bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Markov model approach shows a large variation in the length of S phase in MCF‐7 breast cancer cells
Authors: Larsson Sara , Johansson Maria , Oredsson Stina , Holst Ulla 
Published: April 2005

AbstractBackgroundThe potential doubling time of a tumor has been suggested to be a measurement of tumor aggressiveness; therefore, it is of interest to find reliable methods to estimate this time. Because of variability in length of the various cell cycle phases, stochastic modeling of the cell cycle might be a suitable approach.MethodsThe relative movement curve and the DNA synthesis time were estimated by using local polynomial regression methods. Further, the rate of nucleotide incorporation was estimated by using a Markov pure birth process with one absorbing state to model the progression of the DNA distribution through S phase.ResultsAn estimate of the DNA synthesis time, with confidence intervals, was obtained from the relative movement curve. The Markov approach provided an estimate of the distribution of the time to complete S phase given the initial distribution. Using the Markov approach we also made an estimate of the mean number of active replicons during S phase.ConclusionsA Markov pure birth process has shown to be useful to model the progression of cells through S phase and to increase knowledge about the variability in the length of S phase and a large variation is shown. © 2005 Wiley‐Liss, Inc.
Detection and quantification of circulating tumor cells in mouse models of human breast cancer using immunomagnetic enrichment and multiparameter flow cytometry
Authors: Allan Alison L. , Vantyghem Sharon A. , Tuck Alan B. , Chambers Ann F. , Chin‐Yee Ian H. , Keeney Michael 
Published: April 2005

AbstractBackgroundCirculating tumor cells (CTCs) in the peripheral blood of breast cancer patients may be an important indicator of metastatic disease and poor prognosis. However, the use of experimental models is required to fully elucidate the functional consequences of CTCs. The purpose of this study was to optimize the sensitivity of multiparameter flow cytometry for detection of human tumor cells in mouse models of breast cancer.MethodsMDA‐MB‐468 human breast cancer cells were serially diluted in whole mouse blood. Samples were lysed and incubated with a fluorescein isothiocyanate–conjugated anti–human leukocytic antigen antibody and a phycoerythrin‐conjugated anti‐mouse pan‐leukocyte CD45 antibody. Samples were then immunomagnetically depleted of CD45‐positive leukocytes, fixed, permeabilized, and stained with propidium iodide before flow cytometric analysis.ResultsHuman breast cancer cells could be differentiated from mouse leukocytes based on increased light scatter, cell surface marker expression, and aneuploid DNA content. The method was found to have a lower sensitivity limit of 10−5 and was effective for detecting human breast cancer cells in vivo in the circulation of experimental mice carrying primary human mammary tumors.ConclusionsThis technique has the potential to be a valuable and sensitive tool for investigating the biological relevance of CTCs in experimental mouse models of breast cancer. © 2005 Wiley‐Liss, Inc.
The human β‐glucan receptor is widely expressed and functionally equivalent to murine Dectin‐1 on primary cells
Authors: Willment Janet A. , Marshall Andrew S. J. , Reid Delyth M. , Williams David L. , Wong Simon Y. C. , Gordon Siamon , Brown Gordon D. 
Published: April 2005

AbstractWe identified the C‐type‐lectin‐like receptor, Dectin‐1, as the major receptor for fungal β‐glucans on murine macrophages and have demonstrated that it plays a significant role in the cellular response to these carbohydrates. Using two novel, isoform‐specific mAb, we show here that human Dectin‐1, the β‐glucan receptor (βGR), is widely expressed and present on all monocyte populations as well as macrophages, DC, neutrophils and eosinophils. This receptor is also expressed on B cells and a subpopulation of T cells, demonstrating that human Dectin‐1 is not myeloid restricted. Both major functional βGR isoforms – βGR‐A and βGR‐B – were expressed by these cell populations in peripheral blood; however, only βGR‐B was significantly expressed on mature monocyte‐derived macrophages and immature DC, suggesting cell‐specific control of isoform expression. Inflammatory cells, recruited in vivo using a new skin‐window technique, demonstrated that Dectin‐1 expression was not significantly modulated on macrophages during inflammation, but is decreased on recruited granulocytes. Despite previous reports detailing the involvement of other β‐glucan receptors on mature human macrophages, we have demonstrated that Dectin‐1 acted as the major β‐glucan receptor on these cells and contributed to the inflammatory response to these carbohydrates.
Nitrosyl Ruthenium Diolato Complexes
Authors: Barth Michael , Kästele Xaver , Klüfers Peter 
Published: April 2005

