New Constrained Amines in a Bicyclo[2.2.1]Heptane Skeleton

2018 ◽  
Vol 69 (9) ◽  
pp. 2448-2453 ◽  
Author(s):  
Constantin I. Tanase ◽  
Constantin Draghici ◽  
Catalina Negut ◽  
Lucia Pintilie
Keyword(s):  
Click Chemistry ◽  
Selective Reduction ◽  
Optically Active ◽  
Pure Form ◽  
High Yield ◽  
Protecting Group ◽  
Efficient Procedure ◽  
Primary Hydroxyl ◽  
Selective Crystallization ◽  
Heterocyclic Bases

In this paper we present an efficient procedure for obtaining ether-protected bicyclo[2.2.1]heptane amines in six steps, from an optically active keto-alcohol norbornane compound, for building the heterocyclic bases of pyrimidine and purine constrained nucleosides. Trityl as protecting group makes it possible to isolate 5-endo-compounds in pure form by selective crystallization, and to isolate the intermediates in the next 3 steps of the reaction by crystallization. With TBDMS, all compounds were obtained as oil. The direct selective reduction of the keto-alcohol norbornane compound gave the pure 5-endo-diol 4d in high yield, which was then selectively protected at the primary hydroxyl with a trityl group; the next steps are similar for obtaining the trityl-protected bicyclo[2.2.1]heptane amine. The azide intermediates are valuable intermediates for click chemistry.

scholarly journals A mutually stabilized host-guest pair

2019 ◽  
Vol 5 (11) ◽  
pp. eaax6707 ◽  
Author(s):  
Chi Zhang ◽  
Hongye Wang ◽  
Jie Zhong ◽  
Ye Lei ◽  
Renfeng Du ◽  
...  
Keyword(s):  
Click Chemistry ◽  
Uv Light ◽  
Alder Reaction ◽  
Diels Alder ◽  
Protecting Group ◽  
Face To Face ◽  
Π Interactions ◽  
Diels Alder Reaction

By using click chemistry, a hexacationic cage was synthesized. The cage contains two triscationic π-electron–deficient trispyridiniumtriazine (TPZ3+) platforms that are bridged in a face-to-face manner by three ethylene-triazole-ethylene linkers. A diversity of π-electron–rich guests can be recognized within the pocket of the cage, driven by host-guest π-π interactions. The cage cavity acts as a protecting group, preventing an anthracene guest from undergoing Diels-Alder reaction. Under ultraviolet (UV) light, the pyridinium C─N bonds in TPZ3+ platforms are polarized and weakened, resulting in the occurrence of cage decomposition via β-elimination. Guest recognition could help to prevent this UV-stimulated cage decomposition by suppressing the excitation of the TPZ3+ units.

High-yield purification of the complex-forming glycoprotein in urine from normal and abnormal subjects.

1989 ◽  
Vol 35 (4) ◽  
pp. 577-581 ◽  
Author(s):  
H Wakui ◽  
R Kobayashi ◽  
H Itoh ◽  
H Imai ◽  
Y Nakamoto ◽  
...  
Keyword(s):  
Biochemical Properties ◽  
High Yield ◽  
Gel Chromatography ◽  
Tubular Proteinuria ◽  
Charge Heterogeneity ◽  
Purification Method ◽  
Efficient Procedure ◽  
Renal Disorders ◽  
Special Collection ◽  
Urine Specimens

Abstract Ordinary methods for purification of complex-forming glycoprotein (protein HC) or alpha 1-microglobulin, a protein closely related to protein HC, require either large volumes of urine or special collection of urine specimens from patients with tubular proteinuria. Here we describe a fast, efficient procedure for isolating protein HC in high yield from urines from healthy and diseased subjects, with use of Cibacron blue, hydroxylapatite, and gel chromatography. Using this procedure, we also obtained a considerable amount of polymeric protein HC from the urine of a patient with chronic renal failure. The pattern of charge heterogeneity and immunoreactivity with anti-protein HC differed between the polymeric and monomeric forms of protein HC. We also observed a variability in charge heterogeneity of protein HC among patients with renal disorders. These results demonstrate that this purification method is useful for further studies to elucidate the biochemical properties of protein HC and its clinical significance in renal disorders.

scholarly journals Palladium-catalyzed α-arylation for the addition of small rings to aromatic compounds

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhi-Tao He ◽  
John F. Hartwig
Keyword(s):  
Electronic Properties ◽  
Aromatic Compounds ◽  
Ring Opening ◽  
Biologically Active ◽  
High Yield ◽  
Protecting Group ◽  
Mechanistic Studies ◽  
Claisen Condensation ◽  
Wide Range ◽  
Palladium Catalyzed

