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Although post-functionalization is extensively used to introduce diverse functional groups into supramolecular polymers (SPs) in solution, post-functionalization of SPs on surfaces still remains unexplored. Here we achieved the on-surface post-functionalization of two SPs derived from 5,10,15-tri-(4-pyridyl)-20-bromophenyl porphyrin (Br-TPyP) via cross-coupling reactions on Au(111). The ladder-shaped, Cu-coordinated SPs preformed from Br-TPyP were functionalized through Heck reaction with 4-vinyl-1,1'-biphenyl. In the absence of Cu, Br-TPyP formed chiral SPs as two enantiomers via self-assembly, which were functionalized via divergent cross-coupling reaction with 4-isocyano-1,1'-biphenyl (ICBP). Surprisingly, this reaction was discovered as an enantioselective on-surface reaction induced by the chirality of SPs. Mechanistic analysis and DFT calculations indicated that after debromination of Br-TPyP and the first addition of ICBP, only one attack direction of ICBP to the chiral SP intermediate is permissive in the second addition step due to the steric hindrance, which guaranteed the high enantioselectivity of the reaction.

[3]Radialenes are the smallest carbocyclic structures with unusual topologies and cross-conjugated π-electronic structures. Here, we report a novel [1+1+1] cycloaddition reaction for the synthesis of aza[3]radialenes on the Ag(111) surface, where the steric hindrance of the chlorine substituents guides the selective and orientational assembling of the isocyanide precursors. By combining scanning tunneling microscopy, non-contact atomic force microscopy, and time-of-flight secondary ion mass spectrometry, we determined the atomic structure of the produced aza[3]radialenes. Furthermore, two reaction pathways including synergistic and stepwise are proposed based on density functional theory calculations, which reveal the role of the chlorine substituents in the activation of the isocyano groups via electrostatic interaction.

Multinuclear heterometallic nanoclusters with controllable stoichiometry and structure are anticipated to possess promising catalytic, magnetic, and optical properties. Heterometallic nanoclusters with precise stoichiometry of Bi3 Cu4 and Bi7 Cu12 can be stabilized in the scaffold of two-dimensional metal-organic networks on a Cu(111) surface through on-surface metallosupramolecular self-assembly processes. The atomic structures of the nanoclusters were resolved using scanning tunneling microscopy and density functional theory calculations. The nanoclusters feature highly symmetric planar hexagonal shapes and core-shell charge modulation. The clusters are arranged as triangular lattices with a periodicity that can be tuned by choosing molecules of different size. This work shows that on-surface metallosupramolecular self-assembly creates unique possibilities for the design and synthesis of multinuclear heterometallic nanoclusters.

Using scanning tunnelling microscopy (STM), we demonstrate that Au-pyridyl coordination can be used to assemble two-dimensional coordination network structures on metal surfaces. The polymorphism of the coordination network structures can be manipulated at both the micro- and nanoscale. Using the same organic ligand, we assembled two distinct polymorphic network structures, which were assisted by threefold Au-pyridyl coordination on Ag(111) with predeposited Au atoms (α-network), and by twofold Au-pyridyl coordination on Au(111) (β-network), respectively. Specifically on the Au(111) surface, single-oriented β-network domains as large as ≈400 nm were selected by thermal annealing. We ascribe this global control strategy to distinct Au bonding modes tuned by molecule-substrate interactions. Using an STM tip, we succeeded in creating α-network domains (≈10 nm) locally within the homogeneous β-network domain areas on Au(111) in a controlled manner.

A convenient palladium-catalyzed tandem reaction of aryl iodides and salicyl N-tosylhydrazones has been achieved to afford a series of compounds containing the novel spiro[benzofuran-3,2′-chromene] scaffold in moderate to good yields. This efficient catalytic reaction, which tolerates various functional groups, combines alkyne-based 5-exo-dig cyclization, palladium(II) carbene migratory insertion and intramolecular cyclization, generating three new bonds in one reaction.