Abstract[mer‐(dien)(NO)Ru(AnErytH–2)]BPh4·2 H2O (1), [mer‐(dien)(NO)Ru(R,R‐ChxdH–2)]BPh4 (2), [mer‐(dien)(NO)Ru(EthdH–2)]BPh4 (3), and [mer‐(dien)(NO)Ru(Me‐β‐D‐Ribf2,3H–2)]BPh4·5.5 H2O (4) have been synthesized in the form of light pink crystals by the reaction of [mer‐(dien)(NO)RuCl2]X with the respective diol in aqueous sodium hydroxide solution (dien = diethylenetriamine, AnEryt = anhydroerythritol, Chxd = cyclohexane‐1,2‐diol, Ethd = ethanediol, Rib = ribose; X = BPh4 or PF6). The nitrosyl ligand exhibits a strong trans influence which causes the trans‐bonded oxygen atom of the diolato ligand to form a shorter bond with the Ru centre. Mean values are 2.038 for cis and 1.946 Å for trans O‐binding. Back donation is strongly supported by the diolato ligand resulting in low energies for the N–O stretch which can be observed as low as 1805 cm–1. trans‐Oxygen atoms do not act as hydrogen‐bond acceptors in any of the cases. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium Fragments: Synthesis, Solid‐State Structure and Solution Behaviour
Authors: Barbaro Pierluigi , Di Vaira Massimo , Peruzzini Maurizio , Seniori Costantini Stefano , Stoppioni Piero 
Published: April 2005

AbstractTreatment of the cyclo‐P3 complexes [(triphos)M(η3‐P3)]‐[triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane; M = Co (1), Rh (2)] with stoichiometric amounts of [CpRu‐(CH3CN)2(PR3)]PF6 [R = Ph (3), Me (4), Cy (5)] in CH2Cl2 in the presence of CH3CN yields the bimetallic adducts [{(triphos)M}(μ,η3:1‐P3){CpRu(CH3CN)(PR3)}]PF6 [M = Co; R = Ph (6), Me (7), Cy (8); M = Rh; R = Ph, (9), Me (10), Cy (11)]. The rhodium derivatives 9 and 11, upon treatment with one equivalent of PMe3, form the complexes [{(triphos)Rh}(μ,η3:1‐P3){CpRu(PMe3)(PR3}]PF6 [R = Ph (12), Cy (13)]. On standing in CH2Cl2, the rhodium complexes 9 and 10 lose acetonitrile to yield compounds with the formula [{(triphos)Rh}(μ,η3:1,1'‐P3){CpRu(PR3)}]PF6 [R = Ph (14), Me (15)]. All the compounds have been characterised by elemental analyses and, in solution, by 31P and 1H NMR spectroscopy. The 31P{1H} EXSY NMR spectroscopic data at different temperatures of 11 and 14 have highlighted the occurrence of independent dynamic processes that exchange both the triphos and the cyclo‐P3 phosphorus nuclei. An X‐ray structural investigation carried out on 6 has confirmed the occurrence of the μ,η3:1‐ligating behaviour of the cyclo‐P3 ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Relationship between the Molecular Structure and the π–π* Transition Energy of a Lattice‐Framework Disilene: A DFT Study
Authors: Tanaka Hiromasa , Kwon Eunsang , Tsutsui Shinobu , Matsumoto Shigeki , Sakamoto Kenkichi 
Published: April 2005

