Dialkynyldiboranes(4) and the selectable reactivity of their C–H, CC and B–B bonds

2021 ◽  
Author(s):  
Fabian Schorr ◽  
Felipe Fantuzzi ◽  
Rian D. Dewhurst ◽  
Holger Braunschweig
Keyword(s):  
Selective Reactivity

The second, third and fourth examples of dialkynyldiboranes(4) are prepared and the selective reactivity of their B–B and alkynyl C–H and CC bonds is presented.

Selective reactivity of the hydroxyls of methyl quinate towards acylating agents.(1)

1969 ◽  
Vol 10 (29) ◽  
pp. 2497-2500 ◽  
Author(s):  
D. Mercier ◽  
J. Cléophax ◽  
J. Hildesheim ◽  
A.M. Sépulchre ◽  
S.D. Géro
Keyword(s):  
Selective Reactivity

scholarly journals A Genetically Encoded Picolyl Azide for Improved Live Cell Copper Click Labeling

2021 ◽  
Vol 9 ◽  
Author(s):  
Birthe Meineke ◽  
Johannes Heimgärtner ◽  
Alexander J. Craig ◽  
Michael Landreh ◽  
Lindon W. K. Moodie ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mammalian Cells ◽  
Stop Codon ◽  
Bioorthogonal Chemistry ◽  
Bioorthogonal Reaction ◽  
Noncanonical Amino Acids ◽  
Selective Reactivity ◽  
Direct Incorporation ◽  
Chelating Groups ◽  
Amber Suppression

Bioorthogonal chemistry allows rapid and highly selective reactivity in biological environments. The copper-catalyzed azide–alkyne cycloaddition (CuAAC) is a classic bioorthogonal reaction routinely used to modify azides or alkynes that have been introduced into biomolecules. Amber suppression is an efficient method for incorporating such chemical handles into proteins on the ribosome, in which noncanonical amino acids (ncAAs) are site specifically introduced into the polypeptide in response to an amber (UAG) stop codon. A variety of ncAA structures containing azides or alkynes have been proven useful for performing CuAAC chemistry on proteins. To improve CuAAC efficiency, biologically incorporated alkyne groups can be reacted with azide substrates that contain copper-chelating groups. However, the direct incorporation of copper-chelating azides into proteins has not been explored. To remedy this, we prepared the ncAA paz-lysine (PazK), which contains a picolyl azide motif. We show that PazK is efficiently incorporated into proteins by amber suppression in mammalian cells. Furthermore, PazK-labeled proteins show improved reactivity with alkyne reagents in CuAAC.

scholarly journals UNUSUAL WAY OF REACTION OF 3-AMINO-4-(5-CHLOROMETHYL-1,2,4-OXADIAZOLE-3-YL)-FURAZAN WITH HYDRAZINE

2017 ◽  
Vol 60 (4) ◽  
pp. 26
Author(s):  
Elena V. Stepanova ◽  
Andrei I. Stepanov
Keyword(s):  
Carboxylic Acid ◽  
Catalytic Amount ◽  
Acid Synthesis ◽  
Chloromethyl Group ◽  
One Pot ◽  
Isolation And Purification ◽  
Long Duration ◽  
Reaction Proceeds ◽  
Selective Reactivity ◽  
Hydrolysis Of

