We describe the design of an efficient waterless condenser for use in chemical synthesis, which exists in two different sizes. This laboratory equipment displays performances comparable to those of conventional water-jacketed glass condensers across a broad range of organic solvents. It is most effective when fitted with a Teflon cap containing a safety valve. The condenser with the smallest cross-section is particularly suitable for reactions using water as a solvent, despite its lower vapor density than air.

Enterovirus A71 (EV-A71) causes hand, foot, and mouth disease outbreaks with neurological complications and deaths. We previously isolated an EV-A71 variant in the stool, cerebrospinal fluid, and blood of an immunocompromised patient who had a leucine-to-arginine substitution on the VP1 capsid protein, resulting in increased heparin sulfate binding. We show here that this mutation increases the virus's pathogenicity in orally infected mice with depleted B cells, which mimics the patient's immune status, and increases susceptibility to neutralizing antibodies. However, a double mutant with even greater heparin sulfate affinity is not pathogenic, suggesting that increased heparin sulfate affinity may trap virions in peripheral tissues and reduce neurovirulence. This research sheds light on the increased pathogenicity of variant with heparin sulfate (HS)-binding ability in individuals with decreased B cell immunity.

Abstract While the integration of supramolecular principles in catalysis attracts increasing attention, a direct comparative assessment of the resulting systems catalysts to work out distinct characteristics is often difficult. Herein is reported how the broad responsiveness of ether cyclizations to diverse inputs promises to fill this gap. Cyclizations in the confined, π‐basic and Brønsted acidic interior of supramolecular capsules, for instance, are found to excel with speed (exceeding general Brønsted acid and hydrogen‐bonding catalysts by far) and selective violations of the Baldwin rules (as extreme as the so far unique pnictogen‐bonding catalysts). The complementary cyclization on π‐acidic aromatic surfaces remains unique with regard to autocatalysis, which is shown to be chemo‐ and diastereoselective with regard to product‐like co‐catalysts but, so far, not enantioselective.

The development of a user-friendly reusable laboratory equipment for the delivery of sensitive reagents and catalysts is described. The tightness of these Teflon Magnetic Stirring Capsules (TMSC) is ensured by the magnetic force and release of the reagent inside the solution is triggered by adjusting the stirring rate so that the centrifuge force exceeds the magnetic force. They can be loaded with several chemicals at the same time and do operate across a broad range of temperatures. The inertness of Teflon facilitates reaction purification.

Enantioenriched Al-, Mg-, and Zn-enolates undergo electrophilic trapping by nitroolefins and vinylsulfones to afford 1,4-diketones and 2-(bis(phenylsulfonyl)ethyl)ketones in good yield and excellent diastereoselectivity. A one-pot preparation of indenes and enantiopure syntheses of tetrahydrobenzofurans, tetrahydrobenzopyrroles, and azulenes are disclosed. A site-selective two-step sequence of three conjugate additions is also demonstrated.

AbstractDiketones and phenylsulfonylketones can be obtained via the title reaction by using the corresponding enolates which undergo electrophilic trapping by nitroolefins or vinylsulfones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A biaryl-based monophosphoroamidite L1–L4a–f and aminophosphine L5–L7a–f ligand library was screened in the Rh-catalyzed asymmetric hydroformylation of several vinylarenes and heterocyclic olefins. Our results indicate that the selectivity is strongly dependent on the ligand parameters and on the substrate type. Enantioselectivities (up to 46%) were moderate in the hydroformylation of several vinylarenes S1–S5 and promising (up to 58%) for the more challenging heterocyclic olefins S6–S9.