AbstractThe origin of a significantly red‐shifted π–π* transitionobserved in a unique lattice‐framework disilene,2,3,4,6,7,8,2',3',4',6',7',8'‐dodeca‐tert‐butyl[5,5']bi{1,5‐di‐silatricyclo[4.2.0.01,4]octylidene}‐2,7,2',7'‐tetraene, has been elucidated by time‐dependent density functional calculations and MO energy calculations. An intramolecular through‐space interaction between the π*Si=Si orbital and the π*C=C orbitals in the lattice framework strongly stabilizes the LUMO, resulting in a small HOMO–LUMO energy gap. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
New Tris(thioimidazolyl)borate Ligands and Some Zinc Complexes Thereof
Authors: Ibrahim Mohamed M. , Shu Mouhai , Vahrenkamp Heinrich 
Published: April 2005

AbstractIn order to improve the encapsulation of metal ions coordinated by tris(thioimidazolyl)borate ligands, four new such ligands with o‐substituted phenyl substituents were synthesised as well as ones with p‐tolyl and cyclohexyl substituents. In order to provide a basis for their bioinorganic zinc complex chemistry, they were converted to some zinc‐halide, ‐carboxylate, ‐nitrate, ‐phenolate and ‐benzylate complexes. They form zinc‐perchlorate complexes which are productive starting materials for the attachment of alcohols and alkoxides at zinc, thereby yielding new structural models for the zinc enzyme alcohol dehydrogenase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Screening by NMR: A New Approach for the Study of Bioactive Natural Products? The Example of Pleurotus ostreatus Hot Water Extract
Authors: Politi Matteo , Chávez María Isabel , Cañada F. Javier , Jiménez‐Barbero Jesús 
Published: April 2005

AbstractDirect NMR screening of natural products obtained from hot water extracts of medicinal species is accomplished through STD and tr‐NOESY experiments on a crude mixture and a given protein receptor. It is shown, with use of a mushroom extract as model case, that this protocol may provide a fast and simple method, particularly useful in natural products chemistry, through which to detect the presence of ligands for a target receptor. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Donor–Acceptor‐Substituted Phenylacetylene Macrocycles with Threefold Symmetry
Authors: Traber Boris , Oeser Thomas , Gleiter Rolf 
Published: April 2005

AbstractA stepwise synthesis of the donor–acceptor‐substituted macrocycle 5,21,37‐tris(diethylamino)‐13,29,45‐trinitro[2.2.2.2.2.2]metacyclophane‐1,9,17,25,33,42‐hexayne (1a) from 3,5‐bis(3‐iodo‐5‐nitrophenylethynyl)‐N,N‐diethylaniline (11) and 3,5‐bis([3‐diethylamino‐5‐ethynylphenyl]ethynyl)nitrobenzene (12) failed, mostly due to the low solubility of 1a. The synthesis of the 5,21,37‐tris(N,N‐di‐n‐hexylamino) congener of 1a, 1b, was achieved in a one‐pot reaction from 1,3‐diiodo‐5‐nitrobenzene (3) and 3,5‐diethynyl‐N,N‐di(n‐hexyl)aniline (16) in 23 % yield. X‐ray investigations on 1b revealed a planar π ring system with an inner diameter of 10 Å. Despite a high absorbance of 1b at 300 nm, no measurable NLO activity was found. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Free‐Radical Approach to 4‐Substituted Dipicolinates
Authors: Shelkov Rimma , Melman Artem 
Published: April 2005

AbstractDimethyl pyridine‐2,6‐dicarboxylate was selectively substituted through free‐radical reactions. The substitution involves the generation of free radicals through Fenton‐type reactions, followed by hydrogen abstraction from aldehydes or alcohols. The resultant carbon‐centered acyl, alkyl, or hydroxyalkyl free radicals regioselectively attack protonated dimethyl pyridine‐2,6‐dicarboxylate at position 4, yielding the corresponding dimethyl 4‐acyl‐, 4‐alkyl‐, and 4‐(hydroxyalkyl)pyridine‐2,6‐dicarboxylates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
First Model Reactions towards the Synthesis of Sarain A Core Skeleton Based upon a Biogenetic Scenario
Authors: Hourcade Stéphane , Ferdenzi Antoine , Retailleau Pascal , Mons Stéphane , Marazano Christian 
Published: April 2005

