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Palladium‐Catalyzed Stereoselective Intramolecular Oxidative Amidation of Alkenes in the Synthesis of 1,3‐ and 1,4‐Amino Alcohols and 1,3‐Diamines 下载免费PDF全文
Prof. Dr. Andrei V. Malkov Dr. Darren S. Lee Dr. Maciej Barłóg Dr. Mark R. J. Elsegood Prof. Dr. Pavel Kočovský 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):4901-4905
An efficient and practical Pd‐catalyzed intramolecular oxidative allylic amidation provides facile access to derivatives of 1,3‐ and 1,4‐amino alcohols and 1,3‐diamines. The method operates under mild reaction conditions (RT) with molecular oxygen (1 atm) as the sole reoxidant of Pd. Excellent diastereoselectivities were attained with substrates bearing a secondary stereogenic center 相似文献
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A Versatile Synthesis of β‐Lactam‐Fused Oxacycles through the Palladium‐Catalyzed Chemo‐, Regio‐, and Diastereoselective Cyclization of Allenic Diols 下载免费PDF全文
Prof. Dr. Benito Alcaide Dr. Pedro Almendros Dr. Rocío Carrascosa Dr. Luis Casarrubios Dr. Elena Soriano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):2200-2213
Chemo‐, regio‐ and stereocontrolled palladium‐catalyzed preparations of enantiopure morpholines, oxocines, and dioxonines have been developed starting from 2‐azetidinone‐tethered γ,δ‐, δ,ε‐, and ε,ζ‐allendiols. The palladium‐catalyzed cyclizative coupling reaction of γ,δ‐allendiols 2 with allyl bromide or lithium bromide was effective as 8‐endo cyclization by attack of the primary hydroxy group to the terminal allene carbon to afford enantiopure functionalized oxocines; whereas the palladium‐catalyzed cyclizative coupling reaction of 2‐azetidinone‐tethered ε,ζ‐allendiols 4 furnished dioxonines 16 through a totally chemo‐ and regioselective 9‐endo oxycyclization. By contrast, the palladium‐catalyzed cyclizative coupling reaction of 2‐azetidinone‐tethered δ,ε‐allendiols 3 with aryl and alkenyl halides exclusively generated six‐membered‐ring compounds 14 a and 15 a . These results could be explained through a 6‐exo cyclization by chemo‐ and regiospecific attack of the secondary hydroxy group to the internal allene carbon. Chemo‐ and regiocontrol issues are mainly influenced by the length of the tether rather than by the nature of the metal catalysts and substituents. This reactivity can be rationalized by means of density functional theory calculations. 相似文献
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Guillaume Berthon‐Gelloz Dr. Mélanie Marchant Bernd F. Straub Prof. Dr. Istvan E. Marko Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(12):2923-2931
Pd 0 does the trick! Alkenyl silanes are efficiently cyclopropanated by diazoalkanes at low Pd loadings (see scheme). Clear evidence for the involvement of a Pd0 resting state for this reaction is given.
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A Ca2+‐, Mg2+‐, and Zn2+‐Based Dendritic Contractile Nanodevice with Two pH‐Dependent Motional Functions 下载免费PDF全文
Adrian‐Mihail Stadler Lydia Karmazin Corinne Bailly 《Angewandte Chemie (International ed. in English)》2015,54(48):14570-14574
A contractile dendritic motional device is reported where metal ions with biological importance—Ca2+ (the main regulatory and signaling species of the natural muscles), Mg2+, and Zn2+—initiate two kinds of motional functions. The first motional function is the metal‐ion‐induced contraction of a linear strand into a Z‐shaped dinuclear complex, and the second one is the change of the height of Z‐shaped complexes via transmetalation. By means of the pH‐dependent counterligand tren, the two motional features of the machine can depend on alternate additions of acid and base. An optical response is associated with the conversion of the linear form (which is yellow) into the metalated Z‐shaped one (which is red). 相似文献
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Pd0‐Catalyzed Intramolecular α‐Arylation of Sulfones: Domino Reactions in the Synthesis of Functionalized Tetrahydroisoquinolines 下载免费PDF全文
Prof.Dr. Daniel Solé Ferran Pérez‐Janer Dr. Raffaella Mancuso 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4580-4584
A new strategy for the synthesis of tetrahydroisoquinolines based on the Pd0‐catalyzed intramolecular α‐arylation of sulfones is reported. The combination of this Pd‐catalyzed reaction with intermolecular Michael and aza‐Michael reactions allows the development of two‐ and three‐step domino processes to synthesize diversely functionalized scaffolds from readily available starting materials. 相似文献
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Adrien T. Normand Dr. Mikhail S. Nechaev Dr. Kingsley J. Cavell Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(29):7063-7073
A detailed experimental and DFT study (PBE level) of the reaction of [Pd(η3‐C3H5)(tmiy)(PR3)]BF4 (tmiy=tetramethylimidazolin‐2‐ylidene, PR3=phosphane), precursors to monoligated Pd0 species, with aryl electrophiles yielding 2‐arylimidazolium salt is reported. Experiments establish that an autocatalytic ligand transfer mechanism is preferred over PdIV and σ‐bond metathesis pathways, and that transmetalation is the rate‐determining step. Calculations indicate that the key step involves the concerted exchange of NHC and iodo ligands between two different PdII complexes. This is corroborated by experimental results showing the slower reaction of complexes containing the bulkier dipdmiy (dipdmiy = diisopropyldimethylimidazolin‐2‐ylidene). 相似文献
