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1.
Gold‐Catalyzed Formal C−C Bond Insertion Reaction of 2‐Aryl‐2‐diazoesters with 1,3‐Diketones
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《化学:亚洲杂志》2018,13(18):2606-2610
The transition‐metal‐catalyzed formal C−C bond insertion reaction of diazo compounds with monocarbonyl compounds is well established, but the related reaction of 1,3‐diketones instead gives C−H bond insertion products. Herein, we report a protocol for a gold‐catalyzed formal C−C bond insertion reaction of 2‐aryl‐2‐diazoesters with 1,3‐diketones, which provides efficient access to polycarbonyl compounds with an all‐carbon quaternary center. The aryl ester moiety plays a crucial role in the unusual chemoselectivity, and the addition of a Brønsted acid to the reaction mixture improves the yield of the C−C bond insertion product. A reaction mechanism involving cyclopropanation of a gold carbenoid with an enolate and ring‐opening of the resulting donor–acceptor‐type cyclopropane intermediate is proposed. This mechanism differs from that of the traditional Lewis‐acid‐catalyzed C−C bond insertion reaction of diazo compounds with monocarbonyl compounds, which involves a rearrangement of a zwitterion intermediate as a key step. 相似文献
2.
《化学:亚洲杂志》2017,12(15):1865-1868
A facile synthesis of 2‐amino‐1,3‐oxazoles via CuI‐catalyzed oxidative cyclization of enamines and N ,N ‐dialkyl formamides has been developed. The reaction proceeds through an oxidative C−N bond formation, followed by an intramolecular C(sp2)−H bond functionalization/C−O cyclization in one pot. This protocol provides direct access to useful 2‐amino‐1,3‐oxazoles and features protecting‐group‐free nitrogen sources, readily available starting materials, a broad substrate scope and mild reaction conditions. 相似文献
3.
Herein, we present a strategy for the formation of 2‐fluoro‐1,3‐diene derivatives via rhodium‐catalyzed direct C(sp2)—C(sp2) cross‐coupling of gem‐difluoroalkenes and acrylamides. By merging Rh(III)‐catalyzed C(sp2)–H bond activation and nucleophilic addition/F‐elimination of gem‐difluoroalkene, an efficient defluorinative vinylation reaction is uncovered, which leads to the generation of 2‐fluoro‐1,3‐dienes in moderate to good yields with excellent stereoselectivity under mild conditions. Preliminary mechanistic study suggests unique effects of fluorine substituents which allow the reactivity profile not observed with the congeners bearing heavier halides. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(6):1704-1707
A method for cobalt‐catalyzed, carboxylate‐directed functionalization of arene C−H bonds is reported. Alkynes, styrenes, and 1,3‐dienes can be coupled with benzoic acids to provide cyclic products in good yields. The reactions proceed in the presence of a cobalt(II) hexafluoroacetylacetonate catalyst, (TMS)2NH base, Ce(SO4)2 cooxidant, and oxygen oxidant. 相似文献
5.
Adam Neuba Enver Akin Sonja Herres‐Pawlis Ulrich Flrke Gerald Henkel 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(5):m194-m197
The title compounds, namely 2,6‐bis[(1,3‐dimethylimidazolin‐2‐ylidene)amino]pyridinium perchlorate, C15H24N7+·ClO4−, (I), and bis{2,6‐bis[(1,3‐dimethylimidazolin‐2‐ylidene)amino]pyridinium} μ‐oxido‐bis[trichloridoiron(III)], (C15H24N7)2[Fe2Cl6O], (II), are structurally unusual examples of the organization of molecular units via base pairing. The cations in salts (I) and (II) are derived from the bisguanidine N2,N6‐bis(1,3‐dimethylimidazolin‐2‐ylidene)pyridine‐2,6‐diamine, which associates in centrosymmetric pairs via two N—H...N hydrogen‐bond interactions. N—H...N bridges are formed between the protonated pyridine N atom and one of the nonprotonated guanidine N atoms, with N...H distances of 2.01 (1)–2.10 (1) Å. Compound (I) contains two crystallographically independent cations and anions per asymmetric unit. One of the perchlorate anions is disordered, while the [Fe2Cl6O]2− anion lies on an inversion centre. 相似文献
6.
