Albiziahexoside: a potential source of bioactive saponin from the leaves of Albizzia lebbeck

Albiziahexoside (1), a new hexaglycosylated saponin, was isolated from leaves of Albizzia lebbeck. Saponin 1, which is an analog of cytotoxic albiziatrioside A (2), did not show cytotoxicity. However, 1 is a potential source of 2 and related bioactive saponins for medicinal use because leaves, which can be regenerated after collection, contain 1 in substantial quantity.     

Enantioselective Trichloromethylation of MBH‐Fluorides with Chloroform Based on Silicon‐assisted C−F Activation and Carbanion Exchange Induced by a Ruppert–Prakash Reagent

Enantioselective trichloromethylation of Morita–Baylis–Hillman (MBH)‐type allylic fluorides with chloroform (HCCl₃) under organocatalysis was achieved with high to excellent enantioselectivities. Silicon‐assisted C?F bond activation by a Ruppert–Prakash reagent and direct activation of HCCl₃ by a carbanion exchange process with trifluoromethyl (CF₃) carbanion generated in situ from the Ruppert‐Prakash reagent realized the direct asymmetric trichloromethylation at a stereogenic allylic positon, without any help from transition metal catalysis, and under very mild conditions. Pre‐activation of HCCl₃ was not required. This method was extended to the direct enantioselective introduction of other C?H compounds such as alkyne, arene, indene, and FBSM without any pre‐activation under a metal‐free system.     

Asymmetric Desymmetrization via Metal‐Free C−F Bond Activation: Synthesis of 3,5‐Diaryl‐5‐fluoromethyloxazolidin‐2‐ones with Quaternary Carbon Centers

We disclose the first asymmetric activation of a non‐activated aliphatic C?F bond in which a conceptually new desymmetrization of 1,3‐difluorides by silicon‐induced selective C?F bond scission is a key step. The combination of a cinchona alkaloid based chiral ammonium bifluoride catalyst and N,O‐bis(trimethylsilyl)acetoamide (BSA) as the silicon reagent enabled the efficient catalytic cycle of asymmetric C_sp3?F bond cleavage under mild conditions with high enantioselectivities. The ortho effect of the aryl group at the prostereogenic center is remarkable. This concept was applied for the asymmetric synthesis of promising agrochemical compounds, 3,5‐diaryl‐5‐fluoromethyloxazolidin‐2‐ones bearing a quaternary carbon center.     

Modified guanidines as potential chiral superbases. 2. Preparation Of 1,3-unsubstituted and 1-substituted 2-iminoimidazolidine derivatives and a related guanidine by the 2-chloro-1, 3-dimethylimidazolinium chloride-induced cyclization of thioureas

Simple preparation methods for modified guanidines were explored for new chiral superbases. Thus, (4S,5S)-4,5-diphenyl- and diastereomeric cyclohexane-fused 2-iminoimidazolidines were prepared from (1S,2S)-1,2-diphenylethylenediamine and (1R,2R)- or (1S,2S)-1, 2-diaminocyclohexanes through cyclization of protected thiourea intermediates with 2-chloro-1,3-dimethylimidazolinium chloride (DMC) as a key reaction. In the (4S,5S)-4,5-diphenyl series 1-methyl-2-iminoimidazolidines and 2-diethylaminoimidazoline were also prepared as related guanidines.     

Pilot-scale test on electron beam treatment of municipal solid waste flue gas with spraying slaked-lime slurry

Simultaneous removal of NO_x, SO₂ and HCl in flue gas of a municipal solid waste incinerator was studied by using electron beam irradiation technology. The flue gas around of 1000 Nm³/h was led to a spray-dryer-type reactor from an inlet of ESP of the municipal waste incinerator by spraying slaked-lime slurry with one or more stoichiometic amount of the pollutants, concentrations of HCl (400 ppm) and SO₂ (50 ppm) decreased almost completely, while concentrations of NO_x (100 ppm) were markedly decreased to about 20 ppm by electron beam irradiation with a dose of 10 kGy at 150°C under spraying slaked-time slurry of two stoichiometric amounts. The removal of NO_x was improved by increasing the dose and the amount of spraying slaked-time slurry, and by lowering the irradiation temperature.     

