bluuebunny/crossref_metadata_2025 huggingface dataset:
New Recoverable Poly(ethylene glycol)‐Supported C1‐Diamino‐oligothiophene Ligands for Palladium‐Promoted Asymmetric Allylic Alkylation (AAA) Reactions
Authors: Bandini Marco , Benaglia Maurizio , Quinto Tommaso , Tommasi Simona , Umani‐Ronchi Achille
Published: August 2006

A new class of chiral C1‐symmetrical diamino‐oligothiophene ligands easy‐grafted on a soluble polymeric support (MeOPEG5000) is described. The diamines were found to be effective promoting agents for the [Pd(0)]‐catalysed asymmetric allylic alkylation (AAA) of dimethyl malonate in high yields and excellent enantioselectivity (ee up to 99 %). The supported chiral ligand was readily recovered by precipitation and filtration was recycled up to three times without an appreciable loss in activity. The recycle of the organometallic catalytic system was also investigated.
Electroreductive Palladium‐Catalysed Ullmann Reactions in Ionic Liquids: Scope and Mechanism
Authors: Pachón Laura Durán , Elsevier Cornelis J. , Rothenberg Gadi
Published: August 2006

A room‐temperature catalytic alternative to the Ullmann reaction is presented, based on electroreductive homocoupling of haloarenes catalysed by palladium nanoparticles. The particles are generated in situ in an electrochemical cell, and electrons are used to close the catalytic cycle and provide the motivating force for the reaction. This system gives good yields using iodo‐ and bromoarenes, and requires only electric current and water as reagents. Using an ionic liquid solvent combines the advantages of excellent conductivity and cluster stabilising. The solvent is reusable at least five times. Kinetic experiments at different electrode potentials show that the two‐electron oxidation of water closes the catalytic cycle by regenerating the Pd(0). A mechanism involving radical anion formation is proposed. The advantages and limitations of this new system for carbon‐carbon homocoupling and cross‐coupling are discussed.
In situ Synthesis of Gold Nanoparticles inside the Pores of MCM‐48 in Supercritical Carbon Dioxide and its Catalytic Application
Authors: Chatterjee M. , Ikushima Y. , Hakuta Y. , Kawanami H.
Published: August 2006

Gold nanoparticles are deposited into the channels of MCM‐48 through a simple H2‐assisted reduction of HAuCl4 (aqueous solution) in supercritical carbon dioxide medium at 70 °C within 2–4 h. The nanoparticles were characterized by powder X‐ray diffraction (PXRD), N2 adsorption‐desorption, transmission electron microscopy (TEM), and UV‐Vis spectroscopy. The particle size of the synthesized material is tunable with the pressure (density) of the supercritical carbon dioxide medium. At the fixed temperature (70 °C) and hydrogen pressure [P(H2)=2 MPa], the Au particle size varies from ca. 25 nm to ca. 2 nm with the change in CO2 pressure from 7 MPa to 17 MPa. At the low solvent density conditions, larger particles of ∼25 nm were obtained. On the contrary, a high solvent density of CO2 slows down particle aggregation, resulting in the small particle size within the range of 2–5 nm. This change in particle size with CO2 pressure and the interaction of the particles with the silica support were correlated well with long‐range van der Waals interactions and consequently the Hamaker constant for the gold nanoparticle‐CO2 (A131) and silica‐gold core‐CO2 (A132), respectively. Supercritical carbon dioxide alone can provide a unique environment for stabilizing gold nanoparticles in the channels of the cubic mesoporous MCM‐48 support and exquisite control of the particle size without perturbing the support structure. The synthesized material is highly stable, recyclable and no metal nanoparticle leaching was observed. The selective hydrogenation of crotonaldehyde with the synthesized material provides convincing evidence that the particles are inside the pores and available to the reactant molecules.
Syntheses and Properties of Fluorous Quaternary Phosphonium Salts that Bear Four Ponytails; New Candidates for Phase Transfer Catalysts and Ionic Liquids
Authors: Emnet Charlotte , Weber Kathleen M. , Vidal José A. , Consorti Crestina S. , Stuart Alison M. , Gladysz J. A.
Published: August 2006

The fluorous tertiary phosphine [Rf6(CH2)2]3P [Rfn=CF3(CF2)n−1] and excess PhCH2Br, CH3(CH2)3OSO2CF3, or Rf6(CH2)2OSO2CF3 react (CF3C6H5, 45–110 °C) to give the phosphonium salts (PhCH2)[Rf6(CH2)2]3P+ Br− (2, 71 %), [CH3(CH2)3][Rf6(CH2)2]3P+ CF3SO3− (3, 65 %), or [Rf6(CH2)2]4P+ CF3SO3− (4, 83 %). The phosphines [Rf6(CH2)2]2[Rf8(CH2)2]P and [Rf8(CH2)2]3P are similarly elaborated with Rf6(CH2)2I, Rf8(CH2)2I, or Rf8(CH2)2Br (DMF, 115 °C) to [Rf8(CH2)2]4‐x[Rf6(CH2)2]xP+ I− (x=3, 7; 2, 8; 1, 9; 0, 10) or [Rf8(CH2)2]4P+ Br− (80–60 %). The salts exhibit melting points between 110 °C and 43 °C, with lower values favored by less symmetrical cations, Rf6 segments, and triflate and bromide anions. Solubilities decrease in the solvent sequence CF3C6F5 (all salts at least moderately soluble, room temperature)>acetone>THF>CF3C6H5>CF3C6F11>CH3C6H5, Et2O, CH2Cl2, hexane (all salts insoluble at elevated temperatures); some appreciably increase upon heating. Partition coefficients are very biased towards fluorous phases (>93:<7). The salts can be quite efficient at extracting picrate from water into CF3C6F5 (97–86 % for 2, 4, 9, 10) or CF3C6H5 (85–66 % for 2‐4), demonstrating their potential for phase transfer catalysis. A CF3C6F5 solution of Rf8(CH2)3I and aqueous NaCl react at 100 °C in the presence (but not the absence) of 9 to give Rf8(CH2)3Cl.
Immobilized Hydroxynitrile Lyases for Enantioselective Synthesis of Cyanohydrins: Sol‐Gels and Cross‐Linked Enzyme Aggregates
Authors: Cabirol Fabien L. , Hanefeld Ulf , Sheldon Roger A.
Published: August 2006