Two tunable cascade reactions of alkynols and alkynes have been developed by combining Sc(OTf)3 and rhodium catalysis. In the absence of H2O, an endo-cycloisomerization/C-H activation cascade reaction provided 2,3-dihydronaphtho[1,2-b]furans in good to high yields. In the presence of H2O, the product of alkynol hydration underwent an addition/C-H activation cascade reaction with an alkyne, which led to the formation of 4,5-dihydro-3H-spiro[furan-2,1'-isochromene] derivatives in good yields under mild reaction conditions. Mechanistic studies of the cascade reactions indicated that the rate-determining step involves C-H bond cleavage and that the hydration of the alkynol plays a key role in switching between the two reaction pathways.

Cross-coupling is of great importance in organic synthesis. Here it is demonstrated that cross-coupling of aryl-bromide and porphyrin-bromide takes place on aA u(111 )s urface in vacuo. The products are oligomers consisting of porphyrin moieties linked by p-phenylene at porphyrin's meso-positions. The ratio of the cross-coupled versus homocoupled bonds can be regulated by the reac- tant concentrations. Kinetic Monte Carlo simulations were applied to determine the activatio nb arrier .I ti se xpected that this reaction can be employed in other aryl-bromide precursors for designing alternating co-polymers incorpo- rating porphyrin and other functional moieties.

The ruthenium-catalyzed alkenylation of arenes with alkynes or alkenes has been achieved by using 1,2,3-triazole as the directing group for the C–H activation. With [Ru(p-cymene)Cl2]2 as the catalyst and Cu(OAc)2·H2O and AgSbF6 as additives, various triazole-substituted arenes reacted readily with a range of internal alkynes or terminal alkenes to afford di- or monoalkenylated arenes with high regioselectivity and in moderate-to-excellent yields.

Cellular redox status plays a key role in mediating various physiological and developmental processes often through modulating activities of redox-sensitive proteins. Various stresses trigger over-production of reactive oxygen/nitrogen species which lead to oxidative modifications of redox-sensitive proteins. Identification and characterization of redox-sensitive proteins are important steps toward understanding molecular mechanisms of stress responses. Here, we report a high-throughput quantitative proteomic approach termed OxiTRAQ for identifying proteins whose thiols undergo reversible oxidative modifications in Arabidopsis cells subjected to oxidative stress. In this approach, a biotinylated thiol-reactive reagent is used for differential labeling of reduced and oxidized thiols. The biotin-tagged peptides are affinity purified, labeled with iTRAQ reagents, and analyzed using a paralleled HCD-CID fragmentation mode in an LTQ-Orbitrap. With this approach, we identified 195 cysteine-containing peptides from 179 proteins whose thiols underwent oxidative modifications in Arabidopsis cells following the treatment with hydrogen peroxide. A majority of those redox-sensitive proteins, including several transcription factors, were not identified by previous redox proteomics studies. This approach allows identification of the specific redox-regulated cysteine residues, and offers an effective tool for elucidation of redox proteomes.

A Rh(III)-catalyzed coupling/cyclization cascade reaction is described, which involves arylimidates and diazo compounds and proceeds via intermolecular C–C bond formation and subsequent intramolecular C–N bond formation. Mechanistic investigation revealed that the reaction is a two-step process: the initial Rh(III)-catalyzed coupling/cyclization proceeds very fast and the following dehydration is rather slow. The reaction provides a direct approach to isoquinolines and isoquinolin-3-ols without any oxidants.

A convenient palladium-catalyzed tandem reaction of aryl iodides and salicyl N-tosylhydrazones has been achieved to afford a series of compounds containing the novel spiro[benzofuran-3,2′-chromene] scaffold in moderate to good yields. This efficient catalytic reaction, which tolerates various functional groups, combines alkyne-based 5-exo-dig cyclization, palladium(II) carbene migratory insertion and intramolecular cyclization, generating three new bonds in one reaction.