Li‐Jun Xiao Lei Cheng Wei‐Min Feng Mao‐Lin Li Prof. Jian‐Hua Xie Prof. Qi‐Lin Zhou 《Angewandte Chemie (International ed. in English)》2018,57(2):461-464
A Ni‐catalyzed hydroarylation of styrenes and 1,3‐dienes with organoboron compounds has been developed. The reaction offers a highly selective approach to diarylalkanes and allylarenes under redox‐neutral conditions. In this hydroarylation reaction, a new strategy that uses the proton of methanol to generate the active catalyst species Ni?H was developed. The Ni‐catalyzed hydroarylation, combined with a Ir‐catalyzed C?H borylation, affords a very efficient and straightforward access to a retinoic acid receptor agonist. 相似文献
7.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14666-14670
We report a powerful strategy for activation of C−H bonds to produce polysulfonamides by an atom‐economical and green method using iridium‐catalyzed direct C−H amidation polymerization (DCAP). After screening various directing groups, additives, silver salts, concentrations, and temperatures to optimize DCAP, high‐molecular‐weight (up to 149 kDa) and defect‐free polysulfonamides were synthesized from various bis‐sulfonyl azides. Although these polymers do not have conventional fluorescent conjugated cores, they emit blue light with large Stokes shifts and high quantum yields upon photoexcitation owing to an excited‐state intramolecular proton‐transfer process. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11660-11663
Herein, we report a zirconium‐catalyzed enantio‐ and diastereoselective inter/intramolecular double carboalumination of unactivated 2‐substituted 1,5‐dienes, which provides efficient and direct access to chiral cyclopentanes through the generation of two stereocenters, including one all‐carbon quaternary stereocenter, generally with excellent diastereo‐ and high enantioselectivity. This tandem carboalumination process creates two new C−C bonds as well as one C−Al bond, which can be oxidized in situ with O2 or hydrolyzed. Furthermore, the obtained chiral cyclopentanes can be readily functionalized to provide various chiral compounds. 相似文献
9.
《Angewandte Chemie (International ed. in English)》2017,56(20):5536-5540
Heteroatom‐containing organic molecules are of particular interest to medicinal chemists and materials scientists. A strategy to reach these architectures via direct difunctionalization of abundant 1,3‐dienes is especially attractive. Herein, we describe the development of a regio‐ and diastereoselective 1,4‐aminothiolation of 1,3‐dienes with a sulfur diimide reagent, a copper catalyst, and alkyl Grignard reagents. This unique protocol provides remote nitrogen and sulfur functionalities with high levels of stereocontrol. The reaction proceeds via a tandem hetero‐Diels–Alder cycloaddition of N,N′‐bis(benzenesulfonyl)sulfur diimide with 1,3‐diene followed by copper‐catalyzed Grignard substitution. Mechanistic studies support a copper catalyzed formation of an unprecedented [10‐S‐4] sulfurane that reductively eliminates to afford a 3,6‐dihydrothiazine, which is selectively converted to 1,4‐aminothiols. 相似文献
10.
《中国化学》2018,36(8):708-711
We report a palladium‐catalyzed formal intermolecular [4+2] cycloaddition of benzoic and acrylic acids with 1,3‐dienes including the stock chemicals 1,3‐butadiene and isoprene leading to synthetically useful 3,4‐dihydroisocoumarins and 5,6‐dihydrocoumalins. Stepwise C—H bond cleavage and annulation are likely involved in the reaction pathway. The synthetic potential of the methodology was demonstrated by two short derivatizations and total synthesis of natural product Clausamine B. 相似文献
11.