The hydroxynitrile lyases (HNLs) from Prunus amygdalus (PaHNL), Manihot esculenta (MeHNL), and Hevea brasiliensis (HbHNL) were successfully immobilized in sol‐gels. The cross‐linked enzyme aggregate (CLEA) of HbHNL was also prepared. These immobilized enzymes and the commercial PaHNL‐ and MeHNL‐CLEAs were employed for the enantioselective synthesis of cyanohydrins. The sol‐gels were highly efficient at low catalyst loading and particularly stable towards the organic solvent (diisopropyl ether) and substrate/product deactivation. The stabilization effect was inconsistent for CLEAs of different HNLs and significant deactivation of PaHNL‐ and HbHNL‐CLEAs in diisopropyl ether was observed. In contrast commercial MeHNL‐CLEA proved to be a remarkably robust and efficient biocatalyst in diisopropyl ether.
Supported Fluorous Phase Catalysis on PTFE, Fluoroalkylated Micro‐ and Meso‐porous Silica
Authors: Hope Eric G. , Sherrington James , Stuart Alison M.
Published: August 2006

New perfluoroalkylated micro‐ and mesoporous silica, along with powdered Teflon, have been evaluated as solid supports for supported fluorous phase catalysis in a model reaction; the hydrogenation of styrene using a fluorous analogue of Wilkinson’s catalyst. Each support material showed catalytic activity and catalyst‐leaching behaviour related to its surface area and was consistent with supported liquid phase catalysis. However, catalyst decomposition on the silica supports resulted in substantial reductions in activity on catalyst recycle. In contrast, although activity and leaching levels on PTFE were poorer, the supported catalyst was recycled successfully.
Methoxycarbonylation of Iodobenzene in Ionic Liquids. A Case of Inhibiting Effect of Imidazolium Halides
Authors: Zawartka W. , Trzeciak A. M. , Ziółkowski J. J. , Lis T. , Ciunik Z. , Pernak J.
Published: August 2006

The palladium(II) complexes, PdCl2(cod) (1), PdCl2[P(OPh)3]2 (2), [bmim]2[PdCl4] (3), and [bmpy]2[PdCl4] (4) (bmim=1‐butyl‐3‐methylimidazolium cation, bmpy=1‐butyl‐4‐methylpyridinium cation), were found to be active catalysts for the methoxycarbonylation of iodobenzene in ionic liquid (IL) media. The best results were obtained in pyridinium salts, [bmpy]X (X=Cl, Br, BF4, PF6) (76–100 % yield). In methoxycarbonylation reactions carried out in imidazolium salts, [bmim]BF4 and [bmim]PF6, the yield of benzoic acid methyl ester was slightly lower (50–78 % yield), whereas in [bmim]X (X=Cl, Br) the reaction was totally retarded. The inhibiting effect was not observed when a Me group was present at C‐2 (instead of a proton) on the imidazole ring. A palladium‐carbene complex, Pd(bmimy)2Br2 (5), obtained in the reaction of a palladium catalyst precursor with [bmim]Cl, presented much lower activity than precursors 1–4. Its formation may explain the observed inhibition of methoxycarbonylation in a [bmim]Cl medium.
Generation of Self‐Supported Noyori‐Type Catalysts Using Achiral Bridged‐BIPHEP for Heterogeneous Asymmetric Hydrogenation of Ketones
Authors: Liang Yuxue , Wang Zheng , Ding Kuiling
Published: August 2006

The programmed assembly strategy has been applied to the generation of self‐supported Noyori‐type catalysts for asymmetric hydrogenation of ketones by spontaneous hetero‐coordination of an achiral bridged diphosphine and chiral bridged diamine ligands with RuII metal ions. The immobilized catalyst demonstrates good enantioselectivity and activity in the heterogeneous catalysis of the hydrogenation of aromatic ketones and can be recovered and recycled for 4 times without obvious loss of selectivity and activity.
Liquid/Liquid Biphasic Recovery/Reuse of Soluble Polymer‐ Supported Catalysts
Authors: Bergbreiter David E. , Sung Shayna D.
Published: August 2006

Liquid/liquid separations using gravity and two phases of different density are a practical and viable way to recover, separate and reuse soluble polymer‐supported catalysts. Such separations are facilitated by using polymers that have phase‐selective solubility under biphasic conditions. Such polymers can be designed to be soluble either in a non‐polar or a polar phase. Since catalyst and ligand loading can be at a low mole percent level on the polymer, the polymer’s intrinsic solubility can be maintained with a variety of ligands and catalysts making such separation strategies general. Catalysis with such soluble polymer‐supported species can either be carried out under biphasic or monophasic conditions. In the former case, aqueous/organic, fluorous/organic or other biphasic regimes can be used. In the later case, thermomorphic or latent biphasic conditions can be employed. In either case, catalyst separation and recovery can be accomplished simply without using significant quantities of additional solvent.
A Combinatorial Approach to Heterogeneous Asymmetric Aquacatalysis with Amphiphilic Polymer‐Supported Chiral Phosphine‐Palladium Complexes
Authors: Kobayashi Yukinari , Tanaka Daiki , Danjo Hiroshi , Uozumi Yasuhiro
Published: August 2006