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Satoshi Suetsugu Nobusuke Muto Misa Horinouchi Dr. Chihiro Tsukano Prof. Dr. Yoshiji Takemoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8059-8062
A new method has been developed for the synthesis of tetrahydro‐2H‐fluorenes based on a Pd(0)‐catalyzed benzylic C(sp3)?H functionalization. Importantly, the success of the cyclization step was dependent on there being substituents at the two positions ortho to the benzylic group to avoid an undesired C(sp2)?H functionalization. This method was subsequently used to prepare the right‐hand fragment of the hexacyclic triterpenoid benzohopanes, and therefore represents a powerful tool for the construction of the related compounds. 相似文献
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Ligand Bite Angle‐Dependent Palladium‐Catalyzed Cyclization of Propargylic Carbonates to 2‐Alkynyl Azacycles or Cyclic Dienamides 下载免费PDF全文
David S. B. Daniels Alison S. Jones Dr. Amber L. Thompson Dr. Robert S. Paton Dr. Edward A. Anderson 《Angewandte Chemie (International ed. in English)》2014,53(7):1915-1920
The regioselectivity of the palladium‐catalyzed cyclization of propargylic carbonates with sulfonamide nucleophiles is critically dependent on the bite angle of the bidentate phosphine ligand. Ligands with small bite angles favor attack on the central carbon atom of an allenylpalladium intermediate to afford cyclic dienamide products, whereas the use of those with large bite angles leads to alkynyl azacycles, with high stereoselectivity. A computational analysis of the reaction pathway is also presented. 相似文献
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Nathalie Pinto Mathilde Neel Armen Panossian Dr. Pascal Retailleau Dr. Gilles Frison Dr. Arnaud Voituriez Dr. Angela Marinetti Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(3):1033-1045
The planar chiral 2‐phospha[3]ferrocenophane I has been shown to be the first efficient nucleophilic organocatalyst for the enantioselective synthesis of cyclopentenylphosphonates, through [3+2] cyclizations between diethyl allenylphosphonate and α,β‐unsaturated ketones. The same catalyst has also been applied to the highly enantioselective [3+2] cyclizations of allenic esters with dibenzylideneacetone and analogous bis‐enones, leading to functionalised cyclopentenes with either monocyclic or spirocyclic structures (ee 84–95 %). It has been shown that the residual enone functions in the resulting cyclopentenes can be involved in subsequent cyclization steps to afford unprecedented C2‐symmetric bis‐cyclopentenylketones. In order to provide insight into the behaviour of FerroPHANE I as a chiral catalyst in [3+2] cyclisations, the energetically most favoured isomers of the key phosphine‐allene adduct have been calculated by DFT methods. Factors likely to control the chiral induction process are highlighted. 相似文献
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Base‐Promoted/Gold‐Catalyzed Intramolecular Highly Selective and Controllable Detosylative Cyclization 下载免费PDF全文
Chenghao Zhu Dr. Lin Qiu Guangyang Xu Dr. Jian Li Prof. Dr. Jiangtao Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):12871-12875
A highly selective, controllable and synthetically useful base‐promoted intramolecular detosylative cyclization of bis‐N‐tosylhydrazones has been achieved, affording N‐containing heterocycles and cyclic olefins under transition‐metal‐free or gold‐catalyzed procedures, respectively. Moreover, an effective and practical metal‐free or gold‐catalyzed approach to synthesize polycyclic aromatic compounds is also reported. 相似文献
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A novel palladium‐catalyzed domino reaction of 1‐bromo‐2‐(cyclopropylidenemethyl)benzene and 2‐alkynylbenzenamine is reported, which generates 2‐(naphthalen‐2‐yl)benzenamines and 5H‐indeno[1,2‐c]quinolines via 6‐endo and 5‐exo cyclization, respectively. The regioselectivity for the final outcome can be affected by phosphine and N‐heterocyclic carbene ligands. 相似文献
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Benito Alcaide Prof. Dr. Pedro Almendros Dr. Teresa Martínez del Campo Rocío Carrascosa 《化学:亚洲杂志》2008,3(7):1140-1145
A mild, palladium(II)‐catalyzed reaction of α‐allenols with α‐allenic esters in a heterocyclization/cross‐coupling sequence, applicable to a wide range of substitution patterns, has been developed for the preparation of 2,3,4‐trifunctionalized 2,5‐dihydrofurans. Our studies indicate high levels of chemo‐ and regiocontrol. The possibility of using optically active substrates as well as substrates of increased steric demand, such as tertiary α‐allenols, makes this novel sequence of heterocyclization/cross‐coupling an attractive method in organic synthesis. The current mechanistic hypothesis invokes a regiocontrolled palladium(II)‐mediated intramolecular oxypalladation of the free allenol component, that then undergoes a cross‐coupling reaction with the allenic ester partner, followed by a trans‐β‐deacyloxypalladation with concomitant regeneration of the PdII species. 相似文献