Tobias Pinkert Tristan Wegner Shobhan Mondal Frank Glorius 《Angewandte Chemie (International ed. in English)》2019,58(42):15041-15045
A protocol for the three‐component 1,4‐carboamination of dienes is described. Synthetically versatile Weinreb amides were coupled with 1,3‐dienes and readily available dioxazolones as the nitrogen source using [Cp*RhCl2]2‐catalyzed C?H activation to deliver the 1,4‐carboaminated products. This transformation proceeds under mild reaction conditions and affords the products with high levels of regio‐ and E‐selectivity. Mechanistic investigations suggest an intermediate RhIII–allyl species is trapped by an electrophilic amidation reagent in a redox‐neutral fashion. 相似文献
12.
Dr. Virginie Liautard Damien Jardel Clotilde Davies Muriel Berlande Dr. Thierry Buffeteau Dr. Dominique Cavagnat Dr. Frédéric Robert Dr. Jean‐Marc Vincent Prof. Dr. Yannick Landais 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(43):14532-14539
Enantioselective aldol reactions between substituted pyridine carbaldehydes and α‐ketoacids were shown to provide isotetronic acids or their corresponding pyridinium salts, depending on the nature of the substituents on the pyridine ring. The pyridinium salts were generated through nucleophilic attack of the pyridine nitrogen atom onto the reactive keto functional group. Moderate‐to‐good yields of both compounds were typically obtained and high levels of enantioselectivity were observed by using benzimidazole pyrrolidine I as a catalyst. Hydrogenation of the resulting pyridinium salts led to new indolizidines with high ee values and diastereocontrol. X‐ray diffraction studies allowed the determination of the relative configuration of the products. Finally, DFT calculations were performed to rationalize the divergent pathway as a function of the pyridine substituents. 相似文献
13.
《化学:亚洲杂志》2017,12(19):2524-2527
The direct C−H trifluoromethylation of arenes catalyzed by graphene oxide (GO) under safe conditions is described. This strategy is metal‐free, initiator‐free, safe, and scalable. It employs a readily available CF3 source and the reaction can be easily controlled to obtain a mono‐trifluorinated product. This method opens a new avenue for GO‐catalyzed chemistry. 相似文献
14.
Zhishuo Wang Jiangliang Yin Fulin Zhou Yunqi Liu Jingsong You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):260-264
Reported herein is a rhodium(III)‐catalyzed three‐component annulation reaction of simple pyridines, alkynes, and 1,2‐dichloroethane (DCE), affording a streamlined pathway to diverse ring‐fused pyridiniums. DCE not only serves as a vinyl equivalent but also as an in situ activating agent for pyridine C2?H activation. A cationic five‐membered rhodacycle complex has been isolated and proposed as a possible intermediate. This strategy can be extended to other N‐containing heteroarenes for the synthesis of multiring‐fused pyridiniums. These multicomponent reactions exhibit excellent regioselectivity for 1,3‐diynes, paving a path to the cascade cyclization of 3‐fluoropyridine or N‐methylpyridin‐3‐amine with 1,3‐diynes for the construction of brand‐new tricyclic‐fused pyrano‐ or hydropyridoquinolizinium salts. These ionic fluorophores have been investigated as potential biomarkers. 相似文献
15.
