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Dr. Jin‐Bao Peng Prof. Dr. Xiao‐Feng Wu 《Angewandte Chemie (International ed. in English)》2018,57(5):1152-1160
The development of highly selective procedures is one of the core goals in organic chemistry. Among the known organic transformations, carbonylation reactions present an ideal choice for the preparation of carbonyl‐containing compounds. In this review, the recent achievements on the control of the selectivity for carbonylation reactions have been summarized. The effects of ligands, solvents, and bases on the selectivity are been discussed. 相似文献
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Yuelan Zhang Dr. Liping Li Qi Li Jianming Fan Jing Zheng Dr. Guangshe Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14196-14204
Developing new methods to synthesize intermetallics is one of the most critical issues for the discovery and application of multifunctional metal materials; however, the synthesis of Sn‐containing intermetallics is challenging. In this work, we demonstrated for the first time that a self‐disproportionation‐induced in situ process produces cavernous Sn?Cu intermetallics (Cu3Sn and Cu6Sn5). The successful synthesis is realized by introducing inorganic metal salts (SnCl2 ? 2 H2O) to NaOH aqueous solution to form an intermediate product of reductant (Na2SnO2) and by employing steam pressures that enhance the reduction ability. Distinct from the traditional in situ reduction, the current reduction process avoided the uncontrolled phase composition and excessive use of organic regents. An insight into the mechanism was revealed for the Sn?Cu case. Moreover, this method could be extended to other Sn‐containing materials (Sn?Co, Sn?Ni). All these intermetallics were attempted in the catalytic effect on thermal decompositions of ammonium perchlorate. It is demonstrated that Cu3Sn showed an outstanding catalytic performance. The superior property might be primarily originated from the intrinsic chemical compositions and cavernous morphology as well. We supposed that this smart solution reduction methodology reported here would provide a new recognition for the reduction reaction, and its modified strategy may be applied to the synthesis of other metals, intermetallics as well as some unknown materials. 相似文献
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Yuqiang Li Dong Wu Hong‐Gang Cheng Guoyin Yin 《Angewandte Chemie (International ed. in English)》2020,59(21):7990-8003
The direct difunctionalization of alkenes, a cheap and abundant feedstock, represents one of the most attractive strategies for increasing molecular complexity in synthetic organic chemistry. In contrast with the 1,2‐difunctionalization of alkenes, recent advances showcase alkene 1,n‐difunctionalizations (n≠2) involving metal migration is an emerging and rapidly growing area of research. This promising strategy not only opens a novel avenue for future development of alkene transformations, but also significantly expands upon the bond disconnections available in modern organic synthesis. This Minireview summarizes recent progress in the migratory difunctionalization of alkenes, with an emphasis on the driving force for metal migration. 相似文献
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Transition metal catalyzed denitrogenative transannulation of a triazole ring has recently received considerable attention as a new concept for the construction of diverse nitrogen-containing heterocyclic cores. This method allows a single-step synthesis of complex nitrogen heterocycles from easily available and cheap triazole precursors. In this Minireview, recent progress of the transition metal catalyzed denitrogenative transannulation of a triazole ring, which was discovered in 2007, is discussed. 相似文献
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Transition‐Metal‐Catalyzed Cyanation by Using an Electrophilic Cyanating Agent,N‐Cyano‐N‐phenyl‐p‐toluenesulfonamide (NCTS) 下载免费PDF全文
The ability to introduce a nitrile group into a biologically active compound is very useful in organic synthesis, owing to the importance of nitrile groups in transformations and tuning molecular properties. To date, nucleophilic cyanation has been the most used strategy for this purpose, whilst electrophilic cyanation reactions are less developed. Recently, the electrophilic cyanation reagent N‐cyano‐N‐phenyl‐p‐toluenesulfonamide (NCTS) has received increasing attention, owing to its superior properties in terms of safety and practicality. This Focus Review summarizes recent progress in transition‐metal‐catalyzed cyanation reactions that use NCTS. 相似文献
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Alessandro Bismuto Patrick Finkelstein Patrick Müller Bill Morandi 《Helvetica chimica acta》2021,104(12):e2100177
In the last twenty years, nickel has successfully imprinted its role in the field of homogeneous catalysis as a valid and complementary alternative to palladium and platinum catalysts. However, compared to those, there are often many different available pathways in nickel catalysis due to the facile access of intermediate oxidation states. Among them, Ni(I) has been increasingly proposed as a key oxidation state in multiple transformations. This oxidation state had already been suggested a long time ago but has only recently undergone a renaissance with extensive ligand design which has led to over 100 isolated Ni(I) complexes. In addition, the analysis of many catalytic cycles has revealed that the Ni(I) species can not only occur as a decomposition product perturbing a Ni(0)–Ni(II) pathway but can also play a key role in alternative Ni(I)–Ni(III) cycles. This behavior is highly dependent on the class of transformation and ligand employed in catalysis. Herein, we concisely describe the journey of this oxidation state, combining the information gathered from inorganic synthesis and mechanistic investigations, from its synthesis to its postulated role in different catalytic cycles. 相似文献
