Synthesis of dimethyl gloiosiphone a by way of palladium-catalyzed domino cyclization

The synthesis of a spiro[4.4]nonane skeleton by the palladium-catalyzed domino cyclization of a linear 7-methylene-2,10-undecadienyl acetate is described. The pi-allylpalladium intermediate underwent intramolecular alkene insertion with high intraannular diastereoselectivity, followed by intramolecular Heck-type cyclization, leading to a spiro[4.4]nonane system. Oxidation of the allylic ether moiety and transformation of the vinyl group to an exo-methylene unit provided 3, which is the known synthetic intermediate of dimethyl gloiosiphone A (2).     

The anisotropic low-temperature specific heat of organic superconductor κ-(BEDT-TTF)2CU(NCS)2 in magnetic field

We measured the low-temperature specific heat of the layered organic superconductor κ-(BEDT-TTF)₂Cu(NCS)₂ for the magnetic field directed along and across the conducting plane and found a difference between the two measurements. Our data indicate the existence of a nodeless superconducting state at zero field and low temperature. The field dependence of the specific heat anisotropy consists of two linear branches with the crossover field equal to the upper critical field perpendicular to the conducting plane.     

Oxidation reaction of aliphatic amines and aminoalcohols in aqueous solution induced by argon arc plasma

Argon arc plasma induced a powerful and stepwise oxidation reaction including conversion of methyl group to carboxyl group, oxidative cleavage of carbon-carbon bond, and oxidative deamination. Main active species were considered to be hydroxyl radicals by decomposition of water molecules.     

Synthesis of Unsymmetrical Tetrathiafulvalene Derivatives via Me(3)Al-Promoted Reactions of Organotin Compounds with Esters

Efficient synthetic methods for the construction of a wide variety of unsymmetrical tetrathiafulvalenes (TTFs) via the Me(3)Al-promoted reactions of organotin thiolates or selenolates with esters are described. Reaction of tin thiolates (3a-c and 10) and selenolates (3d, 5, and 7) with esters (11a,b) in the presence of Me(3)Al as a Lewis acid gave dihydrotetrathiafulvalene derivatives (12, 14, 15, and 17-20) and 1,3-dithiane derivatives (13 and 16). In addition, the synthesis of diselenadithiafulvalene derivatives (25-28) could be accomplished by Me(3)Al-mediated reaction of tin thiolate (2a) or selenolates (3d and 5) with esters (22a, 22d, and 24). Furthermore, the application of the Me(3)Al-promoted reaction of tin thiolate (34) with esters (11a-b, 22a-d, and 35a-b) for the synthesis of unsymmetrical TTFs-fused donors enabled us to obtain various TTFs-fused systems (29-33) in short steps.     

Photoinduced electron transfer at the polymer-solution interface. I. Surface property-reactivity relation

Photooxidation of leuco crystal violet(LCV) to the dye(CV⁺) by interfacial sensitization with polymer-bonded pyrenyl groups was studied. Poly(ethylene-g-acrylic acid) was esterified by 1-hydroxymethylpyrene in tetrahydrofuran (THF) (Film 1) or in acetonitrile (Film 2). Film 2 had a more condensed but thinner pyrene-containing surface layer than Film 1. Differences in surface structure were investigated by fluorescence and absorption spectra, as well as by measuring contant angle to water as a function of the total amount of bonded pyrene. Films 1 and 2 behaved differently in the photoreaction, which was interpreted as due to the difference in the affinity of LCV solution to the film surface, hence the diffusion of LCV into the film. The quantum efficiency of CV⁺ formation (?cv⁺) is therefore the function of the thickness of the photoabsorbing layer and the effective reaction volume determined by the depth of LCV diffusion. The role of excimer formation and energy migration among pyrenyl groups was concluded to be of minor importance.     

Integrable hierarchy underlying topological Landau-Ginzburg models of D-type

A universal integrable hierarchy underlying topological Landau-Ginzburg models of D-type is presented. Like the dispersionless Toda hierarchy, the new hierarchy has two distinct (positive and negative) sets of flows. Special solutions corresponding to topological Landau-Ginzburg models of D-type are characterized by a Riemann-Hilbert problem, which can be converted into a generalized hodograph transformation. This construction gives an embedding of the finite-dimensional small phase space of these models into the full space of flows of this hierarchy. One of flat coordinates in the small phase space turns out to be identical to the first negative time variable of the hierarchy, whereas the others belong to the positive flows.     

Stereoselective Synthesis of cis‐β‐Methyl‐ and Phenyl‐Substituted Alkenylboronates by Platinum‐Catalyzed Dehydrogenative Borylation

Changing places : Intramolecular B(pin)/H exchange took place in the presence of a platinum–phosphane catalyst, giving synthetically useful cis‐β‐methyl‐substituted alkenylboronates stereoselectively (see scheme; B(pin)=4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl).

     

Selecting effective siRNA target sequences by using Bayes’ theorem

Short interfering RNA (siRNA) has been widely used for studying gene functions in mammalian cells but varies markedly in its gene silencing efficacy. Although many design rules/guidelines for effective siRNAs based on various criteria have been reported recently, there are few consistencies among them. This makes it difficult to select effective siRNA sequences in mammalian genes. Another shortcoming of most previously reported methods is that they cannot estimate the probability that a candidate sequence will silence the target gene. The analytical prediction method proposed in the present study uses Bayes’ theorem to select effective siRNA target sequences from many possible candidate sequences. It is quite different from the previous score-based siRNA design techniques and can predict the probability that a candidate siRNA sequence will be effective. The results of evaluating it by applying it to recently reported effective and ineffective siRNA sequences for various genes indicate that it would be useful for many other genes. It should therefore be useful for selecting siRNA sequences effective for mammalian genes.