Photosensitizer‐Free Visible‐Light‐Mediated Gold‐Catalyzed 1,2‐Difunctionalization of Alkynes
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Long Huang Dr. Matthias Rudolph Dr. Frank Rominger Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2016,55(15):4808-4813
Under visible‐light irradiation, the gold‐catalyzed intermolecular difunctionalization of alkynes with aryl diazonium salts in methanol affords a variety of α‐aryl ketones in moderate to good yields. In contrast to previous reports on gold‐catalyzed reactions that involve redox cycles, no external oxidants or photosensitizers are required. The reaction proceeds smoothly under mild reaction conditions and shows broad functional‐group tolerance. Further applications of this method demonstrate the general applicability of the arylation of a vinyl gold intermediate instead of the commonly used protodemetalation step. This step provides facile access to functionalized products in one‐pot processes. With a P,N‐bidentate ligand, a stable aryl gold(III) species was obtained, which constitutes the first direct experimental evidence for the commonly postulated direct oxidative addition of an aryl diazonium salt to a pyridine phosphine gold(I) complex. 相似文献
16.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(52):16777-16781
A mild, oxidant‐free, and selective Cp*CoIII‐catalyzed amidation of thioamides with robust dioxazolone amidating agents via C(sp3)−H bond activation to generate the desired amidated products is reported. The method is efficient and allows for the C−H amidation of a wide range of functionalized thioamides with aryl‐, heteroaryl‐, and alkyl‐substituted dioxazolones under the Cp*CoIII‐catalyzed conditions. The observed regioselectivity towards primary C(sp3)−H activation is supported by computational studies and the cyclometalation is proposed to proceed by means of an external carboxylate‐assisted concerted metalation/deprotonation mechanism. The reported method is a rare example of the use of a directing group other than the commonly used pyridine and quinolone classes for Cp*CoIII‐catalyzed C(sp3)−H functionalization and the first to exploit thioamides. 相似文献
17.
《中国化学》2018,36(10):929-933
A new palladium‐catalyzed selective aminomethylation of conjugated 1,3‐dienes with aminals via double C—N bond activation is described. This simple method provides an effective and rapid approach for the synthesis of linear α,β‐unsaturated allylic amines with perfect regioselectivity. Mechanistic studies disclosed that one palladium catalyst cleaved two distinct C—N bond to furnish a cascade double C—N bond activation, in which an allylic 1,3‐diamine and allylic 1,2‐diamine were initially formed as key intermediates through the palladium‐catalyzed C—N bond activation of aminal and the α,β‐unsaturated allylic amine was subsequently produced via palladium‐catalyzed C—N bond activation of the allylic diamines. 相似文献
18.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10675-10680
The silver‐catalyzed oxidative C(sp3)−H/P−H cross‐coupling of 1,3‐dicarbonyl compounds with H‐phosphonates, followed by a chemo‐ and regioselective C(sp3)−C(CO) bond‐cleavage step, provided heavily functionalized β‐ketophosphonates. This novel method based on a readily available reaction system exhibits wide scope, high functional‐group tolerance, and exclusive selectivity. 相似文献
19.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(32):9635-9639
Macromolecules derived from 1,3‐dienes, such as polyisoprene (or natural rubber), are of considerable importance in polymer science. Given the parallels between P=C and C=C bonds, the prospect of polymerizing P‐containing 1,3‐dienes, such as 1‐phosphaisoprene, is intriguing due to the unique chemical functionality imparted by the heavier element combined with their structural relationship to natural rubber. Herein, we report the synthesis, characterization and coordination chemistry of the first polymers derived from Mes*P=CR−CH=CH2 (Mes*=2,4,6‐t‐Bu3C6H2; R=H, Me). In the case of 1‐phosphaisoprene (R=Me), the monomer is isolable and its anionic polymerization affords a polymer that retains P=C bonds in its microstructure. The chemical functionality of these novel materials is demonstrated by forming the macromolecular gold(I) complex where the P=C bond is retained for further chemical elaboration. 相似文献
20.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(6):1517-1521
An iridium/bipyridine‐catalyzed ortho ‐selective C−H borylation of aryl sulfides was developed. High ortho ‐selectivity was achieved by a Lewis acid–base interaction between a boryl group of the ligand and a sulfur atom of the substrate. This is the first example of a catalytic and regioselective C−H transformation controlled by a Lewis acid–base interaction between a ligand and a substrate. The C−H borylation reaction could be conducted on a gram scale, and with a bioactive molecule as a substrate, demonstrating its applicability to late‐stage regioselective C−H borylation. A bioactive molecule was synthesized from an ortho ‐borylated product by converting the boryl and methylthio groups of the product. 相似文献