Structure of the D-glucans produced by Neisseria perflava

1978 ◽  
Vol 24 (11) ◽  
pp. 1419-1422 ◽  
Author(s):  
C. R. MacKenzie ◽  
M. B. Perry ◽  
I. J. McDonald ◽  
K. G. Johnson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Optical Rotation ◽  
Side Chains ◽  
Cell Free Extract ◽  
Branch Points ◽  
Methylation Analysis ◽  
A Cell ◽  
Neisseria Perflava ◽  
Nuclear Magnetic

A chemical and enzymic study of the cellular glucan of Neisseria perflava and of the glucan produced from sucrose by a cell-free extract of N. perflava showed from optical rotation, 13C nuclear magnetic resonance, methylation analysis, and α- and β-amylase hydrolysis studies that the glucans had glycogen-like structures. These structures were composed of chains of 1-4-α-D-glucopyranosyl units with branch points of 4-O- and 6-O- disubstituted D-glucopyranose units. While the backbone structures of the two glucans were similar, the release of maltose by the action of β-amylase indicated that the 1–4 linked nonreducing side chains of the cell-free enzymically synthesized glucan were longer (~seven units) than those present in the cellular glucan (~two to three units), a result in agreement with methylation analyses.

THE STRUCTURE OF RETAMINE AND THE PARTIAL SYNTHESIS OF THE (−)-ENANTIOMORPH

1965 ◽  
Vol 43 (7) ◽  
pp. 2012-2016 ◽  
Author(s):  
Kju Hi Shin ◽  
L. Fonzes ◽  
Léo Marion
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Opposite Sign ◽  
Optical Rotation ◽  
Partial Synthesis ◽  
Dehydration Product ◽  
Layer Chromatography ◽  
Nuclear Magnetic

Previous work by many authors has led to the assumption that retamine might be (+)-12-hydroxysparteine. A partial synthesis of the enantiomorph of this compound has been effected by dehydration of (+)-13-hydroxylupanine and hydroboration of the product. The dehydration product consisted of two components that were separated by thin-layer chromatography and identified by the characteristics of their nuclear magnetic resonance (n.m.r.) spectra as Δ12,13-and Δ13,14-dehydrolupanine. Hydroboration of the Δ12,13-isomer gave rise to (−)-12-hydroxy-sparteine having, in thin-layer chromatography, the same Rf value as natural retamine and the same optical rotation numerically, although of opposite sign. The synthetic base had the same infrared and n.m.r. spectra as the alkaloid and the two had superimposable Debye–Scherrer patterns. Evidence is given showing the hydroxyl to be equatorial.

Semiempirical calculation of 13C nuclear magnetic resonance chemical shifts of acyclic hydrocarbons. Application to the stereochemical analysis of steroidal side chains

1988 ◽  
Vol 66 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Manuel Gonzalez-Sierra ◽  
Daniel A. Bustos ◽  
Edmundo A. Ruveda ◽  
Alejandro C. Olivieri ◽  
Mariano Grasselli
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Side Chains ◽  
Stereochemical Analysis ◽  
Microcomputer Program ◽  
Semiempirical Approach ◽  
13C Nuclear Magnetic Resonance ◽  
Acyclic Hydrocarbons ◽  
Nuclear Magnetic

A semiempirical approach for predicting 13C nuclear magnetic resonance chemical shifts of acyclic hydrocarbons has been adapted to a microcomputer program. A series of methyl and dimethyl substituted cholesterols has been studied using this program, and the predicted shifts are in agreement with literature reports. Preferred conformations of the steroidal side chains have been also predicted and agree with previous studies. A simple rule for analyzing the trends in the chemical shift of the carbon C-20, which is sensitive to changes in the configuration at C-22, is also given, not only for hydrocarbon side chains but also for hydroxy substituted compounds.