A series of easily prepared bulky P*-chiral diamidophosphites based on (2R,5S)-3-phenyl-1,3-diaza-2-phosphabicyclo[3.3. 0]octane and (2R,5S)-3-(p-bromophenyl)-1,3-diaza-2-phosphabicyclo [3.3.0]octane backbones have been designed and developed. Ligands of this type exhibited high enantioselectivities in Pd-catalysed allylic substitution reactions of (E)-1,3-diphenylallyl acetate with NaSO(2)pTol (up to 87% ee), CH2(CO2Me)(2) (up to 92 % ee), (C3H7)(2)NH (up to 93 % ee) and (CH2)(4)NH (up to 99 % eel. These novel stereoselectors have also been successfully employed in Rh-catalysed asymmetric hydrogenations of dimethyl itaconate (up to 76 % ee), methyl (Z)-2-acetamido-3-phenylacrylate (up to 73% ee) and methyl 2-acetamidoacrylate (up to 98 % ee). Cu-catalysed conjugate addition of diethylzinc to cyclohexenone leads to a maximum of 70%) ee with quantitative conversion. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A modular sugar-based phosphoroamidite L1–L5a–g and phosphite L6–L9a–g ligand library was tested in the asymmetric Cu-catalyzed 1,4-conjugate addition reactions of β-substituted (cyclic and linear) and β,β′-disubstituted (cyclic) enones. The selectivity depended strongly on the configuration of carbon atom C-3, the size of the sugar backbone ring, the flexibility of the ligand backbone, the substituents and configurations in the biaryl phosphoroamidite moieties a–g, the type of functional group attached to the ligand backbone and the substrate structure. Therefore, by carefully selecting the ligand parameters, enantioselectivities of up to 60% for cyclic substrates and 72% for linear ones were achieved.

A sugar-based phosphite–phosphoroamidite and diphosphoroamidite ligand library L1–L5a–g was tested in the asymmetric Cu-catalyzed 1,4-conjugate addition reactions of β-substituted and β,β′-disubstituted enones. Our results indicated that the selectivity was strongly dependent on the ligand parameters and on the substrate structure. Moderate-to-good enantioselectivities (ees up to 84%) were obtained in the 1,4-addition of several types of β-substituted cyclic and linear substrates. Of particular note is the high enantioselectivity (ees up to 90%) obtained for the more challenging β,β′-disubstituted 3-methyl-cyclohexenone.

The Alexakis group describes a new class of monodentate phosphorous ligands termed SimplePhos. These modular ligands are based on bisarylaminophosphines instead of the more common phosphoramidite compounds. These ligands achieved similar or better enantio­selectivities than their phosphoramidite counterparts in the copper-catalyzed conjugate addition reaction to cyclohexenones, desymmetrization of polycyclic hydrazines as well as allylic alkylation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Phosphoramidites based on BINOL readily react with trimethylaluminum in "noncoordinating" solvents, leading to the corresponding aminophosphine which is the real ligand in copper-catalyzed asymmetric transformations. This artifact explains the experimental differences in the asymmetric ring opening of meso bicyclic hydrazines using dialkylzinc or trialkylaluminum reagents as nucleophiles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The synthesis and characterization of seven new phosphoramidite ligands are described, as well as their use in copper-catalyzed 1,4-addition of diethylzine to a wide range of substrates. Enantioselectivities of up to >99.5% are obtained. (C) 2004 Elsevier Ltd. All rights reserved.

[structure: see text] Full conversion and enantioselectivities up to 83% have been obtained in the conjugate addition reactions of diethyl zinc to Michael acceptors catalyzed by well-defined (chiral) copper(I) aminoarenethiolates. Interesting differences between organozinc or Grignard reagents have been found: for cyclic enones R(2)Zn reagents afford better results, whereas earlier work showed that RMgX reagents react more selectively with acyclic enones.

Phosphoramidite ligands, based on ortho-substituted biphenols and a chiral amine, induce high enantioselectivities (ee's up to 99%) in the copper-catalyzed conjugate addition of dialkylzinc reagents to a variety of Michael acceptors. Particularly, the best reported ee's were obtained for acyclic nitroolefins.

A novel one-pot reductive amination of ketones using the combination Ti(OiPr)4/H2/Pd–C is reported. This practical procedure does not require any solvent and affords C2-symmetrical secondary amines in high yields and excellent diastereoselectivities.