A library of amphiphlic polystyrene‐poly(ethylene glycol) (PS‐PEG) resin‐supported chiral phosphine ligands was prepared by the split method using porous miniature reactors. A polymeric (R)‐2‐(diphenylphosphino)binaphthyl (MOP) ligand anchored onto the PS‐PEG resin by an (S)‐alanine tether unit was identified through the library‐based screening to be an effective chiral ligand for the asymmetric palladium‐catalyzed π‐allylic substitution under heterogeneous aqueous conditions.
Hydroformylation of 1‐Octene in Supercritical Carbon Dioxide and Organic Solvents using Trifluoromethyl‐Substituted Triphenylphosphine Ligands
Authors: Koeken Ard C. J. , van Vliet Michiel C. A. , van den Broeke Leo J. P. , Deelman Berth‐Jan , Keurentjes Jos T. F.
Published: August 2006

Two different in situ prepared catalysts generated from Rh(CO)2acac and trifluoromethyl‐substituted triphenylphosphine ligands have been evaluated for their activity and selectivity in the hydroformylation of 1‐octene. The solvents used were supercritical carbon dioxide, hexane, toluene, and perfluoromethylcyclohexane. The highest value for the turnover frequency, 9820 mol1‐octene molRh−1 h−1, has been obtained in supercritical carbon dioxide using ligand I, P[C6H3‐3,5‐(CF3)2]3. For both supercritical carbon dioxide and hexane employing ligand II, P(C6H4‐3‐CF3)3, a selectivity towards the linear aldehyde product, nonanal, and an n:iso ratio of 79.3 % and 4.6–4.8 have been obtained, respectively. These values are significantly higher than those obtained with triphenylphosphine as ligand (nonanal: 74–76 %, n:iso: 3.1–3.3). An increase in trifluoromethyl substitution on the triphenyl ligand results in an increase in the 1‐octene conversion rate, an increase in the n:iso ratio and a decrease in the overall selectivity towards aldehydes. In terms of turn‐over frequency and selectivity the three ligands give comparable results in supercritical carbon dioxide and hexane. This leads to the conclusion that the properties of supercritical carbon dioxide as a solvent for hydroformylation can be better compared with those of hexane rather than with those of toluene.
Palladium‐Catalysed Direct Regioselective Synthesis of Cyclic Ketals from Electron‐Rich Olefins and Aryl Bromides in Ionic Liquids
Authors: Hyder Zeynab , Mo Jun , Xiao Jianliang
Published: August 2006

The Heck reaction comprises one of the most important carbon‐carbon coupling reactions in organic synthesis. The popularity of the reaction is attributable to the broad availability of aryl halides and to the tolerance of the reaction for a wide variety of functional groups. Reported herein is a direct method for the highly regioselective preparation of 5‐membered and 7‐membered cyclic ketals in respectable to good yields from aryl bromides (1a–k) and electron‐rich olefins (2a and b). The reaction is performed with palladium catalysis using ionic liquid as solvent with no need for any halide scavengers, providing an alternative to the use of aryl triflates. The ionic liquid is found to direct the reaction pathway towards exclusive α‐arylation via a cationic route.
The Immobilization of Rhodium‐4‐(diphenylphosphino)‐2‐ (diphenylphosphinomethyl)‐pyrrolidine (Rh‐PPM) Complexes: A Systematic Study
Authors: Pugin Benoît , Blaser Hans‐Ulrich
Published: August 2006

A modular toolbox for the immobilization of homogeneous catalysts to various supports is described. It consists of functionalized chiral diphosphines and three different linkers based on isocyanate chemistry and it is used to attach the 4‐(diphenylphosphino)‐2‐(diphenylphosphinomethyl)‐pyrrolidine (PPM) ligand to a large variety of soluble, swellable and non‐swellable solid organic polymers and to silica gels. As model reaction the hydrogenation of acetamidocinnamic acid derivatives, catalyzed with high enantioselectivity was chosen. Besides information on the usefulness of a particular type of support for synthetic applications, the experiments were also designed to address the question how parameters such as solubility, swellability, cage or pore size and solvent affect the rate and enantioselectivity of an immobilized catalyst. Rhodium complexes of ligands attached to soluble polymers and inorganic supports achieved ees up to 95 % and turnover frequencies between 700 and 1400 h−1, very close to the values of the homogeneous Rh catalyst (ee 95 %, TOF 1320 h−1). Insoluble or strongly cross‐linked organic polymers led to catalysts with lower enantioselectivity and activity. PPM ligands attached to water soluble dendrimer fragments allowed hydrogenation in water solution with ees up to 94 %, albeit with much lower activity compared to reactions in methanol with the homogeneous catalyst.
Asymmetric Catalytic Synthesis of Organic Compounds using Metal Complexes in Supercritical Fluids
Authors: Cole‐Hamilton David J.
Published: August 2006

The applications of metal‐based catalysts for the asymmetric synthesis of organic compounds in supercritical fluids are reviewed. Much of the work discussed concerns hydrogenation and hydroformylation of alkenes, but dihydoxylation and cyclopropanation reactions of alkenes are discussed as are asymmetric Diels–Alder reactions and aldol condensations. Supercritical fluids remove the need for harmful volatile organic solvents, but their use in separating the products from the catalyst by pressure swings or multiphasic systems is also described.
Continuous Asymmetric Hydrogenation in Supercritical Carbon Dioxide using an Immobilised Homogeneous Catalyst
Authors: Stephenson Phil , Kondor Betti , Licence Peter , Scovell Katherine , Ross Stephen K. , Poliakoff Martyn
Published: August 2006

