituted phthalides from aryl carboxylic acids and allenes using a rhodium(III) catalyst has been demonstrated. The reaction features broad functional group tolerance and provides a simple and straightforward route to the synthesis of various 3‐vinyl‐substituted phthalides. Furthermore, the catalytic reaction can also be applied to the synthesis of biologically active 5‐vinyl‐substituted 2‐furanones from α,β‐unsaturated carboxylic acids and allenes. The reactions proceed through a carboxylate‐assisted ortho‐C?H activation and [4+1] annulation. The preliminary mechanistic studies suggest that a C?H cleavage is the rate‐determining step. 相似文献
19.
Total Synthesis of Tambromycin by Combining Chemocatalytic and Biocatalytic C−H Functionalization
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Dr. Xiao Zhang Emma King‐Smith Prof. Dr. Hans Renata 《Angewandte Chemie (International ed. in English)》2018,57(18):5037-5041
A combination of genomic and metabolomic approaches recently resulted in the identification of a nonribosomal tetrapeptide tambromycin, which possesses promising antiproliferative activity and several unusual structural features, including a densely substituted indole, a methyloxazoline ring, and an unusual pyrrolidine‐containing amino acid called tambroline. In this work, we identify a concise synthetic route to access tambromycin, which relies on the strategic use of biocatalytic and chemocatalytic C?H functionalization methods to prepare two key precursors to the natural product in an efficient and scalable manner. The success of our study highlights the benefits of applying the principles of biocatalytic retrosynthesis as well as C?H functionalization logic to the synthesis of complex molecular scaffolds. 相似文献
20.
Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of NH Imines and Alkynes by CH/NH Activation
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Ruoyu He Prof. Dr. Zhi‐Tang Huang Prof. Dr. Qi‐Yu Zheng Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2014,53(19):4950-4953
Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N? H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C? H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C? H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle. 相似文献