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1.
Hui Yu Guoying Zhang Hanmin Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(37):11062-11066
A fundamentally novel approach to bioactive quinolizinones is based on the palladium‐catalyzed intramolecular cyclocarbonylation of allylamines. [Pd(Xantphos)I2], which features a very large bite angle, has been found to facilitate the rapid carbonylation of azaarene‐substituted allylamines into bioactive quinolizinones in good to excellent yields. This transformation represents the first dearomative carbonylation and is proposed to proceed by palladium‐catalyzed C N bond activation, dearomatization, CO insertion, and a Heck reaction. 相似文献
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Sasa Duric Fanni D. Sypaseuth Santina Hoof Emma Svensson Prof. Dr. C. Christoph Tzschucke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17456-17463
The synthesis of asymmetrically substituted 2,2′:6′,2′′‐terpyridines is reported. First, palladium‐catalyzed C? H arylation of pyridine N‐oxides with substituted bromopyridines gave 2,2′‐bipyridine N‐oxides, which were further arylated in a second step to form 2,2′:6′,2′′‐terpyridine N‐oxides. Yields of up to 77 % were obtained with N‐oxides bearing an electron‐withdrawing ethoxycarbonyl substituent in the 4‐position. Pd(OAc)2 with either P(tBu)3 or P(o‐tolyl)3 was used as the catalyst. Cyclometalated complexes derived from Pd(OAc)2 and these phosphines were also effective. K3PO4 as the base gave better results than K2CO3. Subsequent deoxygenation with H2 and Pd/C as the catalyst gave the asymmetrically substituted 2,2′:6′,2′′‐terpyridines in near quantitative yield. This reaction sequence significantly reduces the number of steps required in comparison with known cross‐coupling methods and therefore allows convenient and scalable access to substituted terpyridines. 相似文献
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Naohiko Yoshikai Arimasa Matsumoto Jakob Norinder Eiichi Nakamura 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2009,121(16):2969-2972
Naheliegende Alternative : Eine eisenkatalysierte Imin‐gesteuerte C‐H‐Aktivierung mit einem Diarylzinkreagens führt eine Arylgruppe in ortho‐Stellung an einem von Acetophenon abgeleiteten Imin ein (siehe Schema); mit einem Palladiumkatalysator tritt dagegen eine gewöhnliche Substitution auf. Die Titelreaktion ist eine milde C‐H‐Aktivierung, die in Gegenwart von 1,2‐Dichlorisobutan mit Arylbromiden, ‐chloriden oder ‐sulfonaten selektiv verläuft.
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Naohiko Yoshikai Dr. Arimasa Matsumoto Jakob Norinder Dr. Eiichi Nakamura Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(16):2925-2928
No Fe‐ar : Iron catalyzes an imine‐directed C? H bond activation to introduce an ortho‐aryl group to an acetophenone‐derived imine using a diarylzinc reagent (see scheme), whereas palladium catalyzes the conventional substitution reaction . The title reaction features mild and selective C? H bond activation in the presence of aryl bromide, chloride, or sulfonate groups, and 1,2‐dichloroisobutane is essential to achieve such selectivity.
5.
Hai Zhou Yun‐He Xu Wan‐Jun Chung Teck‐Peng Loh Prof. 《Angewandte Chemie (International ed. in English)》2009,48(29):5355-5357
It does get in! A fluoride‐assisted direct cross‐coupling of cyclic enamides with trialkoxy aryl silanes by a palladium‐catalyzed C? H activation leads to a wide range of enamides in yields of up to 95 %.
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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
9.
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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Chris E. Houlden Marc Hutchby Chris D. Bailey J. Gair Ford Dr. Simon N. G. Tyler Dr. Michel R. Gagné Prof. Dr. Guy C. Lloyd‐Jones Prof. Dr. Kevin I. Booker‐Milburn Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1830-1833
Pd and CO—ureally got me! The title reaction proceeds efficiently at 18 °C under CO (1 atm) with 5 % [Pd(OTs)2(MeCN)2] as precatalyst. Depending on the solvents used, either anthranilates or cyclic imides can be obtained in high yields (see picture, BQ=benzoquinone, Ts=4‐toluenesulfonyl).