Continuous flow supercritical carbon dioxide (scCO2) has previously been shown (P. Stephenson, P. Licence, S. K. Ross, M. Poliakoff, Green Chem. 2004, 6, 521) to be a viable medium for conducting continuous asymmetric hydrogenation when it is combined with an appropriate enantioselective catalyst. Here we examine the use of a composite catalyst immobilisation system modified with several different types of asymmetric bisphosphine ligands in continuous flow scCO2. In particular, proprietary ligands from Solvias AG were found to be the most successful, with Josiphos 001 improving the enantiomeric excess (ee) to>80 % in the asymmetric hydrogenation of dimethyl itaconate (DMIT); this ee is higher than that reported for the batch hydrogenation of DMIT using a homogeneous catalyst fully dissolved in scCO2 (S. Lange, A. Brinkmann, P. Trautner, K. Woelk, J. Bargon, W. Leitner, Chirality 2000, 12, 450).
Purification of Fluorous Mitsunobu Reactions by Liquid‐Liquid Extraction
Authors: Curran Dennis P. , Bajpai Reena , Sanger Elizabeth
Published: August 2006

Solvent tuning and partition coefficient measurements have identified suitable reagent and solvent combinations for the purification of fluorous Mitsunobu reaction products. The crude reaction mixtures are partitioned between 2/1 HFE‐7100/FC‐72 and DMF/10 % water to provide reagent (fluorous) and product (organic) fractions.
Silica‐Bound Homogenous Catalysts as Recoverable and Reusable Catalysts in Organic Synthesis
Authors: Corma Avelino , Garcia Hermenegildo
Published: August 2006

Very frequently the most costly components in a chemical reaction are not the starting materials or the reaction products, but the catalyst. In addition to the advantages from the economic point of view, recovery and reuse of the catalyst is equally important in order to avoid wastes, so improving the greenness of the process. There is a current tendency to transform homogeneous into heterogeneous catalysis, that will even be accelerated in the near future. Starting from a successful homogeneous catalyst, one general methodology allowing its recovery and reuse is to immobilize a suitable derivative of the active catalyst on an insoluble solid support. When the catalyst does not deactivate and is sufficiently stable under the reaction conditions, the ultimate immobilization methodology is to attach covalently the catalytically active species to the support. In this contribution, after introducing some general principles describing the fundamentals of the covalent anchoring, the emphasis is placed more on giving an overview of the most important types of covalently anchored catalysts, including Brönsted and Lewis acids, covalently anchored bases and hydrogenation complexes. Hot topics such as silica‐bound organocatalysts and the application of periodic mesoporous organosilicas as heterogeneous catalysts is also covered.
Aspects of Immobilisation of Catalysts on Polymeric Supports
Authors: Dioos Bart M. L. , Vankelecom Ivo F. J. , Jacobs Pierre A.
Published: August 2006

In this review the authors intend to make a tutorial review on catalyst immobilisation from the viewpoint of the catalyst designer, emphasizing the use of promising concepts in this area, rather than trying to be exhaustive. The following topics are covered:
Numerical modeling of highly swirling flows in a through‐flow cylindrical hydrocyclone
Authors: Ko Jordan , Zahrai Said , Macchion Olivier , Vomhoff Hannes
Published: August 2006

This article aims to identify the most appropriate numerical methodology for simulating hydrocyclone flows with high swirl numbers. The numerical results are validated against the tangential velocity measurements from a cylindrical hydrocyclone with a swirl number of 8.1, which is twice the typical swirl magnitude of industrial hydrocyclones. The linear and quadratic formulations of the Reynolds stress transport (RST) model are used to simulate the anisotropic swirling turbulent flow three‐dimensionally in the commercial software package Fluent™. The tangential velocity profiles predicted by the quadratic RST model are in good agreement with experimental data. They also show Rankine vortex patterns over the entire flow domain. In contrast, the linear RST model fails to predict this important swirl flow feature. In addition, both models predicted a complex axial flow reversal pattern not previously reported in hydrocyclones. This study clearly shows that the quadratic RST model is preferable for future hydrocyclone simulations, especially when the swirl number is large. All necessary physical and numerical parameters used to obtain converged results are given in this article. © American Institute of Chemical Engineers AIChE J, 2006
Patched mutations and hairy skin patches: A new sign in Gorlin syndrome
Authors: Wilson Louise C. , Ajayi‐Obe Ekundayo , Bernhard Birgitta , Maas Saskia M.
Published: August 2006

We report on the occurrence of discrete patches of unusually long pigmented hair on the skin of three patients with Gorlin syndrome from two unrelated families with confirmed heterozygous mutations in the Patched (PTCH) gene. The PTCH protein is a negative regulator of Hedgehog signaling, and the Sonic Hedgehog (SHH)‐PTCH pathway is known to play an important role in the formation and cycling of the hair follicle. We believe that the patches represent a genuine physical sign associated with Gorlin syndrome, and discuss molecular mechanisms by which they might arise. © 2006 Wiley‐Liss, Inc.
Cornelia de Lange syndrome: Parental preferences regarding the provision of medical information
Authors: Hinkson Deborah A.R. , Atenafu Eshetu , Kennedy Shelley J. , Vohra Sunita , Garg Deepak , Levin Alex V.
Published: August 2006

