bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eintopfsynthese von “Kettenhemd”‐stabilisierten DNA‐Nanostrukturen
Authors: Cassinelli Valentina , Oberleitner Birgit , Sobotta Jessica , Nickels Philipp , Grossi Guido , Kempter Susanne , Frischmuth Thomas , Liedl Tim , Manetto Antonio 
Published: May 2015

AbstractSich selbstständig anordnende DNA‐basierte Nanostrukturen finden weitverbreitete Anwendung bei der präzisen Positionierung organischer und anorganischer Komponenten im Nanometerbereich. Besonders vielversprechend ist ihre Verwendung als programmierbare Systeme für den zielgerichteten Wirkstofftransport. Um DNA‐basierte Strukturen zu entwickeln, die robust gegen Zersetzung bei erhöhten Temperaturen, niedrigen Ionenkonzentrationen, ungünstigen pH‐Bedingungen oder durch DNAsen sind, haben wir 6‐Helix‐Bündel aus 24 Oligonukleotiden konstruiert, die an ihrem 3′‐Ende Alkingruppen und an ihrem 5′‐Ende Azidgruppen tragen. Mithilfe einer sanften Klick‐Reaktion wurden die beiden Enden ausgewählter Oligonukleotide kovalent miteinander verbunden, um Ringe und verschränkte DNA‐Stränge zu erzeugen. Auffallenderweise blieben diese DNA‐Catenane in Wasser oder selbst nach Ethanolfällung topologisch intakt. Gleiches galt, wenn die Strukturen Temperaturen über 95 °C ausgesetzt wurden, sofern alle 24 Stränge kovalent cyclisiert wurden.
Synthesis and Applications of Hajos–Parrish Ketone Isomers
Authors: Eagan James M. , Hori Masahiro , Wu Jianbin , Kanyiva Kyalo Stephen , Snyder Scott A. 
Published: May 2015

AbstractNumerous natural products possess ring systems and functionality for which Hajos–Parrish ketone isomers with a transposed methyl group (termed “iso‐Hajos–Parrish ketones”) would be of value. However, such building blocks have not been exploited to the same degree as the more typical Hajos–Parrish hydrindane. An efficient three‐step synthesis of such materials was fueled by a simple method for the rapid preparation of highly functionalized cyclopentenones, several of which are new chemical entities that would be challenging to access through other approaches. Furthermore, one iso‐Hajos–Parrish ketone was converted into two distinct natural product analogues and one natural product. As one indication of the value of these new building blocks, that latter target was obtained in 10 steps, having previously been accessed in 18 steps using the Hajos–Parrish ketone.
Frustrated Lewis Pair Chemistry: Development and Perspectives
Authors: Stephan Douglas W. , Erker Gerhard 
Published: May 2015

AbstractFrustrated Lewis pairs (FLPs) are combinations of Lewis acids and Lewis bases in solution that are deterred from strong adduct formation by steric and/or electronic factors. This opens pathways to novel cooperative reactions with added substrates. Small‐molecule binding and activation by FLPs has led to the discovery of a variety of new reactions through unprecedented pathways. Hydrogen activation and subsequent manipulation in metal‐free catalytic hydrogenations is a frequently observed feature of many FLPs. The current state of this young but rapidly expanding field is outlined in this Review and the future directions for its broadening sphere of impact are considered.
Fabrication of Tiron‐doped polypyrrole/MWCNT composite electrodes with high mass loading and enhanced performance for supercapacitors
Authors: Shi Kaiyuan , Pang Xin , Zhitomirsky Igor 
Published: May 2015

