A solid phase carbohydrate library was synthesized and screened against Bauhinia purpurea lectin. The library, which contains approximately 1300 di- and trisaccharides, was synthesized with chemical encoding on TentaGel resin so that each bead contained a single carbohydrate. Two ligands that bind more tightly to the lectin than Gal-beta-1,3-GalNAc (the known ligand) have been identified. The strategy outlined can be used to identify carbohydrate-based ligands for any receptor; however, because the derivatized beads mimic the polyvalent presentation of cell surface carbohydrates, the screen may prove especially valuable for discovering new compounds that bind to proteins participating in cell adhesion.

We review here new developments in decreasing the catalyst loadings in palladium-catalyzed C-C bond-formation reactions to mol ppm or mol ppb levels.T his decreasest he cost of the catalyst and the toxicity of the reactions ystem, making the reactionm ore attractive to industry.T he Heck reaction, Sonogashira reaction, Suzuki-Miyaurac rosscoupling reaction, other cross-coupling reactions,a nd allylic arylation reactions are separately discussedt o show clearly the progress made in each type of reaction. Apart from the catalyst loading, the other parameters of the reaction( temperature,s olvent, etc.) are brieflyd iscussed to illustrate the shift toward greenerc onditions.F or most reactions,t his shift is underway or wella dvanced, andc atalyst loadings have been decreasedt ob elow 1mol ppm. An abundance of catalytic systems are now available,a nd it is sometimes difficult to identify the best one,b ecause the substratese xamined can vary widely from publication to publication.I nt he future,e mphasis should be placed on the studyingt he full scope of the reaction at mol ppm catalyst loadings,r athert han examining af ew examples at these levels during the reaction-optimization process.1I ntroduction 2M izoroki-Heck Coupling 3S onogashira Coupling 4S uzuki-MiyauraCross-Coupling 5O ther Cross-Coupling Reactions 6A llylic Arylation 7C onclusions

Self-assembly of copper sulfate and a poly(imidazole-acrylamide) amphiphile provided a highly active, reusable, globular, solid-phase catalyst for click chemistry. The self-assembled polymeric Cu catalyst was readily prepared from poly(N-isopropylacrylamide-co-N-vinylimidazole) and CuSO(4) via coordinative convolution. The surface of the catalyst was covered with globular particles tens of nanometers in diameter, and those sheetlike composites were layered to build an aggregated structure. Moreover, the imidazole units in the polymeric ligand coordinate to CuSO(4) to give a self-assembled, layered, polymeric copper complex. The insoluble amphiphilic polymeric imidazole Cu catalyst with even 4.5-45 mol ppm drove the Huisgen 1,3-dipolar cycloaddition of a variety of alkynes and organic azides, including the three-component cyclization of a variety of alkynes, organic halides, and sodium azide. The catalytic turnover number and frequency were up to 209000 and 6740 h(-1), respectively. The catalyst was readily reused without loss of catalytic activity to give the corresponding triazoles quantitatively.

Metalloenzymes are essential proteins with vital activity that promote high-efficiency enzymatic reactions. To ensure catalytic activity, stability, and reusability for safe, nontoxic, sustainable chemistry, and green organic synthesis, it is important to develop metalloenzyme-inspired polymer-supported metal catalysts. Here, we present a highly active, reusable, self-assembled catalyst of poly(imidazole-acrylamide) and palladium species inspired by metalloenzymes and apply our convolution methodology to the preparation of polymeric metal catalysts. Thus, a metalloenzyme-inspired polymeric imidazole Pd catalyst (MEPI-Pd) was readily prepared by the coordinative convolution of (NH(4))(2)PdCl(4) and poly[(N-vinylimidazole)-co-(N-isopropylacrylamide)(5)] in a methanol-water solution at 80 °C for 30 min. SEM observation revealed that MEPI-Pd has a globular-aggregated, self-assembled structure. TEM observation and XPS and EDX analyses indicated that PdCl(2) and Pd(0) nanoparticles were uniformly dispersed in MEPI-Pd. MEPI-Pd was utilized for the allylic arylation/alkenylation/vinylation of allylic esters and carbonates with aryl/alkenylboronic acids, vinylboronic acid esters, and tetraaryl borates. Even 0.8-40 mol ppm Pd of MEPI-Pd efficiently promoted allylic arylation/alkenylation/vinylation in alcohol and/or water with a catalytic turnover number (TON) of 20,000-1,250,000. Furthermore, MEPI-Pd efficiently promoted the Suzuki-Miyaura reaction of a variety of inactivated aryl chlorides as well as aryl bromides and iodides in water with a TON of up to 3,570,000. MEPI-Pd was reused for the allylic arylation and Suzuki-Miyaura reaction of an aryl chloride without loss of catalytic activity.

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A step closer to the ideal oxidation of alcohols: Catalytic oxidation of alcohols in water under atmospheric oxygen was achieved by use of an amphiphilic resin‐dispersion of a nanopalladium catalyst (see scheme). This system combines high catalytic activity owing to the large surface area of the nanoparticles and water‐based reactivity provided by the amphiphilicity of the polystyrene—poly(ethylene glycol) matrix.

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