We surveyed 57 caregivers of children with Cornelia de Lange syndrome (CdLS) using a self‐report questionnaire designed to elicit their experiences with receiving information regarding health complications associated with this multisystem disorder. Their most frequent sources of information at the time of diagnosis were a health care provider (86%) and the CdLS Foundation (72%). Although most caregivers (82%) indicated a desire to receive information about all possible CdLS related health complications, on average they recalled receiving information on only 64% of their child's current or future health complications. For two of the top three complications (as ranked by caregivers), information was available to fewer than half of the caregivers at diagnosis. Only 40% of caregivers were satisfied with the amount of information received at diagnosis, while only 45% felt that the information they received was useful. Caregivers indicated a preference for receiving information in written format (59%) or verbally (39%). Our results indicate that caregivers of children with CdLS report a high need for information at diagnosis, regarding their child's actual or potential health complications. Dissatisfaction may result both from a deficiency in information provided, as well as a mismatch between issues mentioned and those that caregivers deem most important. Caregivers may benefit maximally from receiving information in person at the time of diagnosis as well as having an additional written source of information. These findings highlight the importance of complementary sources of information for caregivers and are likely to be relevant for other multisystem disorders. © 2006 Wiley‐Liss, Inc.
Autism spectrum disorder in Fragile X syndrome: Differential contribution of adaptive socialization and social withdrawal
Authors: Budimirovic Dejan B. , Bukelis Irena , Cox Christiane , Gray Robert M. , Tierney Elaine , Kaufmann Walter E.
Published: August 2006

The present study extends our previous work on characterizing the profile of social behavior abnormalities in boys with Fragile X (FraX) and autism spectrum disorder (ASD) using clinically oriented behavioral rating scales and standardized instruments. The goal was to further distinguish behavioral parameters contributing to the diagnostic classification of FraX + ASD. The study design included two cohorts of boys with FraX (3–8 years), a larger main cohort for cross‐sectional analyses (n = 56, 24 with ASD), and a longitudinal subset (n = 30, 11 with ASD) of the main cohort with up to 3 yearly observations. The focus was on the relative contribution of delayed adaptive socialization and social withdrawal, including item components of their corresponding rating instruments, to the diagnosis of ASD in boys with FraX. Using a combination of regression analyses, we demonstrated that: (1) as delayed socialization, social withdrawal is also a correlate of FraX + ASD; (2) items of social withdrawal scales representing avoidance were the main predictors of ASD status, particularly in older boys; (3) adaptive socialization skills reflecting rules of social behavior and recognition and labeling of emotions, linked to verbal reasoning abilities, were selectively associated with FraX + ASD; (4) adaptive socialization is the primary determinant over time of ASD status in boys with FraX; and (5) integrated adaptive socialization‐social withdrawal models allow the identification of distinctive FraX + ASD subgroups. Altogether, our findings suggest that two distinct but interrelated social behavior abnormalities, one linked to impaired cognitive processes (delayed socialization) and the second one to disturbance in limbic circuits (avoidance), play a role in the development of ASD in boys with FraX. © 2006 Wiley‐Liss, Inc.
Epiphyseal dysplasia and other skeletal anomalies in a patient with the 6p25 microdeletion syndrome
Authors: Kannu Peter , Oei Paul , Slater Howard R. , Khammy Ouda , Aftimos Salim
Published: August 2006

The 6p25 microdeletion syndrome comprises the Axenfeld–Rieger eye anomaly in association with a characteristic facies, developmental delay, hearing loss, and organ malformations. Skeletal anomalies in the form of hemivertebrae, clubfeet, and other positional joint anomalies have also been described in some patients. We report on a patient with a 2.2–2.4 Mb terminal microdeletion of the short arm of chromosome 6 who in addition had abnormalities of the proximal femoral and humeral epiphyses. We suggest that an epiphyseal dysplasia may be an additional clinical component of the 6p25 microdeletion syndrome. © 2006 Wiley‐Liss, Inc.
Is there a higher incidence of maternal uniparental disomy 14 [upd(14)mat]? Detection of 10 new patients by methylation‐specific PCR
Authors: Mitter Diana , Buiting Karin , von Eggeling Ferdinand , Kuechler Alma , Liehr Thomas , Mau‐Holzmann Ulrike Angelika , Prott Eva‐Christina , Wieczorek Dagmar , Gillessen‐Kaesbach Gabriele
Published: August 2006

Maternal uniparental disomy for chromosome 14 [upd(14)mat] is associated with a characteristic phenotype including pre‐ and postnatal growth retardation, muscular hypotonia, feeding problems, motor delay, small hands and feet, precocious puberty and truncal obesity. Patients with upd(14)mat show features overlapping with Prader–Willi syndrome (PWS) and are probably underdiagnosed. Maternal upd(14) is frequently described in carriers of a Robertsonian translocation involving chromosome 14, but is also found in patients with a normal karyotype. Based on the above mentioned criteria we have identified six patients with upd(14)mat including two patients with a normal karyotype, one patient with a de novo Robertsonian translocation (14;21), one patient with a familial Robertsonian translocation (13;14) and two patients with a marker chromosome. In addition, we analyzed a cohort of 33 patients with low birth weight, feeding difficulties and consecutive obesity in whom PWS had been excluded by methylation analysis of SNRPN. In four of these patients (12%) we detected upd(14)mat. For rapid testing of upd(14)mat we analyzed the methylation status of the imprinted MEG3 locus. In conclusion, we recommend considering upd(14)mat in patients with low birth weight, growth retardation, neonatal feeding problems, muscular hypotonia, motor delay, precocious puberty and truncal obesity as well as in patients with a PWS like phenotype presenting with low birth weight, feeding difficulties and obesity. © 2006 Wiley‐Liss, Inc.
The Helena syndromes
Authors: Neri Giovanni
Published: August 2006