ABSTRACTIn this study, the aromatic sulfonate compound Tiron with high charge to mass ratio is used as an anionic dopant for synthesis of polypyrrole (PPy). The fabricated PPy is investigated for electrochemical supercapacitor (ES) application. Testing results show that Tiron allows reduced PPy agglomeration, smaller particle size and improved charge storage properties of PPy. High capacitance and improved capacitive retention at high scan rates are achieved by the fabrication of PPy/multiwalled carbon nanotube (MWCNT) composite electrode using safranin (SAF) as a co‐dispersant. The Tiron‐doped PPy electrode shows the highest capacitance of 7.8 F cm−2 with a mass of 27 mg cm−2. The Tiron‐doped PPy/MWCNT composite electrode shows good capacitance retention with a capacitance of 1.0 F cm−2 at the scan rate of 100 mV s−1. Symmetric supercapacitor cells are fabricated using PPy based active materials. An energy density of 0.36 mWh cm−2 is achieved. The energy/power density and capacitance retention of the Tiron‐doped PPy/MWCNT ES is significantly improved in comparison with PPy‐based ES, prepared without Tiron or MWCNT. The Tiron‐doped PPy/MWCNT symmetric supercapacitor presents good cycling performance with 91.4% capacitance retention after 1000 charge–discharge cycles. The PPy/MWCNT composites, prepared using Tiron and SAF co‐dispersant, are promising electrodes for ES. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42376.
Effect of electrical properties on gas sensitivity of polypyrrole/cds nanocomposites
Authors: Yeole Bharati , Sen Tanushree , Hansora D. P. , Mishra Satyendra 
Published: May 2015

ABSTRACTIn the present work, polypyrrole (PPy) nanocomposites were synthesized using ferric chloride (FeCl3) as an oxidant by in situ polymerization at room temperature. Cadmium sulfide (CdS) nanoparticles were synthesized by ultrasonication technique with size ranging between 60 and 110 nm. The PPy/CdS nanocomposites were prepared by taking 1–3 wt % loading of CdS to measure the electrical conductivity. The PPy nanocomposites were characterized by using FTIR, X‐ray diffraction, UV, and SEM. Furthermore, these PPy/CdS nanocomposites were investigated to study their effect of electrical properties on gas sensitivity of ammonia and LPG. The nanocomposites showed improvement in conductivity and sensing response toward 250 ppm NH3was found to be maximum (4.2) compared with 100 and 500 ppm NH3gas, whereas in the case of LPG, it showed sensitive response. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 42379.
Facile preparation of EDTA‐functionalized chitosan magnetic adsorbent for removal of Pb(II)
Authors: Tan Zhengyan , Peng Hong , Liu Hongfang , Wang Linling , Chen Jing , Lu Xiaohua 
Published: May 2015

ABSTRACTA novel magnetic adsorbent (EDTA/chitosan/PMMS) was facilely prepared by reacting chitosan with EDTA anhydride in presence of PEI‐coated magnetic microspheres. The as‐synthesized EDTA/chitosan/PMMS was characterized by XRD, SEM, TGA, FT‐IR, and VSM, and then employed in removal of heavy metals of Pb(II) from aqueous solution. The results of the batch adsorption experiments revealed that the adsorbents had extremely high uptake capacities for Pb(II) in the pH range of 2 to 5.5, and the adsorption kinetics for EDTA/chitosan/PMMS was consistent with the pseudo–second‐order kinetic model. Moreover, its equilibrium data were fitted with the Langmuir isothermal model well, which indicated that the adsorption mechanism was a homogeneous monolayer chemisorptions process. The maximum adsorption capacity of EDTA/chitosan/PMMS for Pb(II) was found to be 210 mg g−1 at pH 4 (30°C), and further reuse experiments results suggested that EDTA/chitosan/PMMS could be a potential recyclable magnetic adsorbent in the practical wastewater treatment. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42384.
Photo‐Induced atom transfer radical polymerization with nanosized α‐Fe2O3 as photoinitiator
Authors: Liu Li‐chao , Lu Mang , Hou Zhao‐Hui , Wang Guo‐Xiang , Yang Chang‐An , Liang En‐Xiang , Wu Hu , Li Xian‐Lei , Xu Yi‐Xue 
Published: May 2015

