A mild and efficient ligand-free Suzuki-Miyaura coupling reaction catalyzed by heterogeneous Pd/C was developed. Aryl bromides and triflates undergo the cross-coupling with aryl boronic acids in excellent yields without the presence of any additives in aqueous media at room temperature. Aryl vinyl boronic acids are also applicable to this coupling reaction and provide the trans-stilbene derivatives in high yields. The application of wet-type Pd/C to the coupling reaction was achieved without any loss of activity under aerobic conditions, and the reuse of Pd/C is feasible for a fifth run without significant loss of activity. Inductively coupled plasma (ICP) mass-spectrometric analysis of the filtrate from the reaction mixture of 4-bromonitrobenzene with phenylboronic acid demonstrated that the palladium metal hardly leached into the solution within the limits of the detector (<1 ppm), thus suggesting that the present Suzuki-Miyaura reaction proceeded by heterogeneous catalysis.

An efficient and practical arene hydrogenation procedure based on the use of heterogeneous platinum group catalysts has been developed. Rh/C is the most effective catalyst for the hydrogenation of the aromatic ring, which can be conducted in iPrOH under neutral conditions and at ordinary to medium H(2) pressures (<10 atm). A variety of arenes such as alkylbenzenes, benzoic acids, pyridines, furans, are hydrogenated to the corresponding cyclohexyl and heterocyclic compounds in good to excellent yields. The use of Ru/C, less expensive than Rh/C, affords an effective and practical method for the hydrogenation of arenes including phenols. Both catalysts can be reused several times after simple filtration without any significant loss of catalytic activity.

[Structure: see text] A Pd/C-catalyzed chemoselective hydrogenation using diphenylsulfide as a catalyst poison has been developed. This methodology selectively hydrogenates olefin and acetylene functionalities without hydrogenolysis of aromatic carbonyls and halogens, benzyl esters, and N-Cbz protective groups.

An environmentally benign oxidation of alcohols in water using iodosobenzene (PhI=O) or a polymer‐supported (diacetoxyiodo)benzene (PSDIB) with KBr has been achieved (see scheme). This method results in the catalytic activation of a variety of sluggishly reactive and/or sparsely soluble hypervalent iodine reagents in water under neutral conditions.

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Over the past decade, the use of hypervalent iodine reagents [1] has gained importance as a safe alternative to heavy-metal reagents for performing a variety of organic transformations. In view of recent demands for ecologically friendly chemical processes in the agrochemical and pharmaceutical industries, polymer-supported hypervalent iodine reagents should be a new and useful tool as a result of their versatility, low toxicity, high yields, simple work-up procedures, and recyclability. Accordingly, Togo and co-workers, [1h, 2] Ley and co-workers, [3] and we [4] demonstrated that both poly(diacetoxyiodo)styrene (PDAIS) [5] and polybis(trifluoroacetoxyiodo)styrene (PBTIS) exhibit reactivities similar to those of phenyliodine diacetate (PIDA) and phenyliodine bis(trifluoroacetate) (PIFA), respectively, and utilized them as environmentally benign replacements for I III reagents such as PIDA, PIFA, and iodosyl benzene (PhIO) (Scheme 1).Despite the utility and versatility of these polymersupported reagents, they still have several drawbacks: 1) the loading efficiency of I III sites is difficult to control, which has made the marketing of polymer-supported iodine reagents difficult; 2) the degradative loss of resin is accompanied by benzylic oxidation of the polystyrene chain after repeated use; and 3) they are much less reactive than the corresponding monomeric forms owing to steric hindrance of the reactive sites as well as their low solubility in various solvents. Therefore, slightly vigorous conditions and/or an excess amount of reagents are generally needed. Herein we report the preparation and characterization of a novel, recyclable, and nonpolymeric hypervalent iodine(iii) reagent, 1,3,5,7-tetrakis[4-(diacetoxyiodo)phenyl] adamantane (1), and its derivatives. As a part of our continuing research into the development of new hypervalent iodine compounds, we planned to synthesize an unprecedented tetrahedral I III compound 1, which should be a precursor to build a unique hypervalent iodine-based supramolecular structure as well as a new oxidizing agent. We prepared 1,3,5,7-tetrakis(4-iodophenyl)-adamantane (2) in good yield in two steps from commercially available 1-bromoadamantane according to a literature procedure.[6] Oxidation of 2 by conventional methods [7] with peracetic acid (30 % H 2 O 2 and acetic anhydride), sodium perborate (NaBO 3 ) in acetic acid, or sodium periodate (NaIO 4 ) unexpectedly gave 1 in low yield, accompanied by poorly soluble and unidentifiable polymeric products. After further investigations, we finally succeeded in synthesizing 1 in 97 % yield by using m-chloroperbenzoic acid (MCPBA) in CH 2 Cl 2 /AcOH (1:1) under dilute conditions (Scheme 2).Adamantane 1 was fully characterized by single-crystal Xray analysis [8] as well as elemental and spectroscopic analysis. A single crystal of 1 suitable for X-ray crystallographic analysis was obtained through slow growth by the vapor diffusion from CH 2 Cl 2 /AcOH/hexanes. Figure 1 reveals the geometry around the iodine in 1 to be a p...

An effective and applicable deuteration method for aromatic rings using Pt/C–D2O–H2 system was established. Especially, phenol was fully deuterated even at room temperature, and other electron-rich aromatic nuclei were efficiently deuterated under mild conditions. The scope and limitations of the presence method and its application to the synthesis of deuterium-labeled biologically active compounds and deuterium-labeled building blocks for practical multi-gram scale syntheses are reported.

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