The author gives a personal account on how he was introduced to the field of clinical genetics as a student of John Opitz in Helena, MT. That process was facilitated by the study of several malformation syndromes. Particularly instructive were the approaches to the cardio‐facio‐cutaneous, the Perlman, and the FG syndrome. These three conditions are briefly revisited with a critical perspective, made possible by the elapse of 20 years, since the time when the author became acquainted with them. © 2006 Wiley‐Liss, Inc.
A previously unreported mutation in a Currarino syndrome kindred
Authors: Wang Raymond Y. , Jones Julie R. , Chen Steve , Rogers R. Curtis , Friez Michael J. , Schwartz Charles E. , Graham John M.
Published: August 2006

Currarino syndrome consists of autosomal dominant hereditary sacral dysgenesis that is caused by mutations of the HOX gene, HLXB9. Sacral malformation, presacral mass, and anorectal malformations comprise the classic triad, but other common symptoms and malformations include neonatal‐onset bowel obstruction, chronic constipation, recurrent perianal sepsis, renal/urinary tract anomalies, female internal genital anomalies, tethered spinal cord, and anterior meningocele. Up to 33% of patients are asymptomatic. There is marked inter‐ and intrafamilial variability in expression, and no genotype/phenotype correlations have been identified. To date, 32 different mutations have been identified in HLXB9: all nine missense mutations were found in the homeodomain, while the others were nonsense, frameshift, splice site mutations, or heterozygous whole‐gene deletions. We report a four‐generation family with Currarino syndrome varying in severity from very mild to full expression of the Currarino triad. They were found to carry a previously unreported nonsense mutation, E283X, absent in tested asymptomatic first‐degree relatives. This family provides additional information on the degree of intrafamilial variability associated with HLXB9 mutations. © 2006 Wiley‐Liss, Inc.
Array comparative genomic hybridization analysis in first‐trimester spontaneous abortions with ‘normal’ karyotypes
Authors: Shimokawa Osamu , Harada Naoki , Miyake Noriko , Satoh Kanako , Mizuguchi Takeshi , Niikawa Norio , Matsumoto Naomichi
Published: August 2006

Array comparative genomic hybridization (array CGH) analysis was conducted in chorionic villous samples from 20 first‐trimester spontaneous abortions with G‐banding normal chromosomes. A microarray, containing 2,173 BAC clones and covering the whole genome with a 1.5‐Mb resolution, was constructed and used in the analysis. Two deletions were identified: a 1.4‐Mb deletion at 3p26.2‐p26.3 and a 13.7‐Mb deletion at 13q32.3‐qter. Reexamination of chromosome preparations from the sample with the 13.7‐Mb deletion documented a mixture of cells with the 13q‐ chromosome and those with 46,XX chromosomes, the latter of which are likely to have been derived from contaminating decidual cells. This left the 1.4‐Mb 3p deletion as the only instance with submicroscopic imbalance detected, giving a frequency of 1 in 19 (5%) G‐banding normal abortions. © 2006 Wiley‐Liss, Inc.
Impact of neurofibromatosis 1 on Quality of Life: A cross‐sectional study of 176 American cases
Authors: Page Patricia Z. , Page Grier P. , Ecosse Emmanuel , Korf Bruce R. , Leplege Alain , Wolkenstein Pierre
Published: August 2006

Neurofibromatosis 1 (NF1), a genetic condition most commonly characterized by the presence of dermal neurofibromas and café au lait macules, has a significant impact on Quality of Life (QoL). There is a wide range of phenotypic variability, so that affected individuals may have either medically devastating or relatively mild manifestations that do not impact their daily lives. In this study, the SF‐36 and Skindex questionnaires were used to quantitatively investigate the impact of severity and visibility on QoL in an American population. Participants were recruited primarily through advertisements distributed by The Children's Tumor Foundation (CTF). The majority participated by completing a mailed questionnaire in which they rated themselves using Ablon's visibility and Riccardi's severity scales, and then completed the SF‐36 and Skindex questionnaires. Participants with NF1 reported a significant impact in all aspects of skin‐disease‐specific QoL, but the emotional aspect demonstrated the greatest effect. Participants with more visible signs of NF1 reported significantly greater overall effects on their skin‐disease‐specific QoL than those whose manifestations were more subtle. All domains of general health QoL were affected as well, especially in participants who reported having severe complications. Interestingly, greater visibility was not found to be associated with a significant decrease in general health QoL. These findings are consistent with those found in a French cohort, and demonstrate the utility of incorporating tools designed for use in both the general population and for patients with skin disease in examining the impact of NF1 on QoL. © 2006 Wiley‐Liss, Inc.
Clinical phenotype and molecular characterization of 6q terminal deletion syndrome: Five new cases
Authors: Striano Pasquale , Malacarne Michela , Cavani Simona , Pierluigi Mauro , Rinaldi Rosanna , Cavaliere Maria Luigia , Rinaldi Maria Michela , De Bernardo Carmelilia , Coppola Antonietta , Pintaudi Maria , Gaggero Roberto , Grammatico Paola , Striano Salvatore , Dallapiccola Bruno , Zara Federico , Faravelli Francesca
Published: August 2006