AbstractSarain A is a complex macrocyclic marine alkaloid extracted from sponges of the order Haplosclerida. It is likely that this alkaloid shares a common origin with manzamine alkaloids, also extracted from sponges of the same order. In this paper, new concepts concerning this origin are presented and constitute the basis for a synthetic strategy. A preliminary evaluation of this strategy is presented and leads, as a first result, to a five‐step access to the bicyclic intermediate 43. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Diastereoselective Alkylation of (Arene)tricarbonylchromium and Ferrocene Complexes Using a Chiral, C2‐Symmetrical 1,2‐Diamine as Auxiliary
Authors: Alexakis Alexandre , Tomassini Axel , Andrey Olivier , Bernardinelli Gerald 
Published: April 2005

AbstractThe aminal of (benzaldehyde)tricarbonylchromium and en‐antiopure bipyrrolidine undergoes diastereoselective ortho‐metallation with butyllithium. Quenching with various electrophiles, followed by hydrolysis of the aminal, affords ortho‐substituted (benzaldehyde)tricarbonylchromium compounds with high ee (91–99 %). When quenched with Ph2PCl, a new chiral P,N‐bidentate ligand is obtained, which shows efficiency in Pd‐ and Cu‐catalysed reactions. The aminal of ferrocenecarbaldehyde could also be formed, but the ortho‐deprotonation occurs with only moderate diastereoselectivity (70 %). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis and Characterization of Phosphorus Dendrimers Containing Long, Conjugated Branches
Authors: Magro Germinal , Marchand Patrice , Sebastián Rosa‐María , Guyard‐Duhayon Carine , Caminade Anne‐Marie , Majoral Jean‐Pierre 
Published: April 2005

AbstractThe synthesis of a new family of phosphorus dendrimers is described up to the fifth generation (96 end‐groups). The reaction is based on the nucleophilic substitution of P(S)Cl2 end‐groups by 4‐hydroxy‐3‐methoxycinnamaldehyde, and by the condensation of CHO end‐groups with a dichlorophosphorhydrazide. The structure of the first generation has been determined by X‐ray diffraction. This structure shows that the OC6H3CH=CHCH=NNMeP(S) linkage is close to planarity, which indicates an extended conjugation of this linkage that leads to a semi‐rigid skeleton for these dendrimers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Improved Synthesis and Conformational Analysis of anA,D‐1,10‐Phenanthroline‐Bridged Calix[6]arene
Authors: W. Eggert Jan P. , Harrowfield Jack , Lüning Ulrich , Skelton Brian W. , White Allan H. , Löffler Frank , Konrad Serge 
Published: April 2005

AbstractThe synthesis of the A,D‐1,10‐phenanthroline‐bridged calix[6]arene 3 is improved by applying a new strategy for the synthesis of the important intermediate 2,9‐bis(bromomethyl)‐1,10‐phenanthroline (2) and variation of the bridging conditions. Crystals were obtained from two different solvent systems. Two structures were determined by X‐ray studies. Both analyses reveal a rare conformation for A,D‐bridged calix[6]arenes (uduuuu). Calculations with different methods were performed for this and other relevant conformers, and revealed various local minima. The uduuuu conformation also explains the molecular asymmetry evident in low‐temperature NMR spectra of metal complexes of 3. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Steric Effects in Enantioselective Allylic Alkylation Catalysed by Cationic(η3‐Allyl)palladium Complexes Bearing Chiral Pyridine‐Aziridine Ligands
Authors: Ferioli Federico , Fiorelli Claudio , Martelli Gianluca , Monari Magda , Savoia Diego , Tobaldin Paolo 
Published: April 2005

