New optically active organoantimony (BINASb) and bismuth (BINABi) compounds comprising a 1,1′-binaphthyl core: synthesis and their use in transition metal-catalyzed asymmetric hydrosilylation of ketones

Racemic 2,2′-bis[diarylstibano]-1,1′-binaphthyls [(±)-BINASbs] and 2,2′-bis[di(p-tolyl)bismuthano]-1,1′-binaphthyl [(±)-BINABi], which are the antimony and bismuth congeners of BINAP, have been prepared from 2,2′-dibromo-1,1′-binaphthyl (DBBN) via 2,2′-dilithio-1,1′-binaphthyl intermediate by treatment with the appropriate metal halides [(p-Tol)₂SbBr, Ph₂SbBr and (p-Tol)₂BiCl]. The optical resolution of the (±)-BINASbs could be achieved via the separation of a mixture of the diastereomeric Pd-complexes derived from the reaction of (±)-BINASbs with di-μ-chlorobis{(S)-2-[1-(dimethylamino)-ethyl]phenyl-C¹,N}dipalladium(II). Optically active (R)-BINASb and (R)-BINABi could be also obtained from optically active (R)-DBBN by the same procedure. The enantiopure BINASbs have been shown to be effective chiral ligands for the rhodium-catalyzed asymmetric hydrosilylation of ketones.     

Reactions of 1,2‐dihydro‐4H‐3,1‐benzothiazine‐2,4‐dithiones (trithioisatoic anhydrides) with N‐substituted benzylamines and trialkyl phosphites

Reactions of 1,2‐dihydro‐4H‐3,1‐benzothiazine‐2,4‐dithiones (trithioisatoic anhydrides) 3 with N‐substi‐tuted benzylamines 9 gave 1,2‐dihydroquinazoline‐4‐thiones 10 , o‐thioureidodithiobenzoic acid 11 , o‐aminothiobenzamides 12 , 2‐amino‐3,1‐benzothiazine‐4‐thiones 13 , or quinazoline‐2,4‐dithiones 14 , depending on the kinds of amine and the reaction solvent. On the other hand, reaction of 3 with trialkyl phosphites afforded dialkyl (1,2‐dihydro‐2‐thioxo‐4H‐3,1‐benzothiazin‐4‐yl)phosphonates 18 .     

Insoluble monolayers of irisresorcinol at the air/water interface

Monolayer properties of irisresorcinol [5-(cis-10-heptadecenyl) resorcinol] were measured at the air/water interface. TheA-T isobars of the monolayers at 10 and 15 mN/m gave two-dimensional thermal expansivities of 1.4 × 10^–4/K and 1.3 × 10^–4/K at a temperature span from 7–40 C, respectively. The- A isotherms of the material showed only a little dependence on temperature from 5–35 C and onpH except at highpH, where monolayers expanded by ionization of resorcinol headgroups. Some types of saccharose in the subphase exhibited a characteristic interaction with irisresorcinol in monolayers, and there is a possibility that this material will be used for molecular recognition of some saccharoses.     

Unambiguously confirmed structure of 2-phenacylidene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one and 3-phenacylidene-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one

To determine the structures of two isomeric products, 2-phenacylidene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one (2) and 3-phenacylidene-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one (3) obtained by condensation of 2,3-diaminopyridine (1) with ethyl benzoylpyruvate [1–3], these compounds were hydrolyzed to give 2-methyl-4H-pyrido[2,3-b]pyrazin-3-one (4) and 3-methyl-1H-pyrido[2,3-b]pyrazin-2-one (5) , respectively [4,5]. Both hydrolysates 4 and 5 were hydrogenated to afford 2-methyl-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one (6) and 3-methyl-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one (7) . The latter compound was identical with an unequivocally synthesized compound providing proof for the structures of all these compounds.     

Radical-initiated homopolymerization and copolymerization of ethyl α-hydroxymethylacrylate

Ethyl α-hydroxymethylacrylate (EHMA) was synthesized and homopolymerized in bulk and in solution. The poly(EHMA) is readily soluble in alcohol, acetone, tetrahydrofuran, and methylene chloride at room temperature. Intramolecular lactone formation occurred when poly(EHMA) was heated to 180–230°C. The kinetics of EHMA homopolymerization was investigated in ethyl acetate, using α,α′-azobisisobutylonitrile as an initiator. The rate of polymerization R_p was expressed by R_p = k[AIBN]^0.50[EHMA]^1.4 and the overall activation energy was calculated as 71.9 kJ/mol. Kinetic constants for EHMA polymerization were obtained as follows: k_p/k = 0.17L^0.9mol^?0.9s^?0.5; 2fk_d = 1.5 × 10^?5 s^?1. The relative reactivity ratios of EHMA(M₂) copolymerization with styrene (r₁ = 0.472, r₂ = 0.564) in ethyl acetate were obtained. Applying the Q-e scheme led to Q = 0.84 and e = 0.35 for EHMA.     

