Abstract Ausgehend von der Glucopyranose (I) werden durch Umsetzung mit Acylchloriden (II) die Diacylderivate (III) dargestellt (in trennbaren Gemischen mit dem entsprechenden α‐Anomeren), aus denen mit HBr die α‐D‐Glucosylbromide (IVa) erhalten werden.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHydrogen-bonded liquid crystals. Novel mesogens incorporating nonmesogenic bipyridyl compounds through complexation between hydrogen-bond donor and acceptor moietiesTakashi Kato, Jean M. J. Frechet, Paul G. Wilson, Takeshi Saito, Toshiyuki Uryu, Akira Fujishima, Chihiro Jin, and Fumiko KaneuchiCite this: Chem. Mater. 1993, 5, 8, 1094–1100Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published inissue 1 August 1993https://pubs.acs.org/doi/10.1021/cm00032a012https://doi.org/10.1021/cm00032a012research-articleACS PublicationsRequest reuse permissionsArticle Views1441Altmetric-Citations253LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Acetolysis of 1,6-anhydro-2,3,4-tri-O-benzyl-β-D-galactopyranose (3) followed by de-O-acetylation and p-nitrobenzoylation gave 2,3,4-tri-O-benzyl-1,6-di-O-p-nitrobenzoyl-β-D-galactopyranose (4) which was converted into 2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-D-galactopyranosyl bromide (5). Benzylation of methyl 4,6-O-benzylidene-α-D-galactopyranoside (6) gave the 2,3-dibenzyl ether (7) which was hydrolyzed to 2,3-di-O-benzyl-D-galactose (8). p-Nitrobenzoylation of 8 furnished 2,3-di-O-benzyl-1,5,6-tri-O-p-nitrobenzoyl-β-D-galactofuranose (9) and an isomer, presumably a β-pyranose derivative (10). Compound 9 was converted into 2,3-di-O-benzyl-5,6-di-O-p;-nitrobenzoyl-β-D-galactofuranosyl bromide (11) and chloride (12). The new halides 5, 11, and 12 as well as known 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl bromide (1) and chloride (2) were subjected to methanolysis in dichloromethane solution in the presence of methanol alone and in the presence of tetrabutylammonium bromide, mercuric cyanide, and silver tetrafluoroborate, respectively, and the ratios of anomeric glycosides produced were examined by n.m.r. spectroscopy. Factors influencing stereoselectivity in these reactions are discussed. The new methyl α- and β-glycosides derived from 5 (13 and 14) and the methyl α-glycoside (15) produced from 11 and 12 were isolated, and methyl 2,3,5,6-tetra-O-benzyl-α-D-galactofuranoside (16) was prepared for the first time.

The search for advanced resists that can provide the high density of circuits and high throughput required for the new generations of microelectronic devices requires that highly stable chemically amplified materials be developed. In view of the high susceptibility of resists based on photoacid generation to environmental contamination, resulting in lessened performance, a program aiming at the development of chemically amplified resists utilizing photobase generation has been undertaken. In a first approach, the photogenerated amines we developed in the first stage of this project were used as catalysts for the decarboxylation of totally new resist systems containing active carboxylic acid pendant groups. The resists materials could be developed to afford negative tone images through wet development in aqueous base, or positive tone images through dry development using a gas-phase silylation reaction followed by oxygen plasma etching. The first patterning experiments carried out with two new resists utilizing photogenerated base have confirmed the validity of the approach.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTLight-Driven Catalysis within Dendrimers: Designing Amphiphilic Singlet Oxygen SensitizersStefan Hecht and Jean M. J. FréchetView Author Information Department of Chemistry, University of California Berkeley, California 94720-1460 Cite this: J. Am. Chem. Soc. 2001, 123, 28, 6959–6960Publication Date (Web):June 20, 2001Publication History Received24 April 2001Published online20 June 2001Published inissue 1 July 2001https://pubs.acs.org/doi/10.1021/ja016076shttps://doi.org/10.1021/ja016076srapid-communicationACS PublicationsCopyright © 2001 American Chemical SocietyRequest reuse permissionsArticle Views1383Altmetric-Citations100LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Catalysts,Dendrons,Hydrocarbons,Hydrophobicity,Redox reactions Get e-Alerts