ABSTRACTPhoto‐induced atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was achieved in poly(ethylene glycol)‐400 with nanosized α‐Fe2O3 as photoinitiator. Well‐defined poly(methyl methacrylate) (PMMA) was synthesized in conjunction with ethyl 2‐bromoisobutyrate (EBiB) as ATRP initiator and FeCl3·6H2O/Triphenylphosphine (PPh3) as complex catalyst. The photo‐induced polymerization of MMA proceeded in a controlled/living fashion. The polymerization followed first‐order kinetics. The obtained PMMA had moderately controlled number‐average molecular weights in accordance with the theoretical number‐average molecular weights, as well as narrow molecular weight distributions (Mw/Mn). In addition, the polymerization could be well controlled by periodic light‐on–off processes. The resulting PMMA was characterized by 1H nuclear magnetic resonance and gel permeation chromatography. The brominated PMMA was used further as macroinitiator in the chain‐extension with MMA to verify the living nature of photo‐induced ATRP of MMA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42389.
Improvement of mechanical properties of polylactic acid adhesion joints with bio‐based adhesives by using air atmospheric plasma treatment
Authors: Jordá‐Vilaplana Amparo , Sánchez‐Nácher Lourdes , Fombuena Vicent , García‐García Daniel , Carbonell‐Verdú Alfredo 
Published: May 2015

ABSTRACTThe packaging industry generates a high volume of wastes; so that, there is a high demand of biodegradable materials, which do not damage the environment. Nowadays, there is an interesting consumption of polylactic acid (PLA) due to its biodegradable features. This work focuses on the improvement of mechanical properties of PLA adhesion joints for uses in the packaging industry. In order to achieve that purpose, atmospheric plasma treatment is used to selectively modify PLA surface properties. The obtained experimental results show that the atmospheric plasma treatment is suitable to increase the mechanical performance of PLA–PLA adhesive joints. Optimum conditions for the atmospheric plasma treatment were obtained with a nozzle–substrate distance of 10 mm and an advance rate in the 100–300 mm s−1range; for these particular conditions, the effectiveness of the surface modification is the highest. The main plasma‐acting mechanisms are microetching together with the insertion of polar groups which lead to an interesting synergy that causes a remarkable increase in mechanical properties of adhesion joints. In particular, the shear strength of untreated PLA–PLA adhesion joints is close to 50 N cm−2and this value is increased up to values of about 168.7 N cm−2with optimum plasma treatment conditions. This indicates that atmospheric plasma treatment is both a technical and an environmental friendly technique to improve mechanical performance of PLA adhesive joints. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 42391.
Polycarbonate‐based composites reinforced by in situ polytetrafluoroethylene fibrillation: Preparation, thermal and rheological behavior
Authors: Antonioli Diego , Sparnacci Katia , Laus Michele , Boarino Luca , Righetti Maria Cristina 
Published: May 2015

ABSTRACTFibrillar reinforced composites of polytetrafluoroethylene (PTFE) and polycarbonate (PC) were prepared by in situ fibrillation of PTFE into PC matrix using twin screw extruder. Different samples were obtained by varying the relative ratio between PC and PTFE. The rheological properties of the PC/PTFE composites were found to depend on concentration of the PTFE fibrils. The melt strength analysis in nonisothermal conditions was also studied. The increase in force and decrease in drawability with increasing the PTFE content are associated with the PTFE fibrils formed in situ during the thermomechanical process in twin screw extruder. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42401.
LC‐ESI‐MS/MS analysis of quercetin in rat plasma after oral administration of biodegradable nanoparticles
Authors: V. Dinesh Kumar , Verma Priya Ranjan Prasad , Singh Sandeep Kumar , Viswanathan S. 
Published: May 2015

AbstractA simple, rapid and sensitive LC‐MS/MS method was developed and validated for the determination of free quercetin in rat plasma, using fisetin as internal standard. The detection was performed by negative ion electrospray ionization under selected reaction monitoring. Chromatographic separation (isocratic elution) was carried out using acetonitrile–10 m m ammonium formate (80:20, v/v) with 0.1% v/v formic acid. The lower limit of quantification (4.928 ng/mL) provided high sensitivity for the detection of quercetin in rat plasma. The linearity range was from 5 to 2000 ng/mL. Intra‐ and inter‐day variability (RSD) of quercetin extraction from rat plasma was <4.19 and 1.37% with accuracies of 98.77 and 99.67%. The method developed was successfully applied for estimating free quercetin in rat plasma, after oral administration of quercetin‐loaded biodegradable nanoparticles (QLN) and quercetin suspension. QLN (Cmax, 1277.34 ± 216.67 ng/mL; AUC, 17,458.25 ± 3152.95 ng hr/mL) showed a 5.38‐fold increase in relative bioavailability as compared with quercetin suspension (Cmax, 369.2 ± 108.07 ng/mL; AUC, 3276.92 ± 396.67 ng hr/mL). Copyright © 2015 John Wiley & Sons, Ltd.
A case report of Progressive subluxation leading to an anterior dislocation of the hip following sliding hip screw fixation for pertrochanteric Extracapsular 4 part fracture neck of femur
Authors: Shah Jaydeep , Marson Ben A. 
Published: May 2015