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Hong Zhang Dr. Ran Lin Guangning Hong Tongdao Wang Ting Bin Wen Prof. Dr. Haiping Xia Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):6999-7007
The reactions of phosphonium‐substituted metallabenzenes and metallapyridinium with bis(diphenylphosphino)methane (DPPM) were investigated. Treatment of [Os{CHC(PPh3)CHC(PPh3)CH}Cl2(PPh3)2]Cl with DPPM produced osmabenzenes [Os{CHC(PPh3)CHC(PPh3)CH}Cl2{(PPh2)CH2(PPh2)}]Cl ( 2 ), [Os{CHC(PPh3)CHC(PPh3)CH}Cl{(PPh2)CH2(PPh2)}2]Cl2 ( 3 ), and cyclic osmium η2‐allene complex [Os{CH?C(PPh3)CH?(η2‐C?CH)}Cl2{(PPh2)CH2(PPh2)}2]Cl ( 4 ). When the analogue complex of osmabenzene 1 , ruthenabenzene [Ru{CHC(PPh3)CHC(PPh3)CH}Cl2(PPh3)2]Cl, was used, the reaction produced ruthenacyclohexadiene [Ru{CH?C(PPh3)CH?C(PPh3)CH}Cl{(PPh2)CH2(PPh2)}2]Cl2 ( 6 ), which could be viewed as a Jackson–Meisenheimer complex. Complex 6 is unstable in solution and can easily be convert to the cyclic ruthenium η2‐allene complexes [Ru{CH?C(PPh3)CH?(η2‐C?CH)}Cl{(PPh2)CH2(PPh2)}2]Cl2 ( 7 ) and [Ru{CH?C(PPh3)CH?(η2‐C?CH)}Cl2{(PPh2)CH2(PPh2)}2]Cl ( 8 ). The key intermediates of the reactions have been isolated and fully characterized, further supporting the proposed mechanism for the reactions. Similar reactions also occurred in phosphonium‐substituted metallapyridinium [OsCl2{NHC(CH3)C(Ph)C(PPh3)CH}(PPh3)2]BF4 to give the cyclic osmium η2‐allene‐imine complex [OsCl2{NH?C(CH3)C(Ph)?(η2‐C?CH)}{(PPh2)CH2(PPh2)}(PPh3)]BF4 ( 11 ). 相似文献
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Dr. Yahui Wang Dr. Adam Noble Dr. Eddie L. Myers Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (International ed. in English)》2016,55(13):4270-4274
Enantioenriched secondary and tertiary alkyl pinacolboronic esters undergo enantiospecific deborylative alkynylation through a Zweifel‐type alkenylation followed by a 1,2‐elimination reaction. The process involves use of α‐lithio vinyl bromide or vinyl carbamate species, for which application to Zweifel‐type reactions has not previously been explored. The resulting functionalized 1,1‐disubstituted alkenes undergo facile base‐mediated elimination to generate terminal alkyne products in high yield and excellent levels of enantiospecificity over a wide range of pinacolboronic ester substrates. Furthermore, along with terminal alkynes, internal and silyl‐protected alkynes can be formed by simply introducing a suitable carbon‐ or silicon‐based electrophile after the base‐mediated 1,2‐elimination reaction. 相似文献
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An Easy One‐Pot Synthesis of Diverse 2,5‐Di(2‐pyridyl)pyrroles: A Versatile Entry Point to Metal Complexes of Functionalised,Meridial and Tridentate 2,5‐Di(2‐pyridyl)pyrrolato Ligands 下载免费PDF全文
Alex McSkimming Dr. Mohan M. Bhadbhade Dr. Martin P. Bucknall Hon. Assoc. Prof. Roger W. Read Assoc. Prof. Stephen B. Colbran 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11445-11456
A wide variety of 2,5‐di(2‐pyridyl)pyrroles (dppHs) substituted at the C3 and C4 positions of the pyrrole core were obtained by direct condensation of a 2‐pyridylcarboxaldehyde (2 equiv), an α‐methylene ketone with at least one electron‐withdrawing substituent and ammonium acetate. A novel 2,5‐di(1,10‐phenanthrolin‐2‐yl)pyrrole was also characterised. The dppHs provide a direct, quick entry to dipyridylpyrrolato (dpp?)–metal complexes. The meridial tridentate dpp? ligand is a useful anionic analogue of the terpyridyl ligand. The first (dpp)Ru complexes are described; the 3,4‐substitution of the central pyrrole significantly perturbs the potentials of the redox processes of these complexes. A [(dpp)Ru(bpy)(MeCN)]+ (bpy=2,2′‐bipyridine) complex is an electrocatalyst for the reductive disproportionation of carbon dioxide to carbon monoxide and the carbonate ion. 相似文献
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Azaphilic versus Carbophilic Coupling at CN Bonds: Key Steps in Titanium‐Assisted Multicomponent Reactions 下载免费PDF全文
Torsten Roth Prof. Hubert Wadepohl Dr. Eric Clot Prof. Lutz H. Gade 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18730-18738
Consecutive C‐ and N‐arylation of N‐heterocyclic nitriles is mediated by titanium(IV) alkoxides. The carbo‐ and azaphilic arylation step may be separated by choosing the order in which the two equivalents of aryl transfer reagent are added. In the course of this transformation, the ancillary N‐heterocycle acts as both a directing anchor group and electron reservoir. In the selectivity‐determining step, the selectivity is governed by a choice between (direct) C‐ and Ti‐arylation; the latter opens up a reaction pathway that allows further migration to the nitrogen atom. The isolation of metal‐containing aggregates from the reaction mixture and computational studies gave insights into the reaction mechanism. Subsequently, a multicomponent one‐pot protocol was devised to rapidly access complex quaternary carbon centers. 相似文献