Near-field scanning optical microscopy (NSOM) has been used to investigate the photophysical characteristics of first- to fourth-generation (G1 to G4) light-harvesting dendrimer thin films containing coumarin-343 and coumarin-2 as the core and peripheral chromophores, respectively. Thin film photoluminescence (PL) spectra exhibit a significant red shift in the lower generations (G1, G2, and G3) as compared to their respective solution PL spectra, implying the formation of excimers. Spatially resolved PL NSOM images exhibit pronounced nanoscopic domains in G1, which become more homogeneous in higher generations due to site-isolation of the core chromophore. G4 exhibits complete site-isolation for these light-harvesting dendrimer films.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDivergent Synthesis of Dendronized Poly(p-hydroxystyrene)Scott M. Grayson and Jean M. J. FréchetView Author Information Center for New Directions in Organic Synthesis,† Department of Chemistry, University of California, Berkeley, California 94720-1460, and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 Cite this: Macromolecules 2001, 34, 19, 6542–6544Publication Date (Web):August 11, 2001Publication History Received23 April 2001Published online11 August 2001Published inissue 1 September 2001https://pubs.acs.org/doi/10.1021/ma010698ghttps://doi.org/10.1021/ma010698grapid-communicationACS PublicationsCopyright © 2001 American Chemical SocietyRequest reuse permissionsArticle Views880Altmetric-Citations102LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Dendrons,Materials,Organic reactions,Physical and chemical properties,Polymers Get e-Alerts

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

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymeric Reagents. Preparation of Resins Containing Polyvinylperbenzoic Acid UnitsJean M. J. Fréchet and Kazi E. HaqueCite this: Macromolecules 1975, 8, 2, 130–134Publication Date (Print):March 1, 1975Publication History Published online1 May 2002Published inissue 1 March 1975https://pubs.acs.org/doi/10.1021/ma60044a008https://doi.org/10.1021/ma60044a008research-articleACS PublicationsRequest reuse permissionsArticle Views182Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Abstract The stability of a hydrogen-bonded complex built through inter-molecular hydrogen bonding between carboxylic acid and pyridine fragments has been examined using infrared spectroscopy. Infrared spectra as a function of temperature have been recorded for the 1:1 complex of 4-hexyloxybenzoic acid and trans-4-propoxy-4′-stilbazole from the crystalline state to the isotropic state. A dependence of the stability of the hydrogen bond on molecular orientation is observed clearly in the infrared spectra. The spectra also suggest that the hydrogen bond is an unionized type with a double minimum potential energy.

Capillaries with inner diameters of 550 microm have successfully been packed with 1.5-microm octadecyl silica particles using frits made of macroporous polymers by the UV photopolymerization of a solution of glycidyl methacrylate and trimethylolpropane trimethacrylate. This type of frit is found superior to one made of low-melting point poly(styrene-co-divinylbenzene) beads. Bubble formation is not observed to occur within these capillary columns under our experimental conditions. Separations can be achieved with sample injection volumes as high as 1 microL. To demonstrate its semipreparative use, a mixture of 500 nL of taxol (20 mM) and its precursor, baccatin III (30 mM), is separated using such a column with a Tris buffer.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdditions and Corrections - Chemical Synthesis and Structure Proof of a Stereoregular Linear Mannan, Poly-α-(1→6')-anhydro-D-mannopyranose Jean Frechet and Conrad SchuerchCite this: J. Am. Chem. Soc. 1969, 91, 20, 5697Publication Date (Print):September 1, 1969Publication History Published online26 April 2004Published inissue 1 September 1969https://pubs.acs.org/doi/10.1021/ja01048a606https://doi.org/10.1021/ja01048a606research-articleACS PublicationsRequest reuse permissionsArticle Views33Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolid-phase synthesis of oligosaccharides. I. Preparation of the solid support. Poly[p-(1-propen-3-ol-1-yl)styrene]Conrad Schuerch and Jean M. FrechetCite this: J. Am. Chem. Soc. 1971, 93, 2, 492–496Publication Date (Print):January 1, 1971Publication History Published online1 May 2002Published inissue 1 January 1971https://pubs.acs.org/doi/10.1021/ja00731a031https://doi.org/10.1021/ja00731a031research-articleACS PublicationsRequest reuse permissionsArticle Views1278Altmetric-Citations253LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

A variety of substituted triphenylamine derivatives were prepared in nearly quantitative yields by the use of 18-crown-6 as a phase transfer catalyst under the Ullmann reaction conditions.

Abstract Novel separation media for the direct injection of complex samples have been prepared from porous 10 μrn uniformly sized poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads. The simple hydrolysis of all epoxide groups produces beads with separation characteristics similar to those of some restricted access media. The use of a novel size-specific modification of porous materials provides separation media with even better chromatographic properties. In this approach, hydrolysis of the epoxide groups to diols can be carried out exclusively within the large pores of the medium through the use of a polymeric catalyst. The epoxide groups remaining in the small pores after hydrophilization of the large pores were then transformed either to hydrophobic C18 or phenyl groups, or to more polar diethylamino groups. Due to the size specific characteristics of the modification process used in the preparation of the beads which renders the large pores hydrophilic, no protein interaction with the surface of the pores was observed, the protein recovery was high, and the retention times of proteins and of a non-retained probe was similar. Examples of separations of drugs from plasma document the good efficiency and excellent selectivity of columns packed with the novel separation medium.