Mental retardation, facial dysmorphisms, seizures, and brain abnormalities are features of 6q terminal deletions. We have ascertained five patients with 6q subtelomere deletions (four de novo, one as a result of an unbalanced translocation) and determined the size of the deletion ranging from 3 to 13 Mb. Our patients showed a recognizable phenotype including mental retardation, characteristic facial appearance, and a distinctive clinico‐neuroradiological picture. Focal epilepsy with consistent electroencephalographic features and with certain brain anomalies on neuroimaging studies should suggest 6q terminal deletion. The awareness of the distinctive clinical picture will help in the diagnosis of this chromosomal abnormality. © 2006 Wiley‐Liss, Inc.
Cover Picture: Toward the Total Synthesis of Spirastrellolide A. Part 1: Strategic Considerations and Preparation of the Southern Domain / Toward the Total Synthesis of Spirastrellolide A. Part 2: Conquest of the Northern Hemisphere (Angew. Chem. Int. Ed. 33/2006)
Authors: Fürstner Alois , Fenster Michaël D. B. , Fasching Bernhard , Godbout Cédrickx , Radkowski Karin
Published: August 2006

The antimitotic natural product spirastrellolide A is a complicated structure that shows impressive biological effects. Many key issues remain unresolved for this compound, for example its relative and absolute configurations and its biological mode of action. In two Communications on pages 5506 and 5510 ff., Fürstner and co‐workers describe the synthesis of all four fragments of spirastrellolide A—initial strides in answering these questions. (Image of cell undergoing mitosis: Conley Rieder.)
Circular dichroism as a reliable tool for anomeric assignment of glycosyl‐2‐phenyl‐2H‐1,2,3‐triazole C‐nucleoside analogs. A rule for prediction of their anomeric configuration
Authors: Sallam Mohammed A. E.
Published: August 2006

The circular dichroism (CD) of a series of acyclic C‐nucleoside analogs; 4‐(pentahydroxypentyl‐1‐yl)‐2‐phenyl‐2H‐1,2,3‐triazoles [1–5] and 4‐(D‐glycero‐D‐gulo)‐2‐phenyl‐2H‐1,2,3‐triazole 6, are reported. A correlation between the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the carbon atom α‐ to the triazole base moiety is reported. The CD of anomeric 4‐(α,β‐D‐arabinofuranosyl)‐ and 4‐(α,β‐D‐arabinopyranosyl)‐2‐phenyl‐2H‐1,2,3‐triazole C‐nucleosides are reported. The assignment of the anomeric configuration of C‐glycosyl‐2‐phenyl‐2H‐1,2,3‐triazoles from their CD spectra was found to be a simple method that relies on comparison of the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the anomeric carbon atom. A correlation between the anomeric configuration and the sign of the Cotton effect at the maximal UV absorption is deduced and generalized as a rule for prediction of the anomeric configuration of C‐glycosyl‐2‐phenyl‐2H‐1,2,3‐triazoles. Nuclear Overhauser effect and 13C NMR spectra supported the CD assignment rule. Chirality, 2006. © 2006 Wiley‐Liss, Inc
Stereoselective pharmacokinetics of ornidazole after intravenous administration of individual enantiomers and the racemate
Authors: Chen Yan , Liu Xiao Quan , Zhong Jiao , Zhao Xiaoping , Wang Yongsheng , Wang Guangji
Published: August 2006

The pharmacokinetics of ornidazole (ONZ) were investigated following i.v. administration of racemic mixture and individual enantiomers in beagle dogs. Plasma concentrations of ONZ enantiomers were analyzed by chiral high‐performance liquid chromatography (HPLC) on a Chiralcel OB‐H column with quantification by UV at 310 nm. Notably, the mean plasma levels of (−)‐ONZ were higher in the elimination phase than those of (+)‐ONZ. (−)‐ONZ also exhibited greater t1/2, MRT, AUC0‐t and smaller CL, than those of its antipode. The area under the plasma concentration‐time curve (AUC0‐t) of (−)‐ONZ was about 1.2 times as high as that of (+)‐ONZ. (+)‐ONZ total body clearance (CL) was 1.4 times than its optical antipode. When given separately, there were significant differences in the values of AUC0‐∞ and CL between ONZ enantiomers (P < 0.05), indicating that elimination of (+)‐ONZ was more rapid than that of (−)‐ONZ. No significant differences were found between the estimates of the pharmacokinetic parameters of (+)‐ONZ or (−)‐ONZ, obtained following administration as the individual and as a racemic mixture. This study demonstrates that the elimination of ONZ enantiomers is stereoselective and chiral inversion and enantiomer/enantiomer interaction do not occur when the enantiomers are given separately and as racemic mixture. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Multiparallel chiral method development screening using an 8‐channel microfluidic HPLC system
Authors: Sajonz Peter , Gong Xiaoyi , Leonard William R. , Biba Mirlinda , Welch Christopher J.
Published: August 2006

The Eksigent Express 800 8‐channel microfluidic HPLC system was investigated for carrying out multiparallel screening and development of fast normal phase chiral separations. In contrast to the familiar automated sequential chiral method development approaches that often afford a next day result, the multiparallel approach offers the exciting possibility of near “real time” method development, often affording an optimized method in less than 1 h. In this study, four column types (300 μm i.d.) with two different mobile phases are screened using a universal standard gradient approach. Interestingly, parallel method optimization following initial screening was shown to sometimes lead to surprising and unanticipated outcomes, emphasizing the value of the multiparallel screening approach. A variety of standard test racemates were analyzed, with optimized separation methods for most in the 1‐ to 2‐min range. These results compare favorably with results obtained on a single channel conventional HPLC system using 4.6‐mm i.d. columns. In addition, isocratic methods developed on the microbore columns are readily translated to the larger column format. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Use of Triplet Excited States for the Study of Drug Binding to Human and Bovine Serum Albumins
Authors: Vayá Ignacio , Bueno Carlos J. , Jiménez M. Consuelo , Miranda Miguel A.
Published: August 2006