Abstract Small, strained rings have rigid, defined conformations and unique electronic properties. For these reasons, many groups seek to use these subunits to form biologically active molecules. We report a generally applicable approach to attach small rings to a wide range of aromatic compounds by palladium-catalyzed α-arylation of cyclopropyl, cyclobutyl and azetidinyl esters. The direct α-arylation of cyclopropyl esters and cyclobutyl esters is achieved in high yield by ensuring that the rate of coupling exceeds the rate of Claisen condensation. The α-arylation of azetidines is achieved without ring opening of the strained saturated heterocycle by conducting the reactions with an azetidine derivative bearing a benzyl protecting group on nitrogen. Mechanistic studies show that the α-arylation of small rings is challenging because of the weak acidity of α C-H bond (cyclopropanes), strong sensitivity of the strained esters to Claisen condensation (cyclobutatanes), or facile decomposition of the enolates (azetidinyl esters).

ChemInform Abstract: A Simple, Mild, and Efficient Procedure for High-Yield Synthesis of Benzimidazoles Using Copper Triflate as Catalyst.

ChemInform ◽  
2010 ◽  
Vol 41 (24) ◽  
pp. no-no
Author(s):  
M. Adharvana Chari ◽  
P. Sadanandam ◽  
D. Shobha ◽  
K. Mukkanti
Keyword(s):  
High Yield ◽  
Efficient Procedure

scholarly journals Straightforward synthesis of a tetrasaccharide repeating unit corresponding to theO-antigen ofEscherichia coliO16

2013 ◽  
Vol 9 ◽  
pp. 1757-1762 ◽  
Author(s):  
Manas Jana ◽  
Anup Kumar Misra
Keyword(s):  
Escherichia Coli ◽  
High Yield ◽  
Protecting Group ◽  
Target Compound ◽  
One Pot ◽  
Minimum Number

A straightforward synthesis of the tetrasaccharide repeating unit of theO-antigen ofEscherichia coliO16 has been achieved following a sequential glycosylation strategy. A minimum number of steps was used for the synthesis of the target compound involving a one-pot glycosylation and a protecting group manipulation. All intermediate reactions afford their products in high yield, and the glycosylation steps are stereoselective.

Glycoconjugation of 4-Methylumbelliferone via “Click Chemistry”

2014 ◽  
Vol 881-883 ◽  
pp. 414-418
Author(s):  
Ru Chun Yang ◽  
Tao Hu ◽  
Ban Peng Cao ◽  
Xi Chen ◽  
Qiang Xiao
Keyword(s):  
Natural Products ◽  
Click Chemistry ◽  
High Yield ◽  
Dipolar Cycloaddition ◽  
Derivatives Of

A series of carbohydrate-conjugated 4-methylumbelliferone were synthesized using 1,3-dipolar cycloaddition “click chemistry” of the azide and alkyne. The reaction is straight forward and in high yield. The strategy will be useful for synthesizing glycoconjugated derivatives of natural products.

Der 2,4,6-Triisopropylbenzolsulfonyl(Tip)-Rest, eine neue Schutzgruppe für die Guanidinofunktion von Arginin / The 2,4,6-Triisopropylbenzenesulfonyl Residue, a New Protecting Group for the Guanidino Function of Arginine

1987 ◽  
Vol 42 (12) ◽  
pp. 1591-1594 ◽  
Author(s):  
Hartmut Echner ◽  
Wolfgang Voelter
Keyword(s):  
Peptide Synthesis ◽  
Sulfonyl Chloride ◽  
Trifluoromethanesulfonic Acid ◽  
High Yield ◽  
Protecting Group

AbstractThe 2.4.6-triisopropylbenzenesulfonyl group is introduced in high yield into the guanidino function of arginine by the reaction of Na-protected arginine with 2.4.6-triisopropylbenzene-sulfonyl chloride. This protecting group was found to be cleaved by commonly used reagents used in peptide synthesis like methanesulfonic, trifluoromethanesulfonic acid or mixtures of tri-fluoroacetic with methanesulfonic or trifluoromethanesulfonic acid.

A Facile and Efficient Procedure for Deprotection of 1,1-Diacetates Catalysed by H2NSO3H

2003 ◽  
Vol 2003 (1) ◽  
pp. 30-32 ◽  
Author(s):  
Tong-Shou Jin ◽  
Guang Sun, Yan–Wei Li ◽  
Tong-Shuang Li
Keyword(s):  
High Yield ◽  
Efficient Procedure

A rapid, efficient and high yield method of the deprotection of 1,1-diacetates is described which occurs under catalysis of H2NSO3H.

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