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Lutz Ackermann Prof. Dr. Rubén Vicente Dr. Anant R. Kapdi Dr. 《Angewandte Chemie (International ed. in English)》2009,48(52):9792-9826
The area of transition‐metal‐catalyzed direct arylation through cleavage of C? H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross‐coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners—including electrophilic aryl chlorides and tosylates as well as simple arenes in cross‐dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations. 相似文献
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Dr. Naohiko Yoshikai Sobi Asako Takeshi Yamakawa Dr. Laurean Ilies Prof. Dr. Eiichi Nakamura 《化学:亚洲杂志》2011,6(11):3059-3065
Direct arylation of the ortho‐C? H bond of an aryl pyridine or an aryl imine with an aryl Grignard reagent has been achieved by using an iron‐diamine catalyst and a dichloroalkane as an oxidant in a short reaction time (e.g., 5 min) under mild conditions (0 °C). The use of an aromatic co‐solvent, such as chlorobenzene and benzene, and slow addition of the Grignard reagent are essential for the high efficiency of the reaction. The present arylation reaction has distinct merits over the previously developed reaction that used an arylzinc reagent, such as its reaction rate and atom economy. Selective C? H bond activation occurs in the presence of a leaving group, such as a tosyloxy, chloro, and bromo group. Studies on a stoichiometric reaction and kinetic isotope effects shed light on the reaction intermediate and the C? H bond‐activation step. 相似文献
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Prof. Dr. Lutz F. Tietze Tim Hungerland Dr. Alexander Düfert Ina Objartel Prof. Dr. Dietmar Stalke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(11):3286-3291
Helical tetrasubstituted alkenes ( 7 ) were obtained in a highly efficient way through a palladium‐catalyzed domino‐carbopalladation/CH‐activation reaction of propargylic alcohols 6 in good to excellent yields. Electron‐withdrawing‐ and electron‐donating substituents can be introduced onto the upper and lower aromatic rings. The substrates ( 6 ) for the domino process were synthesized by addition of the lithiated alkyne ( 20 ) to various aldehydes ( 19 ); moreover, the substrates were accessible enantioselectively (in 95 % ee) by reduction of the corresponding ketone using the Noyori procedure. 相似文献
15.
Wen‐Hao Guo Qiao‐Qiao Min Ji‐Wei Gu Xingang Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(31):9203-9206
An ortho‐selective C F bond borylation between N‐heterocycle‐substituted polyfluoroarenes and Bpin‐Bpin with simple and commercially available [Rh(cod)2]BF4 as a catalyst is now reported. The reaction proceeds under mild reaction conditions with high efficiency and broad substrate scope, even toward monofluoroarene, thus providing a facile access to a wide range of borylated fluoroarenes that are useful for photoelectronic materials. Preliminary mechanistic studies reveal that a RhIII/V catalytic cycle via a key intermediate rhodium(III) hydride complex [(H)RhIIILn(Bpin)] may be involved in the reaction. 相似文献
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Prof. Dr. Hiroaki Ohno Mutsumi Iuchi Dr. Naoto Kojima Prof. Dr. Takehiko Yoshimitsu Prof. Dr. Nobutaka Fujii Prof. Dr. Tetsuaki Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(17):5352-5360
Palladium‐catalyzed cascade C? H alkenylation and arylation provides convenient access to polycyclic aromatic compounds. Treatment of 3‐bromoaniline derivatives bearing a bromocinnamyl group on the nitrogen atom with a catalytic amount of [Pd(OAc)2] and PCy3?HBF4 in the presence of Cs2CO3 in dioxane affords naphthalene‐fused indole derivatives in good yields. This double cyclization reaction is also applicable to heterocyclic substrates, giving fused indoles containing a heteroaromatic ring such as dibenzofuran, dibenzothiophene, carbazole, indole, or benzofuran through heterocyclic C? H arylation. When using a 2,6‐unsubstituted aniline derivative, the first C? H arylation preferentially proceeds at the more hindered position of the aniline ring. 相似文献
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A coordinatively unsaturated iron‐methyl complex having an N‐heterocyclic carbene ligand, [Cp*Fe(LMe)Me] ( 1 ; Cp*=η5‐C5Me5, LMe=1,3,4,5‐tetramethyl‐imidazol‐2‐ylidene), is synthesized from the reaction of [Cp*Fe(TMEDA)Cl] (TMEDA=N,N,N′,N′‐tetramethylethylenediamine) with methyllithium and LMe. Complex 1 is found to activate the C? H bonds of furan, thiophene, and benzene, giving rise to aryl complexes, [Cp*Fe(LMe)(aryl)] (aryl=2‐furyl ( 2 ), 2‐thienyl ( 3 ), phenyl ( 4 )). The C? H bond cleavage reactions are applied to the dehydrogenative coupling of furans or thiophenes with pinacolborane (HBpin) in the presence of tert‐butylethylene and a catalytic amount of 1 (10 mol % to HBpin). The borylation of the furan/thiophene or 2‐substituted furans/thiophenes occurs exclusively at the 2‐ or 5‐positions, respectively, whereas that of 3‐substituted furans/thiophenes takes place mainly at the 5‐position and gives a mixture of regioisomers. Treatment of 2 with 2 equiv of HBpin results in the quantitative formation of 2‐boryl‐furan and the borohydride complex [Cp*Fe(LMe)(H2Bpin)] ( 5 ). Heating a solution of 5 in the presence of tert‐butylethylene led to the formation of an alkyl complex [Cp*Fe(LMe)CH2CH2tBu] ( 6 ), which was found to cleave the C? H bond of furan to produce 2 . On the basis of these results, a possible catalytic cycle is proposed. 相似文献
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Christian Winter Norbert Krause 《Angewandte Chemie (International ed. in English)》2009,48(14):2460-2462
Relieving the strain : The rhodium(I)‐catalyzed activation of C C bonds in functionalized cyclobutanes opens a novel route to highly substituted carbo‐ and heterocycles. Particularly intriguing is the differentiation of enantiotopic C C bonds, which leads to the formation of highly enantiomerically enriched lactones, cyclopentanones, and cyclohexenones (see scheme).
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