Two tunable cascade reactions of alkynols and alkynes have been developed by combining Sc(OTf)3 and rhodium catalysis. In the absence of H2O, an endo-cycloisomerization/C-H activation cascade reaction provided 2,3-dihydronaphtho[1,2-b]furans in good to high yields. In the presence of H2O, the product of alkynol hydration underwent an addition/C-H activation cascade reaction with an alkyne, which led to the formation of 4,5-dihydro-3H-spiro[furan-2,1'-isochromene] derivatives in good yields under mild reaction conditions. Mechanistic studies of the cascade reactions indicated that the rate-determining step involves C-H bond cleavage and that the hydration of the alkynol plays a key role in switching between the two reaction pathways.

A multicomponent cascade reaction is described that provides concise access to the trifluoroethyl isoquinolines using a Rh(III)–Cu(II) bimetallic system and readily available Togni’s reagent. The system tolerates various vinyl azides and internal alkynes. Experimental results suggest that Togni’s reagent might act as a CF3 radical supplier.

Various [2-(arylethinyl)phenyl]methanols are reacting with 1-(1-azidovinyl)arenes and hetarenes to deliver polycyclic pyran-based indeno[1,2-c]isochromene scaffolds in moderate to high yields.

The microwave-assisted substitution of β-dicarbonyl compounds with secondary alcohols has been achieved efficiently, using very cheap fluoroboric acid (HBF4) as the catalyst. For various β-dicarbonyl compounds and a series of secondary alcohols, the direct substitution gives high yields after only 5 min of microwave irradiation.

A dicationic dichloro-bipyridine-ruthenium complex shows very high catalytic activity in redox isomerization of allylic alcohols but a relatively low one in transfer hydrogenation of ketones; surprisingly, the analogous dimethyl-bipyridine-ruthenium complex shows reverse catalytic activities in the two reactions.

The new ruthenium complex [Ru(N(3)P)(OAc)][BPh(4)] (4), in which N(3)P is the N,P mixed tetradentate ligand N,N-bis[(pyridin-2-yl)methyl]-[2-(diphenylphosphino)phenyl]methanamine was synthesized. The complex was found to be catalytically active for the endo cycloisomerization of alkynols. The catalytic reactions can be used to synthesize five-, six-, and seven-membered endo-cyclic enol ethers in good to excellent yields. A catalytic cycle involving a vinylidene intermediate was proposed for the catalytic reactions. Treatment of complex 4 with PhC[triple bond]CH and H(2)O gave the alkyl complex [Ru(CH(2)Ph)(CO)(N(3)P)][BPh(4)] (30), which supports the assumption that the catalytic reactions involve addition of a hydroxyl group to the C=C bond of vinylidene ligands.

The perchlorate salt of the dicationic bipy-ruthenium complex cis-[Ru(6,6'-Cl2bipy)2(H2O)2]2+ effectively catalyzes addition of beta-diketones to secondary alcohols and styrenes to yield the alpha-alkylated beta-diketones. In a catalytic addition reaction of acetylacetone to 1-phenylethanol, the kappa2-acetylacetonate complex [Ru(6,6'-Cl2bipy)2(kappa2-acac)]ClO4 was isolated after the catalysis; this complex is readily synthesized by reacting cis-[Ru(6,6'-Cl2bipy)2(H2O)2](ClO4)2 with acetylacetone. [Ru(6,6'-Cl2bipy)2(kappa2-acac)]ClO4 is unreactive toward 1-phenylethanol in the presence of HClO4; it also fails to catalyze the addition of acetylacetone to 1-phenylethanol. On the basis of these observations, it is proposed and confirmed by independent experiments that the catalytic addition of beta-diketones to the secondary alcohols is in fact catalyzed by the Brønsted acid HClO4, which is generated by the reaction of cis-[Ru(6,6'-Cl2bipy)2(H2O)2](ClO4)2 with the beta-diketone.

The title compounds are obtained by Pd-catalyzed reaction of 4-aryl-3-iodo-2H-chromenes (II), (IV) and (VI) with salicylaldehyde-derived tosylhydrazones (I) in modest to good yields.

A tetradentate nitrogen-phosphorus ligand is used for the ruthenium-catalyzed title reaction with high exo-selectivity.

In the title transformation, the amides (I) and (IX) function as the directing group in C—H activation, constraining the substrates to undergo formation of an intermolecular C—C bond and an intramolecular C—O bond.

