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A piperidine-derived tetraalkylammonium salt with a non-coordinating counteranion worked as an effective hydrogen-bonding catalyst in an aza-Diels–Alder reaction of imines and a Danishefsky diene. The hydrogen-bonding interaction between the ammonium salt and an imine was observed as part of a 1H NMR titration study.

Tin(IV) bromide was found to act as an efficient Lewis acid catalyst for the Friedel–Crafts type dehydrative alkylation reaction of diarylmethanols with 2-naphthol derivatives under mild conditions. The effects of the substituents on the substrates were systematically evaluated, and the reaction could be applied to a variety of substrates by tuning the conditions depending on the electronic properties of the starting materials.

Starting from the glucose-derived δ-lactone and the functionalized aryl bromide, the first total synthesis of naturally occurring paecilomycin B was achieved via functionalized aryl-β-C-glycoside synthesis using 2,4,6-triisopropylphenyllithium under Barbier-type reaction conditions and ring-closing metathesis as the key steps.

The title reaction affords a broad range of benzyl-alkyl, -allyl, -benzyl, and aryl ethers via a SN1-type reaction mechanism.

The iodocyclization of ethoxyethyl ethers to ynamides was completed within three seconds. The corresponding benzo[b]furans were obtained in high yields (84%–quant.) under mild conditions.

With a goal of the total synthesis of polymaxenolide, the first hybrid marine natural product, the model studies for constructing the dihydropyran portion based on the originally proposed biosynthesis (C–C bond formation followed by dehydrative cyclization) and the synthesis of the lower portion (the C1–C3, C7–C17 portion) based on an iodide-induced Morita–Baylis–Hillman type reaction (a three-component assembly) followed by Suzuki–Miyaura cross-coupling are described.

Several recent efforts concerning post-metallocene Group 4 metal complexes incorporating mixed donor [OSSO]-type tetradentate bis(phenolato) ligands are reviewed. These [OSSO]-type ligands can be mainly classified as 5–5–5, 5–6–5 and 6–5–6 arrays of chelate rings toward central metals. As the main topics are described the design and unique coordination chemistry of the [OSSO]-type ligands and catalytic activities of the resultant titanium, zirconium, and hafnium complexes as single-site catalysts for polymerizations and copolymerizations of olefins.

The competitive complexation experiment indicates that cis compound (VIII) forms the complex with AgOTf more preferably than trans compound (XI).

The kinetic resolution of racemic alcohols (I) with phenylpropanoic acid (II) is examined and the optimized structure of the oxazole part in substrates (I) is determined.

The first efficient non-enzymatic method for providing optically active 1-heteroarylalkanol derivatives by kinetic resolution is given.

Two novel elemanolide dimers, vernodalidimers A (1) and B (2), possessing a rare tricyclic ortho ester moiety, were isolated from the seeds of Vernonia anthelmintica. Their structures were elucidated by 1D and 2D NMR data and CD spectra. Vernodalidimers A (1) and B(2) exhibited potent cell growth inhibitory activity against HL-60 cells (IC(50) 0.72 and 0.47 mu M, respectively).

A widely applicable method is developed via generation of mixed anhydrides followed by reaction with bis(9-phenanthryl)methanol in the presence of (+)-benzotetramisole as the catalyst.

1,2-Oxaplatinacycles (III) are formed unexpectedly from 2-hydroxybenzyl sulfide derivatives (I) by bond cleavage mediated by platinum(0).

Since the isolation of brevetoxin-B, a red tide toxin, many bioactive marine natural products featuring synthetically challenging trans-fused polycyclic ether ring systems have been reported. We have developed SmI2-induced cyclization of β-alkoxyacrylate with aldehyde, affording 2,6-syn-2,3-trans-tetrahydropyran (THP) or 2,7-syn-2,3-trans-oxepane with complete stereoselection, as a key reaction of efficient iterative and bi-directional strategies for the construction of these polycyclic ethers. This reaction is also applicable to the synthesis of 3-, 5-, and 6-methyl-THPs and 3,5-dimethyl-THP. The synthesis of 2-methyl- and 2,6-dimethyl-THPs was accomplished by means of a unique methyl insertion. Recently, the SmI2-induced cyclization was extended to similar reactions using β-alkoxyvinyl sulfone and sulfoxide. Reaction of (E)- and (Z)-β-alkoxyvinyl sulfone-aldehyde afforded 2,6-syn-2,3-trans- and 2,6-syn-2,3-cis- THPs, respectively. Reaction of (E)-β-alkoxyvinyl (R)- and (S)-sulfoxides gave 2,6-anti-2,3-cis- and 2,6-syn-2,3-trans-THPs, respectively. Reaction of (Z)-β-alkoxyvinyl (R)-sulfoxides gave 2,6-syn-2,3-cis-THP and an olefinic product, while that of (Z)-β-alkoxyvinyl (S)-sulfoxide afforded a mixture of many products. These SmI2-induced cyclizations have been applied to the total syntheses of various natural products, including brevetoxin-B, mucocin, pyranicin, and pyragonicin. Synthetic studies on gambierol and maitotoxin are also introduced. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 10: 159–172; 2010: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900027

Papuabalanol A (Ib) shows moderate vasodilator effect on rat aorta while papuabalanol B (Ia) shows potent inhibition of mushroom tyrosinase and anti-melanogenesis in B16 mouse melanoma cells.