AbstractEnantiopure N,N′‐bidentate ligands (N,N′)*, containing substituted aziridine and aza‐aromatic rings, were prepared from imines derived from (S)‐valinol or (R)‐phenylglycinol and heteroaromatic aldehydes (2‐pyridine‐, 6‐benzyl‐2‐pyridine‐, 2‐ and 8‐quinolinecarbaldehyde) by the addition of iPrMgCl and subsequent cyclisation of the 1,2‐amino alcohol moiety to aziridine. Crystalline [(N,N′)*(η3‐allyl)Pd][SbF6] complexes were prepared from these ligands and used as catalysts in the alkylation of sodium dimethyl malonate with 1,3‐diphenyl‐2‐propenyl acetate and carbonate. By comparing the performances of two complexes bearing similar pyridine‐aziridine ligands but with a different C2‐aziridine substituent (Ph vs. iPr), a better enantioselectivity was provided by the Ph‐substituted ligand (90 % vs. 41 % ee), whereas the presence of a C6‐pyridine benzyl substituent caused inversion of the enantioselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A One‐Pot Synthesis of Doubly Unsaturated Trifluoromethyl Amines:Easy Access to CF3‐Substituted Piperidines
Authors: Magueur Guillaume , Legros Julien , Meyer Franck , Ourévitch Michèle , Crousse Benoit , Bonnet‐Delpon Danièle 
Published: April 2005

AbstractA straightforward route to trifluoromethyl analogs of piperidines is described. These syntheses involve a Barbier‐type allylation reaction of trifluoroacetaldimines, followed by N‐allylation (one‐pot), and ring‐closing metathesis. An efficient asymmetric version is also reported (>98 % de). Functionalized heterobicyclic compounds can also be obtained by a Pauson–Khand reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Chemoenzymatic, Enantioconvergent, Asymmetric Total Synthesis of(R)‐Fridamycin E
Authors: Ueberbacher Bernhard J. , Osprian Ingrid , Mayer Sandra F. , Faber Kurt 
Published: April 2005

AbstractA chemoenzymatic, asymmetric total synthesis of the anti‐biotic (R)‐fridamycin E has been accomplished following a biocatalytic deracemization procotol. The key step comprises the construction of the chiral side‐chain from a functionalized rac‐2,2‐disubstituted oxirane via a kinetic resolution/stereoinversion sequence without formation of the undesiredstereoisomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Conformational Studies on Oligosubstituted Adamantane Derivatives – Structural Features of Tetravinyl‐, Tetracyclopropyl‐, and Tetraisopropyladamantane
Authors: Kozhushkov Sergei I. , Yufit Dmitry S. , Boese Roland , Bläser Dieter , Schreiner Peter R. , de Meijere Armin 
Published: April 2005

Abstract1,3‐Diisopropyl‐ (4), 1‐tert‐butyl‐3‐isopropyl‐ (5), 1,3,5‐triisopropyl‐ (6) and 1‐tert‐butyl‐3,5‐diisopropyladamantane (7) were prepared from the same synthetic precursor – methyl 3‐isopropyladamantane‐1‐carboxylate (10) – applying a standard set of repetitive procedures in 65, 77, 24, and 34 % overall yield, respectively. 1,3,5,7‐Tetraethenyladamantane (17) was obtained in two steps – Swern oxidation and Wittig olefination – from 1,3,5,7‐tetrakis(hydroxymethyl)adamantane (15) in 45 % overall yield and converted into 1,3,5,7‐tetracyclopropyladamantane (8) by fourfold cyclopropanation with diazomethane catalyzed by palladium(II) acetate (91 % yield). Hydrogenolysis of 8 over a platinum catalyst furnished 1,3,5,7‐tetraisopropyladamantane (9) in quantitative yield. 1‐Isopropyladamantane (3) as well as the hydrocarbons 4–7 did not give any crystals suitable for X‐ray crystal structure analysis, even when using the Optical Heating and Crystallization Device (OHCD). This method was rather successful when applied to the tetravinyl derivative 17, X‐ray crystal structure analysis of which revealed an approximately C2‐symmetric conformation in the solid state at 150 K. However, no well‐defined orientation was detected for the cyclopropyl groups in 8, and the molecules were severely disordered even at 30(1) K. In contrast to this, X‐ray crystal structure analysis of the tetraisopropyl derivative 9 revealed an S4‐symmetric conformation for this hydrocarbon at 203 K. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Heck Reaction of Protected Allyl Alcohols with Aryl Bromides Catalyzed by a Tetraphosphanepalladium Complex
Authors: Berthiol Florian , Doucet Henri , Santelli Maurice 
Published: April 2005