The structure of the antigenic lipopolysaccharide O-chain produced by Escherichiahermannii ATCC 33650 and 33652

1990 ◽  
Vol 68 (8) ◽  
pp. 1456-1466 ◽  
Author(s):  
Linda M. Beynon ◽  
David R. Bundle ◽  
Malcolm B. Perry
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Molecular Modelling ◽  
Partial Hydrolysis ◽  
Two Dimensional ◽  
Methylation Analysis ◽  
Structure Formula ◽  
Structural Methods ◽  
Nuclear Magnetic

High resolution two-dimensional 1H and 13C nuclear magnetic resonance at 500 MHz was used in combination with molecular modelling to solve the structures of the antigenic O-polysaccharides produced by Escherichiahermannii strains ATCC 33650 and 33652. Classical structural methods such as methylation analysis, selective and partial hydrolysis, and periodate oxidations confirmed that the O-polysaccharides had a branched tetrasaccharide repeating unit with the structure:[Formula: see text]Keywords: Escherichiahermannii, lipopolysaccharide, magnetic resonance, polysaccharide.

FRIEDEL–CRAFTS REARRANGEMENTS: II. REARRANGEMENTS DURING CYCLIALKYLATION OF ε-ARYL-SUBSTITUTED COMPOUNDS

1964 ◽  
Vol 42 (3) ◽  
pp. 579-590 ◽  
Author(s):  
L. R. C. Barclay ◽  
B. A. Ginn ◽  
C. E. Milligan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Side Chains ◽  
Alternative Mechanism ◽  
Nuclear Magnetic

Friedel–Crafts cyclialkylation of aromatics such as 1,1,4,4-tetramethyltetralin with 2,6-dichloro-2,6-dimethylheptane does not yield a benzsuberane as previously reported. Several 5-phenyl-substituted chlorides, alcohols, and olefins were synthesized for cyclialkylation studies. These included 2-chloro-2,6-dimethyl-6-phenylheptane (Xa), 3-chloro-3,7-dimethyl-7-phenyloctane (Xb), 2,6-dimethyl-6-phenyl-2-heptanol, 2,6-dimethyl-6-phenyl-2-hepten-4-one (XX), 2-chloro-6-methyl-6-phenylheptane, and 1-chloro-5-phenylpentane (XXIV). Cyclialkylation of Xa (and the corresponding alcohol), Xb, 2-chloro-6-methyl-6-phenyl-heptane, and XXIV produced alkyltetralins instead of benzsuberanes. Evidence is presented and discussed which indicates that the alkyltetralins form by rearrangements in the side chains of the aryl-substituted systems. The alternative mechanism involving rearrangement of a benzsuberane intermediate via a phenonium ion mechanism was unequivocally ruled out in at least one case—the cyclization of Xb. Nuclear magnetic resonance evidence is presented for the structural assignments.

The structures of the two lipopolysaccharide O-chains produced by Salmonella boecker

1988 ◽  
Vol 66 (10) ◽  
pp. 1066-1077 ◽  
Author(s):  
Jean-Robert Brisson ◽  
Malcolm B. Perry
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Molecular Weight ◽  
Nitrous Acid ◽  
Optical Rotation ◽  
Partial Hydrolysis ◽  
Magnetic Resonance Studies ◽  
High Molecular Weight Polymers ◽  
Nuclear Magnetic

Salmonella boecker, which belongs to group 0:6, 14(H) and shows the antigenic factors 6, 14, [1], and [25], defined by the Kauffmann–White system, produces two lipopolysaccharides differing from each other in the structures of their 0-polysaccharide moieties. By glycose composition, partial hydrolysis, nitrous acid deamination, methylation, optical rotation, and 1H and 13C nuclear magnetic resonance studies, the O-polysaccharides were demonstrated to be high-molecular-weight polymers (I and II) composed of either structurally related repeating tetrasaccharide or repeating pentasaccharide units having the structuresand[Formula: see text][Formula: see text]

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