Studies on polynucleotides. CXLIII. A rapid and convenient method for the synthesis of deoxyribooligonucleotides carrying 5'-phosphate end groups using a new protecting group

1976 ◽  
Vol 98 (5) ◽  
pp. 1065-1072 ◽  
Author(s):  
K. L. Agarwal ◽  
Y. A. Berlin ◽  
H. J. Fritz ◽  
M. J. Gait ◽  
D. G. Kleid ◽  
...  
Keyword(s):  
Convenient Method ◽  
Protecting Group ◽  
End Groups

Facile, Stereocontrolled Synthetic Route towards Bis-functionalised Pyrrolizidines

Synthesis ◽  
2018 ◽  
Vol 50 (21) ◽  
pp. 4295-4300
Author(s):  
Janusz Jurczak ◽  
Marcin Lindner ◽  
Antoni Krasiński
Keyword(s):  
Natural Products ◽  
Convenient Method ◽  
Reductive Cleavage ◽  
Protecting Group ◽  
Synthetic Route ◽  
Practical Application ◽  
Available N

A simple and convenient method for the synthesis of bis-functionalised pyrrolizidines starting from readily available N-Cbz-l-prolinal is described. This aldehyde was converted within two concise steps to the corresponding aminoepoxides, which were separately subjected to regioselective cyclisation induced by a reductive cleavage of the Cbz protecting group. The versatile and concise strategy holds great potential for practical application in the straightforward preparation of pyrrolizidine-based drugs and natural products.

Synthesis and Characterization of Pendant Arm Encapsulated Complexes of Cobalt(III)

1989 ◽  
Vol 42 (5) ◽  
pp. 649 ◽  
Author(s):  
AA Achilleos ◽  
LR Gahan ◽  
KA Nicolaidis
Keyword(s):  
Convenient Method ◽  
Acidic Solution ◽  
Synthesis And Characterization ◽  
Protecting Group ◽  
Chromatographic Purification ◽  
Chemical Modifications ◽  
Reaction Conditions ◽  
Pendant Arm ◽  
Derivatives Of

The synthesis and characterization of an octahedral cobalt(III) complex of the octaamine ligand 5,5-bis(4-amino-2-azabutyl)-3,7-diazanonane-1,9-diamine, [co( asen )]3+, is described. Two approaches to the preparation of encapsulated derivatives of [Co(asen)]3+ are also described. The first approach involves reaction of [Co(asen)]3+ with nitromethane and formaldehyde in the presence of base. After extensive chromatographic purification [(1-(4-amine-2-azabutyl)-8-nitro-3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane )cobalt(III)]5+ was isolated. The second more convenient method employs precautionary protection of the pendant primary amine of [Co( asen )]3+, as the benzenesulfonate, prior to reaction with the same capping reagents. Both approaches result in an encapsulated complex bearing a pendant 4-amine-2-azabutyl moiety. The protecting group is stable under reaction conditions required for successive chemical modifications of the capping nitro group to amine, chloro and proton capped cages, but is readily removed in refluxing acidic solution.

Convenient method for the analysis of primary and secondary hydroxyl end groups in polyethers

1991 ◽  
Vol 27 (2) ◽  
pp. 201-204 ◽  
Author(s):  
J. Loccufier ◽  
M. Van Bos ◽  
E. Schacht
Keyword(s):  
Convenient Method ◽  
Secondary Hydroxyl ◽  
End Groups

scholarly journals Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

2010 ◽  
Vol 6 ◽  
Author(s):  
Dhananjaya Sahoo ◽  
Susanne Thiele ◽  
Miriam Schulte ◽  
Navid Ramezanian ◽  
Adelheid Godt
Keyword(s):  
Chromatographic Separation ◽  
Side Reaction ◽  
Building Blocks ◽  
Protecting Groups ◽  
Side Chains ◽  
Protecting Group ◽  
Synthetic Route ◽  
End Groups ◽  
Pure Compounds ◽  
Better Than

One important access to monodisperse (functionalized) oligoPPEs is based on the orthogonality of the alkyne protecting groups triisopropylsilyl and hydroxymethyl (HOM) and on the polar tagging with the hydroxymethyl moiety for an easy chromatographic separation of the products. This paper provides an update of this synthetic route. For the deprotection of HOM protected alkynes, γ-MnO2 proved to be better than (highly) activated MnO2. The use of HOM as an alkyne protecting group is accompanied by carbometalation as a side reaction in the alkynyl–aryl coupling. The extent of carbometalation can be distinctly reduced through substitution of HOM for 1-hydroxyethyl. The strategy of polar tagging is extended by embedding ether linkages within the solubilising side chains. With building blocks such as 1,4-diiodo-2,5-bis(6-methoxyhexyl) less steps are needed to assemble oligoPPEs with functional end groups and the isolation of pure compounds becomes simple. For the preparation of 1,4-dialkyl-2,5-diiodobenzene a better procedure is presented together with the finding that 1,4-dialkyl-2,3-diiodobenzene, a constitutional isomer of 1,4-dialkyl-2,5-diiodobenzene, is one of the byproducts.

Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

1984 ◽  
Vol 42 ◽  
pp. 576-577
Author(s):  
M.D. Ball ◽  
H. Lagace ◽  
M.C. Thornton
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Transmission Electron Microscope ◽  
Convenient Method ◽  
Flow Chart ◽  
X Ray ◽  
Intensity Measurements ◽  
Transmission Electron ◽  
Electron Intensity ◽  
Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

Stereo imaging in the shadow electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 120-121
Author(s):  
W. C. T. Dowell
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Convenient Method ◽  
Patent Application ◽  
Standard Technique ◽  
Stereo Imaging ◽  
Stereo Images ◽  
Specimen Height

Stereo imaging is not new to electron microscopy. Von Ardenne, who first published transmission pairs nearly forty hears ago, himself refers to a patent application by Ruska in 1934. In the early days of the electron microscope von Ardenne employed a pair of magnetic lenses to view untilted specimens but soon opted for the now standard technique of tilting the specimen with respect to the beam.In the shadow electron microscope stereo images can, of course, be obtained by tilting the specimen between micrographs. This obvious method suffers from the disadvantage that the magnification is very sensitive to small changes in specimen height which accompany tilting in the less sophisticated stages and it is also time consuming. A more convenient method is provided by horizontally displacing the specimen between micrographs. The specimen is not tilted and the technique is both simple and rapid, stereo pairs being obtained in less than thirty seconds.

Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

1981 ◽  
Vol 39 ◽  
pp. 550-551
Author(s):  
Dean A. Handley ◽  
Jack T. Alexander ◽  
Shu Chien
Keyword(s):  
Cell Growth ◽  
Cell Cultures ◽  
Molecular Interactions ◽  
Convenient Method ◽  
Petri Dish ◽  
Simple Method ◽  
Thin Section Microscopy ◽  
Thin Sectioning ◽  
Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

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