Kinetic resolution of axially chiral 2,2'-dihydroxy-1,1'-biaryls by palladium-catalyzed alcoholysis

Palladium-diamine complexes catalyzed kinetic resolution of axially chiral 2,2'-dihydroxy-1,1'-biaryls by alcoholysis of vinyl ethers. The reaction proceeded with high selectivity for various kinds of biaryls. This process is applicable to not only binaphthols but also biphenols, which have been considered to be difficult for the enantioselective synthesis by known catalytic methods.     

On the antioxidant mechanism of curcumin: classical methods are needed to determine antioxidant mechanism and activity

[reaction: see structure] The antioxidant activity of curcumin (1, 7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) was determined by inhibition of controlled initiation of styrene oxidation. Synthetic nonphenolic curcuminoids exhibited no antioxidant activity; therefore, curcumin is a classical phenolic chain-breaking antioxidant, donating H atoms from the phenolic groups not the CH(2) group as has been suggested (Jovanovic et al. J. Am. Chem. Soc. 1999, 121, 9677). The antioxidant activities of o-methoxyphenols are decreased in hydrogen bond accepting media.     

Structural factors for the formation of propellane-type products in the solvolysis of bicyclic bridgehead compounds

Methanolyses of 2-oxobicyclo[3.3.1]non-1-yl triflate, 3, 3-dimethyl-2-oxobicyclo[3.3.1]non-1-yl triflate, and 2-oxobicyclo[4. 3.1]dec-1-yl mesylate gave the corresponding propellanone in 12%, 20%, or 3.2% yield, respectively, beside substitution or rearranged products under typical conditions. No propellane-type product was obtained in the solvolyses of 1-bromobicyclo[3.3.1]nonane, 2-methylidenebicyclo[3.3.1]non-1-yl heptafluorobutyrate, and 3, 3-dimethyl-2-thioxobicyclo[3.3.1]non-1-yl tosylate. The factors that permit the formation of the propellane-type product from the intermediate bridgehead cations are examined with the aid of theoretical calculations at PM3 and B3LYP/6-31G.     

A powerful,novel, multiplex typing system for six short tandem repeat loci and the allele frequency distributions in two Japanese regional populations

A new multiplex system for six tetranucleotide short tandem repeat (STR) loci was devised based on multicolor dye technology. Six loci (D20S480, D6S2439, D6S1056, D9S1118, D4S2639, and D17S1290), each with high discriminating power (each unbiased estimates of expected heterozygosity, Exp. Hz, > 0.80 in a preliminary test), were selected from more than 100 tetranucleotide STRs included in a commercially available primer set. These loci were also selected so as not to link with general STRs in commercially released kits including the combined DNA index system (CODIS) 13 core STRs. The primers were newly designed in the present study, in which each amplicon size had a range of less than 200 base pairs (bp), in order to genotype from highly degraded template DNA. Using this system, we genotyped 270 Honshu (mainland)-Japanese and 187 Okinawa-Japanese. From these allele frequencies, we performed three tests, a homozygosity test, a likelihood ratio test and an exact test for Hardy-Weinberg equilibrium (HWE), and no significant deviations (p < 0.05) from HWE were observed. We also compared the allele distributions at six STRs between both populations, and they were significantly different (p < 0.05) at three loci (D6S2439, D9S1118 and D4S2639). Furthermore, the Exp. Hz and the power of discrimination (PD) at all loci in the Honshu-Japanese population were higher than 0.80 and 0.93, respectively. These statistical values for discriminating power in the Honshu-Japanese were almost the same as in the Okinawa-Japanese. This novel, multiplex polymerase chain reaction (PCR) amplification and typing system for six STR loci thus promises to be a convenient and informative new DNA profiling system in the forensic field.