Biosorption of chromium(VI) and arsenic(V) onto methylated yeast biomass

Yeast biomass was methylated in a 0.1 M HCl methyl alcohol solution at room temperature and the methylated yeast (MeYE) was applied to the adsorptive separation of Cr(VI) and As(V) anions from aqueous solutions. At near-neutral pH, while Cr(VI) and As(V) anions were scarcely adsorbed onto unmethylated yeast biomass, the amounts adsorbed increased with increasing methylation degree. The amount of Cr(VI) adsorbed onto MeYE was almost constant at pH 4-6 and decreased with increasing pH above pH 6. The amount of As(V) adsorbed onto MeYE was rather lower than that of Cr(VI) and it had a peak at about pH 7. A metal-binding model was used to describe the adsorption characteristics of Cr(VI) and As(V) on MeYE. The results showed that MeYE has two different types of adsorption sites. The saturated amount of Cr(VI) and As(V) adsorbed onto MeYE having methylation degree 0.94 was 0.55 mmol g(-1).     

Integration of gene amplification and capillary gel electrophoresis on a polydimethylsiloxane-glass hybrid microchip

We report on the development of a hybrid polydimethylsiloxane (PDMS)-glass microchip for genetic analysis by functional integration of polymerase chain reaction (PCR) and capillary gel electrophoresis (CGE), and on related temperature control systems for PCR on a PDMS-glass hybrid microchip. The microchip was produced by molding PDMS against a microfabricated master with comparatively simple and inexpensive methods. PCR was successfully carried out on the PDMS-glass hybrid microchip with 500 bp target of lambdaDNA and the amplified gene was subsequently analyzed by CGE on the same PDMS-glass microchip. The chip could be considered as an inexpensive single-use apparatus compared to glass or silicon-made microchips for the same purpose.     

Acid-catalyzed photoreaction of 6-chloro-1,3-dimethyluracil and mesitylene: formation of photocycloadducts and their characterization

In contrast to the previously reported short time required (1 h) for photolysis of 6-chloro-1,3-dimethyluracil (6-CIDMU) and mesitylene, in the presence of TFA, resulting in two major products: 1,3,6,8,10-pentamethylcyclooctapyrimidine derivative (1d), and diazapentacyclo[6.4.0.0(1,3).0(2,5).0(4,8)]dodecane (2c), prolonged irradiation (18h) of this same mixture yields novel pentalenopyrimidine derivatives, including diazapentacyclo[6.4.0.0(1,3).0(2,6).0(4,8)]dodecane (3c).     

Highly efficient recognition of native TpT by artificial ditopic hydrogen-bonding receptors possessing a conformationally well-defined linkage

Synthesis and binding affinity of rationally designed artificial ditopic nucleobase receptors are reported. The ditopic receptors were designed to recognize thymine-thymine dinucleotides by their two hydrogen-bonding moieties, which are connected to conformationally well-defined linkages such as ferrocene and biphenylene. The ditopic receptors exhibited a remarkably strong binding affinity for lipophilic TpT analogue in CDCl(3)/DMSO-d(6) (85:15, v/v). The binding affinity of the ditopic receptors for the dinucleotide was so high that even native TpT was extracted by them into CDCl(3). Detailed comparisons for the recognition abilities of the ditopic receptors were also conducted.     

Calorimetric study of the glassy state XII. Plural glass-transition phenomena of ethanol

Ethanol was found to give a metastable crystalline phase (crystal-II) when the liquid was cooled at a moderate rate. Glassy states of liquid and of newly found crystal-II were obtained in the calorimeter cell by controlling the cooling rate of the liquid. The heat capacities of these phases as well as that of the stable crystal-I were measured by an adiabatic calorimeter in the temperature range between 14 and 300 K. The glass transition temperature T_g, the heat-capacity jump at T_g, and the residual entropy were found to be 97 K, 35.3 J K^?1 mol^?1, and 8.93 J K^?1 mol^?1 for the glassy liquid, and 97 K, 22.8 J K^?1 mol^?1, and 4.24 J K^?1 mol^?1 for the glassy crystal-II, respectively. The values for the residual entropy are referred to the third-law entropy for crystal-I.The heat capacities reported previously for the supercooled liquid by Gibson et al. and by Parks and Kelley agree well with those for the metastable crystal-II. Those of the supercooled liquid connect smoothly with those obtained for the liquid above the melting temperature. Thus, ethanol is found to be another example of a low-molecular-weight compound which shows multiple glass-transition phenomena.