The triplet excited states of (S)‐ and (R)‐flurbiprofen (FBP) have been used as reporters for the microenvironments experienced within the binding sites of human and bovine serum albumins. Regression analysis of triplet decay provides valuable information on the degree of protection that these excited states are afforded from attack by a second FBP molecule, oxygen, or other reagents. The multiexponential fitting of these decays can be satisfactorily correlated with the distribution of the drug among the two binding sites and its presence as the noncomplexed form in the bulk solution. This assignment has been confirmed by using (S)‐ibuprofen or capric acid as selective site II replacement probes. Triplet lifetimes and site occupancy are sensitive to the type of serum albumin employed (human versus bovine). Finally, the binding behaviour of (S)‐ and (R)‐FBP exhibits little stereoselectivity.
Bandwidth correction for LED chromaticity
Authors: Gardner James L.
Published: August 2006

The spectral bandwidth formulae of Stearns and Stearns (Color Res Appl 1988; 13: 257–259) are generalized for an arbitrary slit function. Correction coefficients are derived in terms of moments of the slit function. Application to model LED spectra measured with a compact, fiber‐coupled spectrometer having bandwidth of order 12 nm, and a nonlinear wavelength scale shows that accurate LED color measurements may be obtained with such an instrument. Fitting of the relatively broad slit function to line spectra for accurate wavelength calibration is also described. Such fitting, coupled consistently with the bandpass correction, improves the accuracy color measurements with a broad‐response spectrometer. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 374–380, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20242
Spectral sensitivity of sensors for a color‐image descriptor invariant to changes in daylight conditions
Authors: Romero Javier , Hernández‐Andrés Javier , Nieves Juan Luis , Valero Eva M.
Published: August 2006

Previous authors (J Opt Soc Am A 2000; 17: 1952–1961; J Opt Soc Am A 2001; 18: 253–264) have proposed a pixel‐by‐pixel image descriptor that is invariant to certain changes in illumination. We have studied the possibility of applying such an invariant descriptor to scenery illuminated by natural light, by choosing sensors that allow the invariant to behave satisfactorily under daylight. We obtained different triads of monochromatic sensors by using an exhaustive‐search method and compared the results with those obtained with other triads proposed by different authors. We extended our study to Gaussian sensors centered in the wavelengths considered for the monochromatic sensors and to commercial CCD camera sensors. Satisfactory results are achieved for Gaussian sensors with maximum sensitivities at different locations. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 391–398, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col20243.
Investigation of human's emotional responses on colors
Authors: Gao Xiao‐Ping , Xin John H.
Published: August 2006

This article investigates human's emotional responses on colors based on a psychophysical experiment. Totally 218 color samples were evaluated by 70 subjects based on 12 basic descriptive variables including “warm–cool,” “weak–strong,” and “dynamic–passive.” By using factor analysis, these 12 variables were split into two orthogonal factors (activity index and potency index) and one correlative factor (definition index), which may be used for description of color emotion. Based on these three indexes, a color emotion map in CIELCH color space was obtained by cluster analysis. A well‐regulated distribution of human's emotion was observed in CIE L*C* plane with a neutral feeling region around the point of chroma C*=30.5 and lightness L*=53.3. Colors scattered at opposite direction of this neutral region possess the opposite feelings. The detailed relationship between color emotion indexes and color perception attributes, i.e., hue, lightness, and chroma, were further studied by correlation analysis and graphical representation. The results indicated that the activity index was dependent on chroma, the potency index was dependent on lightness, and the definition index was dependent on both chroma and lightness. It was also observed that the influence of hue on emotional response was not as significant as those in previous studies even for the variable “warm–cool.” © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 411–417, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20246
Influence of wood extractives on the photo‐discoloration of wood surfaces exposed to artificial weathering
Authors: Nzokou Pascal , Kamdem Donatien Pascal
Published: August 2006

Extracted and unextracted black cherry (Prunus serotina), red oak (Quercus rubra), and red pine (Pinus resinosa) wood specimens were exposed to artificial weathering, and their discoloration process was investigated to obtain basic understanding on the role of wood extractives in the weathering of hardwoods and softwoods. Color measurements were made with a spectrometer according to ISO 2470 standards, using the CIELAB system. Results obtained showed that the rate of whiteness was not significantly affected by extractives removed with organic solvents, but were significantly affected when organic solvent extraction was followed by water extraction. The total discoloration rate had the same pattern, and chromaticity coordinates were less affected by wood extractives. These results confirm the hypothesis that some extractives contained in wood act as antioxidants and are able to provide some protection to wood surfaces against weathering degradation. However, more work is needed to understand the chemistry and mechanism of action of these extractives so as to develop any practical use for this property. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 425–434, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20248
Preparation of Holographic Gratings of Liquid Crystals Dispersed in Polyurethane Acrylates under Controlled Reaction Conditions
Authors: Kim Eun Hee , Kim Byung Kyu
Published: August 2006

Transmission gratings of holographic polymer‐dispersed liquid crystals (HPDLC) are prepared under controlled reaction conditions by adding various amounts of chain‐transfer agent (CTA). The resulting films have a higher gel content with lower cross‐link density, less dark reaction, less grating shrinkage with much smoother LC/polymer interfaces, smaller induction period, and fast saturation of diffraction efficiency, which shows a maximum of 95 % with 1 % CTA. An optimum LC content of 35 % is verified on the basis of morphology and reaction kinetics.