AbstractA range of aryl bromides undergo a Heck vinylation reaction with a protected allyl alcohol in the presence of[PdCl(C3H5)]2/cis,cis,cis‐1,2,3,4‐tetrakis(diphenylphosphan‐ylmethyl)cyclopentane as a catalyst. The reactivity of these allyl alcohol derivatives using a variety of protecting groups has been studied. The best results in terms of substrate/catalyst ratio were obtained with a THP protecting group. In most cases, the major isomer obtained was the (E)‐cinnamyl alcohol derivative. The reaction tolerates several functionalities, such as trifluoromethyl, methoxy, dimethylamino, acetyl, formyl or nitrile. Furthermore, this catalyst can be used at low loadings, even for reactions with sterically hindered substrates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis and Absolute Configuration of Hyperaspine, an Alkaloid of the Ladybird Hyperaspis campestris
Authors: Dooms Cédric , Laurent Pascal , Daloze Désiré , Pasteels Jacques , Nedved Oldrich , Braekman Jean‐Claude 
Published: April 2005

AbstractHyperaspine (1a), isolated from the European Coccinellidae Hyperaspis campestris, isthe first representative of a new type of ladybird alkaloids having a 3‐oxaquinolizidine skeleton. A new total synthesis of (±)‐hyperaspine starting from protected piperidin‐4‐one has been achieved. The absolute configuration of the natural alkaloid was unequivocally established to be 3S,4aS,6R,8S by HPLC analyses on a chiral column. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Pauson–Khand Approach to New Carbocyclic Nucleoside Analogs
Authors: Lanver Andreas , Schmalz Hans‐Günther 
Published: April 2005

AbstractThe synthesis of three new carbocyclic nucleoside analogs (CNAs) with the nucleobase attached to a 3′‐hydroxymethylcyclopent‐2′‐en‐1′‐yl scaffold is reported. A variety of symmetric dienynes (propargylic acetals of type 11) were used as substrates in a cobalt‐mediated Pauson–Khand (PK) reaction to give bicyclic cyclopentenone derivatives of type rac‐12 with high diastereoselectivity. These compounds are valuable building blocks for the synthesis of structurally diverse CNAs with a high biological potential as apoptosis‐inducing agents. Starting from the PK product rac‐12a, the synthesis of 4′‐trialkylsilyloxyethyl‐substituted nucleosides rac‐18 and rac‐19 (with 5‐bromouracil and 6‐chloropurine as a nucleo‐base, respectively) was accomplished in seven steps (28 % and 37 % overall yield). The regio‐ and diastereoselective nucleobase (NB) introduction was achieved by Pd0‐catalyzed allylic substitution. Starting from the PK product rac‐12e, the 2′‐phenyl‐4′‐trialkylsilyloxymethyl‐substituted CNA rac‐17 was prepared (6 steps, 29 % yield)by exploitingan alternative protocol — a Mitsunobu reaction — for the NB introduction. The key intermediates 12a and 12e were obtained in virtually enantiopure form by kinetic resolution by means of oxazaborolidine‐catalyzed borane reduction (CBS reduction) in the presence of a (R)‐diphenylprolinol‐derived B‐methyl oxazaborolidine catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The RuO4‐Catalyzed Ketohydroxylation, Part II:A Regio‐, Chemo‐ and Stereoselectivity Study
Authors: Plietker Bernd 
Published: April 2005

AbstractThe direct RuO4‐catalyzed ketohydroxylation of olefins is a new and convenient method for the preparation of a wide range of symmetrical and unsymmetrical α‐hydroxy ketones. Since reactions in which two different functional groups are introduced in one step always involve regio‐, chemo‐ and stereoselectivity issues, this paper gives a full account of investigations of various selectivity aspects in the ketohydroxylation. Stereoselectivity issues were examined in the final part of the present report. The Kishi rules, known from OsO4‐catalyzed dihydroxylations, are found to be valid for the RuO4‐catalyzed ketohydroxylation and lead to moderate to good diastereomeric ratios in the oxidation of olefins possessing an allylic center of chirality. Furthermore, competition experiments between different substituted olefins led to a reactivity profile applicable to the prediction of which is the most reactive of different C=C double bonds present in a molecule. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)