Complete bioconversion of hemicellulosic sugars from agricultural residues into lactic acid by Lactobacillus pentosus

On the basis of previous knowledge, different agroindustrial wastes were submitted to dilute-acid hydrolysis with H2SO4 to obtain hemicellulosic sugars and then employed for lactic acid production by Lactobacillus pentosus. Toxic compounds released from lignin did not affect lactic acid fermentation when hydrolysates from trimming vine shoots, barley bran husks, or corncobs were employed as carbon source, and complete bioconversion of hemicellulosic sugars was achieved. Nevertheless, Eucalyptus globulus hydrolysates had to be submitted to a detoxification process with activated charcoal. Maximum lactic acid concentration (33 g/L) was reached employing barley bran hydrolysates, whereas corncobs, trimming vine shoots, and detoxified E. globulus hydrolysates yielded 26, 24, and 14.5 g/L of lactic acid, respectively. The maximum product yield from pentoses (0.76 g/g) was achieved using hydrolysates from trimming vine shoots, followed by hydrolysates from detoxified E. globulus (0.70 g/g), barley bran (0.57 g/g), and corncob (0.53 g/g). These results confirm that L. pentosus can be employed to ferment hemicellulosic sugars (mainly xylose, glucose, and arabinose) from acid hydrolysates of most agricultural residues without appreciable substrate inhibition.     

On-water chemistry: copper-catalyzed straightforward synthesis of benzo[b]furan derivatives in neat water

[reaction: see text] A more sustainable protocol leading to 2-alkyl- or 2-aryl-substituted benzo[b]furans is reported, involving a copper-TMEDA complex which catalyzes the transformation of readily available ketone derivatives into the corresponding benzofurans in good to excellent yields. The reaction is accomplished using water as the solvent without organic cosolvents, and one example of catalyst reutilization is also presented.     

Synthesis and receptor binding evaluation of clavizepine analogues with no ring D substituents

Assembly of the azepine ring of xantheno[9,1-cd]azepines by electrophilic cyclization of sulfonamide acetals provides access to clavizepine analogues in the form of 2,12b-dihydro- or 4-hydroxy-2,3,4,12b-tetrahydro-1H-xantheno[9,1-cd]azepines, in the latter case producing the trans derivative stereoselectively. Binding assays for clavizepine and analogues at adrenergic, dopaminergic, and serotonergic receptors are reported.     

A metal-free approach to the synthesis of indoline derivatives by a phenyliodine(III) bis(trifluoroacetate)-mediated amidohydroxylation reaction

A novel approach to the synthesis of indoline derivatives is presented. The key cyclization step features the phenyliodine(III) bis(trifluoroacetate)- (PIFA-) mediated formation of a N-acylnitrenium ion and its succeeding intramolecular trapping by the olefin fragment. In addition, difunctionalization of the alkene moiety is achieved since the in situ generation of an additional hydroxy group at the terminal position of the original double bond accompanies the intramolecular C-N bond formation.     

2‐Arylimino(diferrocenyl)‐ and (di‐p‐anisyl)dihydropyrimidines: Novel Synthesis,Structures, and Electrochemistry

2,3‐Differocenyl‐ and 2,3‐dianisyl‐1‐methylsulfanylcyclopropenilium iodides react with 1,3‐diphenyl‐ and 1,3‐di‐o‐tolylguanidine to give 1‐aryl‐2‐arylimino‐5,6‐ ( 5a , 5b ) and ‐4,5‐diferrocenyl‐1,2‐dihydropyrimidines ( 6a , 6b ) (～ 2:1) and, respectively, 5,6‐ and 4,5‐dianisyl‐3‐phenyl‐2‐phenylimino‐1,2‐dihydropyrimidines (～ 2:1). Their structures were established based on the spectroscopic data and X‐ray diffraction analysis of 5,6‐diferrocenyl‐1‐(o‐tolyl)‐2‐(o‐tolyl)imino‐ and 4,5‐diferrocenyl‐1‐phenyl‐2‐phenylimino‐1,2‐dihydropyrimidines ( 5b and 6a , respectively). Electrochemical behavior of compounds 5b, 6b, and 5a+6a were investigated using experiments of cyclic voltammetry and chronoamperometry. For all the compounds, two electrochemical processes ( I , II ), attributed to the oxidations of the ferrocenes moieties were observed. The values of ΔE^0′ ( II‐I ) and comproportionation constant K_com are also reported. Additionally, an electrochemical oxidation with a fast coupled chemical reaction related to the pyrimide ring was also detected.     

Separation of enantiomers of norephedrine by capillary electrophoresis using cyclodextrins as chiral selectors: comparative CE and NMR studies

In this study, the enantiomer migration order (EMO) of norephedrine (NEP) in the presence of various CDs was investigated by CE. NMR and CE techniques were used to analyze the mechanism of the chiral recognition between NEP enantiomers and four CDs, i.e., native α-CD, β-CD, heptakis(2,3-di-O-acetyl-6-O-sulfo)-β-CD (HDAS-β-CD), and heptakis(2,3-di-O-methyl-6-O-sulfo)-β-CD (HDMS-β-CD). EMO was reversed in the presence of α-CD and β-CD, although only minor differences in the structures of the complexes formed between NEP and these CDs could be derived from rotating frame nuclear Overhauser experiments (ROESY). The complexes between the enantiomers of NEP and the sulfated CDs, HDMS-β-CD, and HDAS-β-CD, were substantially different. However, EMO of NEP was identical in the presence of these CDs. HDAS-β-CD proved to be the most suitable chiral selector for the CE enantioseparation of NEP.     

Stereocontrolled synthesis of (S)-9-cis-4-oxo-13,14-dihydroretinoic acid

(S)-9-cis-4-Oxo-13,14-dihydroretinoic acid (S)-1, a new major endogenous vitamin A metabolite that activates retinoic acid receptor signaling both in vitro and in vivo, has been synthesized stereoselectively by Horner–Wadsworth–Emmons condensation and Stille cross-coupling as bond forming reactions.     

Semivalues: weighting coefficients and allocations on unanimity games

Each semivalue, as a solution concept defined on cooperative games with a finite set of players, is univocally determined by weighting coefficients that apply to players’ marginal contributions. Taking into account that a semivalue induces semivalues on lower cardinalities, we prove that its weighting coefficients can be reconstructed from the last weighting coefficients of its induced semivalues. Moreover, we provide the conditions of a sequence of numbers in order to be the family of the last coefficients of any induced semivalues. As a consequence of this fact, we give two characterizations of each semivalue defined on cooperative games with a finite set of players: one, among all semivalues; another, among all solution concepts on cooperative games.