Key Clinical MessageUnstable 4 part pertrochanteric fractures without lateral cortical support presents considerable technical problem in treatment with high risk of failure with any implant. Anatomical or slight valgus reduction and subchondral central position of the lag screw (TAD <25 mm) reduces the chance of screw cut out and other complications.
Nanoparticle‐Imprinted Polymers: Shell‐Selective Recognition of Au Nanoparticles by Imprinting Using the Langmuir–Blodgett Method
Authors: Bruchiel‐Spanier Netta , Mandler Daniel 
Published: May 2015

AbstractThe front cover artwork is provided by Prof. Mandler′s group at the Hebrew University (Israel). The image shows the reuptake process in which only the particles with the original shell size are captured by the imprinted cavities, while the others are not recognized. Read the full text of the Article at10.1002/celc.201402407.
Superior Lithium‐Ion Storage Properties of Mesoporous CuO–Reduced Graphene Oxide Composite Powder Prepared by a Two‐Step Spray‐Drying Process
Authors: Park Gi Dae , Kang Yun Chan 
Published: May 2015

AbstractMesoporous CuO–reduced graphene oxide (rGO) composite powders were prepared by using a two‐step spray‐drying process. In the first step, hollow CuO powders were prepared from a spray solution of copper nitrate trihydrate with citric acid and were wet milled to obtain a colloidal spray solution. In the second step, spray drying of the colloidal solution that contained dispersed GO nanosheets produced mesoporous CuO–rGO composite powders with particle sizes of several microns. Thermal reduction of GO nanosheets to rGO nanosheets occurred during post‐treatment at 300 °C. Initial discharge capacities of the hollow CuO, bare CuO aggregate, and CuO–rGO composite powders at a current density of 2 A g−1 were 838, 1145, and 1238 mA h g−1, respectively. Their discharge capacities after 200 cycles were 259, 380, and 676 mA h g−1, respectively, and their corresponding capacity retentions measured from the second cycle were 67, 48, and 76 %, respectively. The mesoporous CuO–rGO composite powders have high structural stability and high conductivity because of the rGO nanosheets, and display good cycling and rate performances.
Acid Chloride Synthesis by the Palladium‐Catalyzed Chlorocarbonylation of Aryl Bromides
Authors: Quesnel Jeffrey S. , Kayser Laure V. , Fabrikant Alexander , Arndtsen Bruce A. 
Published: May 2015

AbstractWe report a palladium‐catalyzed method to synthesize acid chlorides by the chlorocarbonylation of aryl bromides. Mechanistic studies suggest the combination of sterically encumbered PtBu3 and CO coordination to palladium can rapidly equilibrate the oxidative addition/reductive elimination of carbon–halogen bonds. This provides a useful method to assemble highly reactive acid chlorides from stable and available reagents, and can be coupled with subsequent nucleophilic reactions to generate new classes of carbonylated products.
RhV‐Nitrenoid as a Key Intermediate in RhIII‐Catalyzed Heterocyclization by CH Activation: A Computational Perspective on the Cycloaddition of Benzamide and Diazo Compounds
Authors: Zhou Tao , Guo Wei , Xia Yuanzhi 
Published: May 2015