The results of our study of the pathways of selective reactivity of 3-amino-4-(5-chloromethyl-1,2,4-oxadiazole-3-yl)furazan versus 5-unsubstituted or 5-methyl and 5-trifluoromethyl substituted 4-(5R-1,2,4-oxadiazole-3-yl)furazans (R = H, Me, CF3) towards the action of hydrazine are discussed. If the reductive opening of 1,2,4-oxadiazole ring in unsubstituted at the С-5 atom (1,2,4-oxadiazol-3-yl)furazan derivatives under the treatment with hydrazine can be used as a method for the preparation of a range of amidrazones of 4-R-furazan-3-carboxylic acid. 3-amino-4-(5-trifluoromethyl-1,2,4-oxadiazol-3-yl)furazan with hydrazine gives amidoxime of 4-aminofurazan-3-carboxylic acid. 3-amino-4-(5-methyl-1,2,4-oxadiazol-3-yl) furazan is inert to the action of hydrazine, on the contrary the reaction of 3-amino-4-(5-chloromethyl-1,2,4-oxadiazole-3-yl)furazan with hydrazine leads to oxidation of chloromethyl group of titled compound to the carbonyl one. In this case the product of reaction of 3-amino-4-(5-chloromethyl-1,2,4-oxadiazole-3-yl)furazan with hydrazine was isolated in a form of corresponding hydrazonomethyl derivative notably as 3-amino-4-(5-hydrazonomethyl-1,2,4-oxadiazole-3-yl)furazan. A possible reaction mechanism for the formation of hydrazonomethyl group by oxidation reaction of chloromethyl group by hydrazine is proposed. 3-Amino-4-(5-hydrazonomethyl-1,2,4-oxadiazol-3-yl)furazan undergoes a transhydrazination reaction with semicarbazide and thiosemicarbazide. But our attempts to its hydrolysis for the purpose to obtain free aldehyde were unsuccessful. Thus, hydrolysis of hydrazonomethyl derivative in acetic acid in the presence of catalytic amount of sulfuric acid results in azine – N,N'-bis(3-(4-aminofurazan-3-yl)-1,2,4-oxadiazol-5-ylmethylyden)hydrazine – precipitation, long-duration boiling in hydrochloric acid leads to Kishner-Wolff reduction of the carbonyl group to 3-amino-4-(5-methyl-1,2,4-oxadiazol-3-yl)furazan, and hydrolysis in alkaline medium leads to 1,2,4-oxadiazole ring opening to amidoxime of 4-aminofurazan-3-carboxylic acid. Synthesis of 3-amino-4-(5-chloromethyl-1,2,4-oxadiazole-3-yl)furazan (R = CH2Cl) was carried out by condensation of amidoxime of 4-aminofurazan-3-carboxylic acid with an excess of chloroacetyl chloride in toluene at elevated temperature. The reaction proceeds through formation of intermediate product – 3-chloromethylamino-4-(5-chloromethyl-1,2,4-oxadiazol-3-yl)furazan. Removing of N-chloroacetyl group in such obtained intermediate was performed by hydrolysis in acidic media. One-pot synthesis without the need for isolation and purification of intermediate is allowed. The structures of obtained compounds were proved by modern methods of physical-chemical analysis (1H, 13C NMR, IR and MS spectroscopy).Forcitation:Stepanova E.V., Stepanov A.I. Unusual way of reaction of 3-amino-4-(5-chloromethyl-1,2,4-oxadiazole-3-yl)furazan with hydrazine. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 26-32.      

Selective reactivity of electron-rich aryl iodides in the Heck arylation of disubstituted alkenes catalyzed by palladium–arylurea complexes

Tetrahedron ◽  
2013 ◽  
Vol 69 (47) ◽  
pp. 10139-10151 ◽  
Author(s):  
Matthew R. Smith ◽  
Young Jin Jang ◽  
Jung Yun Kim ◽  
Marco A. Ciufolini
Keyword(s):  
Aryl Iodides ◽  
Heck Arylation ◽  
Selective Reactivity

Selective Reactivity of Myrcene for Vat Photopolymerization 3D Printing and Postfabrication Surface Modification

2019 ◽  
Vol 21 (1) ◽  
pp. 163-170 ◽  
Author(s):  
Andrew C. Weems ◽  
Kayla R. Delle Chiaie ◽  
Rachel Yee ◽  
Andrew P. Dove
Keyword(s):  
Surface Modification ◽  
3D Printing ◽  
Selective Reactivity

scholarly journals Membrane glycoconjugates expressed on sheep airway epithelium.

1994 ◽  
Vol 42 (10) ◽  
pp. 1341-1347 ◽  
Author(s):  
K Abdi ◽  
L Kobzik ◽  
X Li ◽  
S J Mentzer
Keyword(s):  
Western Blotting ◽  
Airway Epithelium ◽  
Viral Infections ◽  
Transplant Rejection ◽  
Histochemical Staining ◽  
Inflammatory Reactions ◽  
Peripheral Airways ◽  
Trichosanthes Kirilowii ◽  
Mammalian Lung ◽  
Selective Reactivity

In mammalian lung, selective airway inflammatory reactions have been associated with viral infections, transplant rejection, and autoimmune diseases. Although the molecular basis for this selective reactivity is unknown, the importance of carbohydrates in immunologic processes suggests a potential role for membrane glycoconjugates in tissue-specific inflammatory reactions. In the present work we examined a panel of 39 lectins for their pattern of reactivity in the peripheral airways of the sheep lung. The size of the panel facilitated a comprehensive description of the glycoconjugate localization on the airway epithelium. Four lectins (agglutinins for Helix aspersa, Psophocarpus tetragonolobus, Trichosanthes kirilowii, and Griffonia simplifolia II) revealed selective reactivity with the small airway epithelium. On lectin Western blotting, these four lectins demonstrated a common low molecular weight banding profile that was distinct from control lectins. The histochemical staining patterns and Western blotting profiles provided evidence for the selective expression of membrane glycoconjugates in the peripheral airways of the sheep lung.

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