Treatment of π-electron sufficient aromatic heterocycles such as title compounds with aryl bromides in the presence of tetrakis(triphenylphosphine)palladium gave the corresponding 2-aryl aromatic heterocycles.

Recent progress in the methodology for stereoselective synthesis of the 1,3-polyol functions is reviewed. Strategies for the synthesis of the extended 1,3-polyol chain are also described

Dehydration of the four diastereomers of tetrahydropyran 8-11 involving the 4-hydroxyl and 5-methyl groups with diethylazodicarboxylate-PPh 3 -toluene was undertaken to clarify the relation between the configurations of these substituents and the direction of dehydration. Compound 8 with 4β(equatorial)-hydroxyl and 5β(axial)-methyl groups was found to give the trisubstituted olefin 12 exclusively, and the isomers 13 and 14 were shown to be produced from 9 and 11, respectively, with high selectivity. The mechanisms involved are discussed

The title compound was prepared in one step from commercially available 2-amino-6-methoxybenzothiazole by using the Sandmeyer cyanation reaction. The result enabled us to synthesize firefly luciferin effectively from this amino compound through three steps in 36% overall yield.

Improved synthetic methods of firefly luciferin derivatives, such as 6-O-alkanoylluciferins and 6-O-phosphonoluciferin, are described. These derivatives proved to be useful as substrates for the bioluminescent assay of hydrolytic enzymes such as carboxylic esterase and alkaline phosphatase. The synthetic methods previously reported gave fairly low yields because of direct derivatization of unstable luciferin itself and are difficult to be applied to large-scale synthesis because of unavoidable HPLC purification. We first modified the hydroxyl group of 2-cyano-6-hydroxybenzothiazole and then condensed the resulting stable products with D-cysteine to give the appropriate derivatives in good yields without HPLC purification. 6-O-Phosphonoluciferin was unstable as free acid form but stable as its sodium salt.

Methane reacts with CO to give acetic acid in good yield by the CuSO4 and/or Pd(OCOEt)2 catalysts via C-H bond activation. This reaction has an advantage over the method which uses methanol and rhodium catalysts, in that cheap methane and copper catalysts can be used. Propane also reacts with CO to give butyric acids.

A stable 14-membered polyketide lactone having a C-methyl group at C-13 has been synthesized and elucidated to have the bis-enol structure by X-ray crystallographic analysis, and its hydride reduction to the tetraols has also been described.

The first total synthesis of herbimycin A (1), the benzoquinoid ansamycin antibiotic, has been accomplished by coupling two segments of the aliphatic ansa-chain 2 and the aromatic chromophore 3, elucidating the absolute stereochemistry.

The synthesis and the structure of silicon carbide-silicon nitride (SiC-Si[sub 3]N[sub 4]) composite ultrafine particles have been studied. SiC-Si[sub 3]N[sub 4] composite ultrafine particles were prepared by irradiating a SiH[sub 4], C[sub 2]H[sub 4], and NH[sub 3] gas mixture with a CO[sub 2] laser at atmospheric pressure. The composition of composite powders changed with the reactant gas flow rate. The carbon and nitrogen content of the powder could be controlled in a wide range from 0 to 30 wt%. The composite powder, which contained 25.3 wt% carbon and 5.8 wt% nitrogen, had a [beta]-SiC structure. As the nitrogen content increased, SiC decreased and amorphous phase, Si[sub 3]N[sub 4], Si appeared. The results of XPS and lattice constant measurements suggested that Si, C, and N atoms were intimately mixed in the composite particles.

A novel methodology for the controlled synthesis of 2,6-dideoxy oligosaccharides by combinational use of an activated 2,6-anhydro-2-thio sugar and a deactivated 2,6-anhydro-2-sulfinyl sugar, both of which have a same leaving group at anomeric position, has been demonstrated.

Enzyme-mediated stereoselective aldol reaction between dihydroxyacetone phosphate (DHAP, 1 ) and (2 R ,4 R )-6-benzyloxy-2,4-dimethoxyhexanal ( 8 ) was catalyzed by rabbit muscle aldolase (RAMA) to generate (3 S ,4 R ,5 R ,7 R )-trihydroxyketone 12 , which could be easily transformed to the masked polyhydroxylated compound 15 corresponding to the C-9∼C-16 segment of pentamycin ( 6 ).