AbstractA mechanistic study of the substituent‐dependent ring formations in RhIII‐catalyzed CH activation/cycloaddition of benzamide and diazo compounds was carried out by using DFT calculations. The results indicated that the decomposition of the diazo is facilitated upon the formation of the five‐membered rhodacycle, in which the RhIII center is more electrophilic. The insertion of carbenoid into RhC(phenyl) bond occurs readily and forms a 6‐membered rhodacycle, however, the following CN bond formation is difficult both kinetically and thermodynamically by reductive elimination from the RhIII species. Instead, the RhV‐nitrenoid intermediate could be formed by migration of the pivalate from N to Rh, which undergoes the heterocyclization much more easily and complementary ring‐formations could be modulated by the nature of the substituent at the α‐carbon. When a vinyl is attached, the stepwise 1,3‐allylic migration occurs prior to the pivalate migration and the 8‐membered ring product will be formed. On the other hand, the pivalate migration becomes more favorable for the phenyl‐contained intermediate because of the difficult 1,3‐allylic migration accompanied by dearomatization, thus the 5‐membered ring product was formed selectively.
Copper(I)‐Catalyzed Cycloaddition of Azides to Multiple Alkynes: A Selectivity Study Using a Calixarene Framework
Authors: Gorbunov Alexander , Cheshkov Dmitry , Kovalev Vladimir , Vatsouro Ivan 
Published: May 2015

AbstractCopper(I)‐catalyzed addition of limited amounts of azides to multiple alkynes, which led to statistical mixtures of triazole/acetylene derivatives or, in other cases, resulted in preferred formation of multiple triazoles, was studied at pre‐organizable calixarene platforms bearing up to four propargyl groups. Depending on calixarene structures and reaction conditions, the unprecedented specific or selective formation of exhaustively triazolated calixarenes or a complete loss of the selectivity were observed. Both autocatalytic copper activation and a local copper(I) concentration increase due to copper–triazole complexation were thoroughly studied as the most expected reasons for the selectivity and both were disproved. Mixed triazolated/propargylated calixarenes and their copper(I) complexes proved not to be involved in the cascade‐like process that was modeled to be driven by an intramolecular transfer of two copper(I) ions from a just‐formed binuclear copper intermediate to the adjacent acetylene unit.
A Combined Transition‐Metal‐Catalyzed and Photopromoted Process: Synthesis of 2,3‐Fused 4‐Phenylnaphthalen‐1‐yl Carboxylates from 1,7‐Diaryl‐1,6‐diynes
Authors: Yamamoto Yoshihiko , Mori Shota , Shibuya Masatoshi 
Published: May 2015

Abstract2,3‐Fused 4‐phenylnaphthalen‐1‐yl carboxylates were synthesized in a step‐ and atom‐economical manner using a ruthenium‐catalyzed hydrocarboxylative cyclization of 1,7‐diaryl‐1,6‐diynes and subsequent oxidative photocyclization. The scope of this novel two‐step process was demonstrated by the construction of diverse structures from substrates with various tethers and terminal aryl groups. Late‐stage CH functionalizations of the arylnaphthalene product further enhance the synthetic potential of the developed process.
Synthesis and Coordination Chemistry of Iminophosphanes
Authors: van Dijk Tom , Burck Sebastian , Rosenthal Amos J. , Nieger Martin , Ehlers Andreas W. , Slootweg J. Chris , Lammertsma Koop 
Published: May 2015

AbstractIminophosphanes are a new group of 1,3‐P,N‐ligands, readily obtainable from secondary phosphanes and nitrilium ions, having a tunable N‐donor site by means of varying the imine substituents. These ligands give, in high yields, monodentate gold complexes and bidentate rhodium and iridium complexes. Crystal structures are reported for both the ligands and the complexes.
ChemInform Abstract: Flux Synthesis and Crystal Structure Determination of the Colored Skutterudite Ir2Sn3Se3.
Authors: Yan Wenjie , Pielnhofer Florian , Tragl Samuel A. , Weihrich Richard 
Published: May 2015

AbstractIr2Sn3Se3 (IrSn1.5Se1.5) is prepared by high‐temperature reaction of the elements (belt apparatus, 600 °C, 40 kbar, 1 h), microcrystalline powder and single crystals are obtained by solid state reaction of Ir and an excess of SnSe acting as reactive flux (1000 °C, 5 d; slow cooling).
ChemInform Abstract: Outstanding Laser Damage Threshold in Li2MnGeS4 and Tunable Optical Nonlinearity in Diamond‐Like Semiconductors.
Authors: Brant Jacilynn A. , Clark Daniel J. , Kim Yong Soo , Jang Joon I. , Weiland Ashley , Aitken Jennifer A. 
Published: May 2015

