1,720,969 research outputs found
Synthesis of enantiomerically pure (S)-1,2-epoxy-4-methylpentane starting from D-mannitol
No full textThe title compd. (I) was prepd. from D-mannitol by isopropylidenation, Pb(OAc)4 oxidn., redn., Grignard reaction with Me2CHCl, and bromination-dehydrobromination of II. Grignard reaction of I with CH2:CHCCl:CH2 gave (S)-ipsenol
Regio- and stereospecific syntheses of achiral terpenoid allomones and pheromone components: dendrolasin, (E)-beta-farnesene, and beta-springene
No full textChem. and stereoisomerically pure dendrolasin [I, R = (E)-Q] (Q = Me2C:CHCH2CH2CMe:CHCH2) was prepd. by Grignard reaction of I (R = Br) with (E)-QOHc in the presence of Li2CuCl4, whereas similar reaction of neryl acetate gave 99% stereoisomerically pure I (R = neryl). Moreover, β-farnesene [(E)-QCH2C(:CH2)CH:CH2) and β-springene [(E,E)-CH2:CHC(:CH2)CH2CH2CH:CMeCH2CH2CH:CMeCH2CH2CH:CMe2] were prepd. via coupling of the π-allylnickel halide complex derived from Me2C:CHCH2Br with BrCH2CMe:CHCH2CH2C(:CH2)CH:CH2 (II) or similar reaction of the π-allylnickel complex derived from II with QBr, resp
Toward the synthesis of immunogenic glycodendrimers based on 2-acetamidohexopyranose containing disaccharides
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Synthesis of beta-D-ManNAc containing di- and trisaccharide building-blocks for the preparation of immunogenic glycodedrimers
No full textStereoselective synthesis of a model alfa-glycoside of the beta-D-ManNAcp-(1-->4)-D-Glc disaccharide starting from lactose, avoiding the beta-mannosaminylation step
No full textA model isopropyl a-glycoside of the beta-D-ManNAc-(1→4)-D-Glc disaccharide has been prepared from
lactose, avoiding the b-mannosaminylation step. Three complementary approaches involving first the preparation and then the glycosidation of beta-thiophenyl donors of the protected disaccharides, (a) beta-DManNAc-(1→4)-D-Glc, (b) beta-D-TalNAc-(1→4)-D-Glc and (c) lactose, were compared. The best results were obtained employing a suitably protected lactose donor, and submitting its a-isopropyl glycoside to an amination with inversion in position 2’ followed by an epimerization at C-4’
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