The N—H imidate group efficiently acts as a directing group in Ru-catalyzed C—H activation allowing the regio- and stereoselective synthesis of methyleneisoindolinones.

Various substituted 1,4-disubstituted triazoles (III) are obtained by highly efficient Ru-catalyzed click reaction between terminal alkynes and organic azides.

The ruthenium-catalyzed alkenylation of arenes with alkynes or alkenes has been achieved by using 1,2,3-triazole as the directing group for the C–H activation. With [Ru(p-cymene)Cl2]2 as the catalyst and Cu(OAc)2·H2O and AgSbF6 as additives, various triazole-substituted arenes reacted readily with a range of internal alkynes or terminal alkenes to afford di- or monoalkenylated arenes with high regioselectivity and in moderate-to-excellent yields.

Potassium tert -butoxide ( t -BuOK) was found to be an effective catalyst for the cyclization of aromatic alkynols and alkynylamines. In the presence of 10 mol % t -BuOK, a range of alkynols were converted to the corresponding exo -cyclic enol ethers as pure Z -stereoisomers with 100% selectivity and moderate to excellent yields. Moreover, the cyclization of alkynylamines was also achieved to afford indoles and isoindolin-1-ones in good yields.

The presented tandem reaction involves cycloisomerization, formal [4 + 2] cycloaddition and an elimination process.

The result of the title cascade reaction of alkynols with imines depends on the solvent used (DMSO or THF).

A mild, efficient, regioselective and redox-neutral annulation of O-benzoylhydroxylamines and internal alkynes is developed.

The title reaction provides highly concise and effective routes to related complex compounds including natural product derivatives.

Intermolecular benzylic methylene functionalization of exo-cyclic enol ethers has been achieved using imines as reagents and potassium tert-butoxide as the catalyst. Depending on the solvent used, the reaction proceeds by two pathways. In THF, an addition/elimination reaction of exo-cyclic enol ethers with imines provides dihydroisobenzofuran derivatives in good yield. In DMSO, an addition/ring-opening/cyclization cascade reaction occurs with unexpected cleavage of C–O and C–C bonds, affording isoquinolin-1(2H)-one products in high yield under ambient reaction conditions.

In addition to the cycloaddition reactions of terminal alkynes with aromatic or aliphatic azides (18 examples), alcohol (VII) is formed by both cycloaddition and transfer hydrogenation reactions in the presence of 1,4-butanediol and the ruthenium catalyst.

The investigation of a broad spectrum reveals that there is no advantage of a microwave version compared to conventional conditions.

Two versions including triflic acid adsorbed on silica gel are used for the title reaction and generally similar yields are produced.

If the reaction is conducted in the presence of primary alcohols the respective yields are either low or the reaction does not proceed at all.

A Ru(II)—dichlorobipyridine complex (Ia) efficiently catalyzes the redox isomerization of terminal and internal allylic alcohols to give the corresponding ketones, e.g. (III), (V) or (VII), in high to excellent conversion.

It is found that HClO4 and silica gel supported HClO4 efficiently promote the addition of β-dicarbonyl compounds to secondary alcohols and alkenes.

Five-, six-, and seven-membered endocyclic enol ethers are prepared in good to excellent yield by the title reaction.

Twenty-two examples for the title reaction are presented, affording the corresponding products in moderate to excellent yields under solvent-free conditions or in nitromethane.

Easily accessible N-(p-tolylsulfonyl)-1,2-diphenylethylenediamine-(TsDPEN-)derived organic–inorganic hybrid ligands were prepared and applied to the heterogeneous asymmetric transfer hydrogenation in traditional HCO2H/NEt3 and in water with HCO2Na as the hydrogen source and sodium dodecyl sulfate (SDS) as the phase-transfer catalyst. The reactions demonstrated high catalytic activities and excellent enantioselectivities for most aromatic ketones and the imine tested, with results similar to those in homogeneous catalysis.In particular, this heterogeneous catalyst can be readily recovered and used in multiple consecutive catalytic runs with the high enantioselectivity maintained both in HCO2H/NEt3 and in water. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)