AbstractLi2MnGeS4 (I) and Li2CoSnS4 (II) are prepared by solid state reaction of Mn (Co), Ge (Sn), S, and 20% excess Li2S (graphite crucible in evacuated silica tubes, 700 °C resp.
ChemInform Abstract: High‐Voltage Cathode Materials for Lithium‐Ion Batteries: Freeze‐Dried LiMn0.8Fe0.1M0.1PO4/C (M: Fe, Co, Ni, Cu) Nanocomposites.
Authors: Iturrondobeitia Amaia , Goni Aintzane , Gil de Muro Izaskun , Lezama Luis , Kim Chunjoong , Doeff Marca , Cabana Jordi , Rojo Teofilo 
Published: May 2015

AbstractLiMn0.8Fe0.1M0.1PO4/C (M: Fe, Co, Ni, Cu) nanocomposite cathode materials are prepared by freeze‐drying of aqueous solutions of citric acid, Mn(OAc)3, LiOH, NH4H2PO4, and M(OAc)2 in stoichiometric quantities (‐80 °C, 48 h, 3 x 10‐1 mbar).
ChemInform Abstract: Molecular CHEVREL‐Like Clusters [(RhPPh3)6(μ3‐Se)8] and [Pd6(μ3‐Te)8]4‐.
Authors: Thiele Guenther , You Zhiliang , Dehnen Stefanie 
Published: May 2015

Abstract[(RhPPh3)6(μ3‐Se)8] ·0.5en is obtained by layering a solution of [K(18‐crown‐6)]2[Pb2Se3] in en with a saturated THF solution of Rh(PPh3)3Cl (2 weeks, 16% yield).
ChemInform Abstract: Photocatalytic α‐Oxyamination of Stable Enolates, Silyl Enol Ethers, and 2‐Oxoalkane Phosphonic Esters.
Authors: Schroll Peter , Koenig Burkhard 
Published: May 2015

AbstractFast α‐oxyamination of stable enolates, silyl enol ethers, and in situ deprotonated dialkyl 2‐oxoalkane phosphonates and diphenyl‐2‐oxoalkyl phosphine oxides is performed in the presence of [Ru(bipy)3]2+ as a photocatalyst, TEMPO, and visible light.
ChemInform Abstract: A Rhodium Triphenylphosphine Catalyst for Alkene Hydrogenation Supported on Neat Superparamagnetic Iron Oxide Nanoparticles.
Authors: Thiel Werner R. , et al.  
Published: May 2015

AbstractThe catalytic system is applicable to the hydrogenation of terminal and internal alkenes, including sterically hindered and carbonyl‐containing substrate.
ChemInform Abstract: Copper/Silver‐Mediated Direct ortho‐Ethynylation of Unactivated (Hetero)aryl C—H Bonds with Terminal Alkyne.
Authors: Liu Yue‐Jin , Liu Yan‐Hua , Yin Xue‐Song , Gu Wen‐Jia , Shi Bing‐Feng 
Published: May 2015

AbstractAn efficient synthesis of aryl alkynes using the removable PIP as directing group is developed.
ChemInform Abstract: Enantioselective Oraganocatalyzed Desymmetrization of 3‐Substituted Cyclobutanones Through Michael Addition to Nitroalkenes.
Authors: Capitta Francesca , Frongia Angelo , Ollivier Jean , Aitken David J. , Secci Francesco , Piras Pier Paolo , Guillot Regis 
Published: May 2015

AbstractThe reaction provides 3‐alkyl/aryl‐2‐(2‐nitro‐1‐alkyl/aryl)cyclo‐1‐butanones as mixture of the two diastereomers bearing a trans‐ring configuration.
ChemInform Abstract: Straightforward Synthesis of 1,2‐Dicyanoalkanes from Nitroalkenes and Silyl Cyanide Mediated by Tetrabutylammonium Fluoride.
Authors: Kiyokawa Kensuke , Nagata Takaya , Hayakawa Junpei , Minakata Satoshi 
Published: May 2015

AbstractA straightforward synthesis of 1,2‐dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described.